NANO-TITANATE, NANO-TITANIC ACID, AND NANO-TIO2 CONTAINING DOPING AG, PREPARATION METHOD THEREFOR AND USE THEREOF

TECHNICAL FIELD

The present invention relates to the field of nanomaterials technology, and in particular relates to a nano Ag-doped titanate, a nano Ag-doped titanic acid, a nano Ag-doped TiO₂, as well as to a preparation method and an application thereof.

BACKGROUND

At present, the main method for the preparation of titanate nanomaterials, and its subsequent products of titanic acid nanomaterials and TiO₂nanomaterials is the strong alkaline hydrothermal method. However, this reaction requires the use of a high-pressure reaction vessel. Generally, titanate (e.g., sodium titanate) nano-tubes is firstly obtained by a long period of hydrothermal synthesis under high-temperature and high-pressure conditions by using commercial nano TiO₂and a high concentration of strong alkalis (e.g., NaOH solution) as raw materials, then titanic acid nanotubes is obtained by a neutralization and acid washing process, and then TiO₂nanotubes is obtain by a furthermore heat treatment. For example, in 2001, it was reported that titanic acid nanotubes with a tube length of tens to hundreds of nanometers and an inner diameter of 5.3 nm could be obtained by hydrothermal reaction of anatase-type TiO₂and a 10 mol/L sodium hydroxide solution in a high-pressure vessel at 130° C. for 72 h, followed by water washing of the product to neutrality. Other methods reported in the literature for the preparation of sodium titanate nanoparticles also include: weighing NaOH, TiO₂according to a stoichiometric relationship and then transferring them into a polytetrafluoroethylene high-pressure reactor, mixing them and holding them at a temperature of 230° C. for 48 h to 96h, and then removing them when they are cooled down to room temperature, washing and drying them to obtain sodium titanate nanomaterials, and further acid washing them to obtain titanic acid nanomaterials. It can be seen that the traditional hydrothermal method with strong alkali is characterized by 1) using TiO₂as the titanium source; 2) being carried out in a high-pressure reaction vessel, which requires airtight and high-pressure conditions; 3) being carried out at higher temperatures; 4) requiring a very long reaction time in terms of hours or tens of hours; and 5) the products obtained are generally nano-tubular titanates or nano-tubular titanic acid. These features, especially the use of TiO₂as the titanium source, which requires a high-pressure confined environment with an extremely long reaction time, seriously increase the production cost and reduce the production efficiency, which in turn hinders the large-scale and widespread application of titanate nanomaterials, titanic acid nanomaterials, and TiO₂nanomaterials.

In addition, dopant elements or dopant nanoparticles have a very important impact on the functional applications of nano-scale titanate, nano-scale titanic acid, and nano-scale TiO₂. Currently, the common method used for elemental doping into nano-scale titanate, nano-scale titanic acid, and nano-scale TiO₂is the mixing method, i.e., after preparing the above mentioned matrix materials, nanoparticles consisting mainly of the dopant elements prepared by other methods are then mixed with the above mentioned matrix materials, so as to make the dopant nanoparticles adsorbed on the surface of the matrix. This mechanical mixing-adsorption method is not only unfavorable for the physical-chemical interaction between the nanoparticles and the matrix material at the atomic scale, but also easily leads to the detachment of the doped nanoparticles from the surface of the aforementioned matrix, resulting in the instability and deterioration of the material properties.

SUMMARY

Based on this, it is necessary to provide a method for the preparation of nano-scale titanate, nano-scale titanic acid, and nano-scale TiO₂containing dopant elements through a simple process with rapid and efficient reaction under mild conditions, which is suitable for large-scale production, in view of the aforementioned technical problems.

It should be noted at the outset that in all technical examples of the present invention, the doping means that the corresponding E-group elements including Ag element is chimerically compounded with the corresponding doped matrix material by means of atoms or atomic clusters;

The content of the present invention sequentially includes twenty-five aspects related to the main claims and sequentially corresponds to the content of claims 1-25 as stated in the claims, specifically:

In the first aspect, a method of preparing a E-doped titanate nanofilm material, comprising the following steps:

- step 1, providing an initial alloy comprising T-type elements, Ti and E-group elements; wherein the T-type elements comprise at least one of Al and Zn; and the phase composition of the initial alloy comprises a T-Ti intermetallic compound with solid dissolved E-group elements; wherein the atomic percentage content of Ag in the E-group elements is 50%˜100%, and the molar ratio of E-group elements to Ti in the initial alloy is 0<C_E/C_Ti≤0.25;
- step 2, reacting the initial alloy with an alkaline solution at a temperature of T₁, during which the reaction interface advances inwardly from the surface of the initial alloy at an average rate of greater than 2 μm/min, and the initial alloy at the reaction interface undergoes nano-fragmentation through a hydrogen generation and T-removal reaction, and simultaneously undergoes shape and compositional reconfiguration to generate solid flocculent products containing E-group elements;
- step 3, the temperature of the solid flocculent product containing E-group elements in the reaction system described in step 2 is reduced from T₁and the solid flocculent product containing E-group elements is collected, i.e., the E-doped titanate nanofilm material is obtained.

Furthermore, the thin film material, macroscopically viewed in the form of a powder material, is microscopically observed to consist of a large number of two-dimensional thin films.

Furthermore, the thin film material, macroscopically viewed as a powder material, microscopically observed to be composed of a large number of monolithic two-dimensional thin films dispersed or entangled, the structure of which is completely different from that of the nanoporous structure formed by the conventional dealloying reaction. The nanoporous structure obtained by the conventional dealloying reaction consists of a three-dimensional network of ligaments connected to form a whole, and its overall appearance is basically the same as that of the initial alloy before the dealloying reaction;

Furthermore, the two-dimensional thin-film material means a material in which the smallest unit of the material (e.g., a monolithic film) has a large area and its dimension in the thickness direction is much smaller than the two-dimensional dimensions in the area direction, and its thickness does not exceed 10 nm.

Furthermore, the doping E-group elements, is the usual expression in the field of chemistry, whereas the E-group elements are not necessarily impurity elements, this is relative to the concept of the matrix material on which they are dependent, that is, the E-group elements are elements that are inconsistent with the composition of the matrix material, and the elements have a special function, for the purpose of purposely designing and adding, so as to achieve a homogeneous composite with the matrix material, and to achieve a certain purpose;

In the step 1:

Furthermore, the T-type elements include Al; Furthermore, the T-type element is Al;

Furthermore, the T-type elements include Zn; Furthermore, the T-type element is Zn;

Furthermore, the T-type elements include Al and Zn;

Furthermore, the E-group elements are predominantly Ag; as a preference, the E-group element is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also comprise other elements capable of being solid dissolved in Ag or the T-Ti intermetallic compound, thereby the E-group elements can exist as solid solution in the T-Ti intermetallic compound in the initial alloy;

Furthermore, the T-Ti intermetallic compound is equivalent to the Ti-T intermetallic compound;

Furthermore, when not all of the E-group elements are Ag, the E-group elements further include at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir;

Furthermore, the solid solution, includes an interstitial solid solution and a displacement solid solution method;

Furthermore, the T-Ti intermetallic compound with E-group elements in solid solution means that the E-group elements exist in the lattice interstices of the T-Ti intermetallic compound in the manner of interstitial atoms, or the E-group elements displace T atom positions or Ti atom positions in the lattice of the T-Ti intermetallic compound in the manner of displacement atoms;

Furthermore, wherein the T refers to T-type elements, is a shorthand for T-type elements, and wherein T represents any one of Al, Zn, AlZn, and wherein there is no limit to the ratio of Al to Zn in AlZn;

Furthermore, the molar ratio content of E-group elements solid dissolved in the T-Ti intermetallic compound to Ti in the initial alloy is represented by C_E/C_Ti, wherein 0<C_E/C_Ti≤0.25;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the initial alloy is prepared by solidifying a melt containing T-type elements, Ti and E-group elements, and during the solidification of the alloy a solidification structure is formed containing T-Ti intermetallic compounds; the E-group elements are mainly solid dissolved in the T-Ti intermetallic compounds.

Furthermore, the T-Ti intermetallic compound is equivalent to the Ti-T intermetallic compound;

Furthermore, the initial alloy melt solidifies at a rate of 1 K/s to 10⁷K/s;

Furthermore, the phase composition of the initial alloy consists mainly of T-Ti intermetallic compounds with E-group elements solid dissolved;

Furthermore, the T-Ti intermetallic compound includes at least one of T₃Ti, T₂Ti, TTi intermetallic compound;

Furthermore, the T-Ti intermetallic compound includes at least one of Al₃Ti, Al₂Ti, AlTi intermetallic compound;

Furthermore, the initial alloy includes at least one of T₃Ti, T₂Ti, TTi intermetallic compounds solid dissolved with E-group elements;

Furthermore, the initial alloy includes at least one of Al₃Ti, Al₂Ti, AlTi intermetallic compounds having E-group elements in solid solution;

Furthermore, the initial alloy predominantly includes one of Al₃Ti, Al₂Ti, AlTi intermetallic compounds with E-group elements in solid solution;

As one of the preferred ones, the initial alloy mainly includes an Al₃Ti intermetallic compound with E-group elements solid dissolved therein;

As a second preference, the initial alloy mainly includes an Al₂Ti intermetallic compound with E-group elements solid dissolved;

As a third preference, the initial alloy mainly includes an AlTi intermetallic compounds with E-group elements solid dissolved;

As a preference, the initial alloy has an atomic percentage of T less than or equal to 75%;

As a preference, the atomic percentage of T in the initial alloy is less than 70%;

As a preference, the atomic percentage of Al in the initial alloy is less than or equal to 75%;

As a preference, the atomic percentage of Al in the initial alloy is less than 70%;

As a preference, the initial alloy does not contain a T phase;

As a preference, the initial alloy does not contain an Al phase;

Furthermore, according to the Al—Ti phase diagram, when the atomic percentage content of Al in the Al—Ti alloy exceeds 75%, the alloy generally contains the Al phase in the solidification structure; when the atomic percentage content of Al in the Al—Ti alloy is less than 75%, the alloy generally does not contain the Al phase in the solidification structure; According to the phase diagram, when TiAl₂is contained in the alloy, it can coexist with the TiAl phase or TiAl₃phase, but not with the Al phase, and therefore the alloy containing TiAl₂is unlikely to contain the Al phase;

Furthermore, the T-Ti intermetallic compound means that the phase composition of the intermetallic compound is a T-Ti intermetallic compound phase, i.e., the phase analysis of XRD for the T-Ti intermetallic compound is a T-Ti intermetallic compound including the intermetallic compound phase structure of T₃Ti, T₂Ti, TTi. At this time, the T-Ti intermetallic compound may contain other elements in addition to T and Ti, such as E-group elements in solid solution;

Furthermore, due to the relatively fixed element ratio relationship of the T-Ti intermetallic compounds, the main compositional ratio of the initial alloy can be roughly obtained based on the determined composition of the T-Ti intermetallic compounds, the composition of the E-group elements, and the molar ratio of the E-group elements to Ti;

For example, with Ag solid dissolved in the Al₃Ti intermetallic compound and C_Ag:C_Ti=0.04, the average composition of the initial alloy is roughly Al_74.258Ti_24.752Ag_0.99;

Furthermore, the average size of any one dimension in the three-dimensional direction of the initial alloy shape is greater than 4 μm;

Furthermore, the average size of any one dimension in the three-dimensional direction of the initial alloy shape is greater than 10 μm; Furthermore, the average size of any one dimension in the three-dimensional direction of the initial alloy shape is greater than 15 μm;

Furthermore, the initial alloy is in the form of a powder or a strip, and the powder particles or ribbons have a scale of less than 5 mm in at least one dimension in the three-dimensional direction;

Furthermore, the initial alloy powder particles or ribbons have a scale of less than 1 mm in at least one dimension in a three-dimensional direction;

Furthermore, the initial alloy powder particles or ribbons have a scale of less than 500 μm in at least one dimension in the three-dimensional direction;

As a preference, the initial alloy powder particles or ribbons have a scale of less than 200 μm in at least one dimension in the three-dimensional direction;

As a preference, the initial alloy powder particles or ribbons have a scale of less than 50 μm in at least one dimension in the three-dimensional direction;

Furthermore, when the initial alloy is in the form of a strip, it can be prepared by a method comprising the melt spinning method;

Furthermore, when the initial alloy is in the form of a powder, a larger initial alloy ingot can be prepared by a casting method, and then crushed into the initial alloy powder.

In the step 2:

Furthermore, the hydrogen generation and T-removal reaction is a reaction in which T is dissolved in a hot alkaline solution to from a salt, while hydrogen is released when the initial alloy is reacted with the hot alkaline solution at a temperature of T₁;

Furthermore, the alkaline solution comprises at least one of NaOH, KOH, LiOH, RbOH, Ba(OH)₂, Ca(OH)₂, Sr(OH)₂solution;

Furthermore, the solvent in the alkaline solution comprises water; as a preference, the solvent in the alkaline solution is water;

Furthermore, the concentration of alkali in the alkaline solution is 5.1˜25 mol/L;

As a preference, the concentration of alkali in the alkaline solution is 5.1˜15 mol/L;

As a preference, the concentration of alkali in the alkaline solution is 7˜15 mol/L; as a furthermore preference, the concentration of alkali in the alkaline solution is 7˜12 mol/L;

As a further preference, the concentration of alkali in the alkaline solution is 10˜15 mol/L;

Furthermore, the concentration of alkali refers to the concentration of OH⁻ in the alkaline solution;

Furthermore, the alkali in the hot alkaline solution reacting with the initial alloy is an overdose, and the volume of the hot alkaline solution is more than 5 times the volume of the initial alloy, so that the reaction can be proceed all the time at a higher alkaline concentration;

Furthermore, the volume of the hot alkaline solution is more than 10 times the volume of the initial alloy;

Furthermore, the volume of the hot alkaline solution is more than 20 times the volume of the initial alloy;

Furthermore, the temperature at which the initial alloy reacts with the alkaline solution is the temperature of the alkaline solution;

Furthermore, under a certain alkaline concentration condition, the temperature T₁of the alkaline solution is sufficient to ensure that the reaction interface advances inwardly from the surface of the initial alloy at an average rate of not less than 2 μm/min during the hydrogen generation and T-removal process and that the initial alloy can be nano-fragmented by the hydrogen generation and T-removal during the reaction process; in other words, the temperature T₁and the concentration of the alkaline solution are determined by the reaction rate, reaction time and reaction effect of the hydrogen generation and T-removal reaction (since the reaction rate and the initial alloy size is determined, then the reaction time is determined; the reaction time for hydrogen generation and T-removal is determined when the generated gas can't be observed by the naked eye); therefore, when the value of the reaction rate is used to confine the reaction, the temperature T₁and the concentration of the alkaline solution are indirectly confined.

Furthermore, the average rate of 2 μm/min is the critical reaction rate at which the initial alloy can undergo nano-fragmentation via the hydrogen generation and T-removal reaction during the reaction process;

Furthermore, the occurrence of nano-fragmentation means that the initial alloy is fragmented by the hydrogen generation and T-removal process into a single intermediate or product with a scale of less than 500 nm in at least one dimension in a three-dimensional direction;

Furthermore, T₁≥60° C.;

Furthermore, the reaction of the initial alloy with the alkaline solution is carried out at ambient pressure or high pressure;

Furthermore, the reaction of the initial alloy with the alkaline solution is carried out in a closed vessel;

Under a closed vessel, high pressure is defined when the pressure inside the vessel exceeds one atmosphere; also, additional high pressure can be formed if the gases generated by the reaction inside the vessel cannot be discharged.

Furthermore, when the reaction is carried out in the closed vessel, the initial alloy and the alkaline solution are first placed separately in the closed vessel, and when the temperature of the alkaline solution reaches a set reaction temperature, the initial alloy is then contacted with the alkaline solution and the reaction starts.

Furthermore, the temperature of the alkaline solution may exceed its boiling point temperature at ambient pressure within the airtight container;

Furthermore, the reaction of the initial alloy with the hot alkaline solution is carried out at ambient pressure;

Furthermore, the ambient pressure, is the atmospheric ambient air pressure without the use of a closed container; furthermore, if the container is not tightly closed, although the pressure inside the container is slightly higher than the ambient pressure in a completely open environment, the pressure at this time also falls into the category of ambient pressure as it is also a non-closed environment.

Furthermore, the reaction is carried out in an atmospheric pressure environment, and atmospheric pressure generally refers to 1 standard atmospheric pressure, wherein the boiling point of the corresponding water is 100° C.; when there is an alkali dissolved in the water, the boiling temperature of the aqueous solution of the alkali is higher than 100° C. under 1 standard atmospheric pressure, and the higher the concentration of the alkali is, the higher the boiling point is. For example, the boiling point of T_{f solution}for the 5.1 mol/L sodium hydroxide aqueous solution is about 108° C.; the boiling point of T_{f solution}for the 7 mol/L sodium hydroxide aqueous solution is about 112° C.; the boiling point of T_{f solution}for the 10 mol/L sodium hydroxide aqueous solution is about 119° C.; the boiling point of T_{f solution}for the 12 mol/L sodium hydroxide aqueous solution is about 128° C.; the boiling point of T_{f solution}for the 15 mol/L sodium hydroxide aqueous solution is about 140° C.; the boiling point of T_{f solution}for the 17 mol/L sodium hydroxide aqueous solution is about 148° C.; the boiling point of T_{f solution}for the 20 mol/L sodium hydroxide aqueous solution is about 160° C.; the boiling point of T_{f solution}for the 25 mol/L sodium hydroxide aqueous solution is about 180° C.; The boiling point of T_{f solution}for the 10 mol/L potassium hydroxide aqueous solution is about 125° C.; the boiling point of T_{f solution}for the 12 mol/L potassium hydroxide aqueous solution is about 136° C.; the boiling point of T_{f solution}for the 15 mol/L potassium hydroxide aqueous solution is about 150° C.;

Furthermore, 60° C.≤T₁≤T_{f solution}, wherein the T_{f solution}is the boiling point temperature of the solution of the alkali involved in the reaction at ambient pressure;

Furthermore, 66° C.≤T₁≤T_{f solution}; Furthermore, 71° C.≤T₁≤T_{f solution}; Furthermore, 76° C.≤T₁≤T_{f solution};

Furthermore, 81° C.≤T₁≤T_{f solution}; Furthermore, 86° C.≤T₁≤T_{f solution}; Furthermore, 91° C.≤T₁≤T_{f solution};

Furthermore, 96° C.≤T₁≤T_{f solution}; Furthermore, 100° C.≤T₁≤T_{f solution}; Furthermore, 100° C.≤T₁≤T_{f solution};

Furthermore, 101° C.≤T₁≤T_{f solution}; Furthermore, 105° C.≤T₁≤T_{f solution};

Furthermore, 101° C.≤T_{f solution}−5° C.≤T₁≤T_{f solution};

Furthermore, 101° C.≤T_{f solution}−2° C.≤T₁≤T_{f solution};

As a further preference, the temperature of the alkaline solution is T_{f solution}, i.e. T₁=T_{f solution};

Since the highest temperature to which the reaction solution can be heated at ambient pressure is its boiling point temperature (T_{f solution}), when the temperature reaches this temperature and continues to be heated, the temperature of the solution does not increase. Therefore, the boiling point temperature is the easiest, simplest, and most accurate to control. Moreover, the reaction time required for the boiling point temperature reaction under the same conditions is also shorter than that required for other temperatures below the boiling point, and the product yield and efficiency are also the highest;

Furthermore, when 60° C.≤T₁≤100° C., the alkaline solution includes KOH;

Furthermore, when 60° C.≤T₁≤100° C., the concentration of KOH in the alkaline solution is not less than 2 mol/L; at this time, other OH⁻ can be provided by other alkalines to ensure that the total OH⁻ concentration reaches 5.1 mol/L or more;

Furthermore, when 60° C.≤T₁≤100° C., the alkaline solution mainly includes an aqueous KOH solution;

Furthermore, when 60° C.≤T₁≤100° C., the alkaline solution is an aqueous KOH solution;

Since T elements (Al, Zn) are amphoteric metals, they can react with hydroxide in hot concentrated alkaline solution to become T salts and dissolve in the solution while releasing hydrogen vigorously; therefore, the T in the initial alloy can be removed through the reaction of T with the hot alkaline solution, and the remaining E-group elements and Ti in the initial alloy can interact with the alkaline solution and undergo a series of simultaneous changes including diffusion and rearrangement of Ti atoms and their interaction with E-group elements, hydrogen, oxygen, OH⁻, and cations in the alkali, and then generate titanate nanofilms containing E-group elements through shape and compositional reconfiguration.

Furthermore, the reaction of the initial alloy with hot alkaline solution at 60° C.≤T₁≤T_{f solution}is important for the preparation of the product with a microscopic morphology of thin film. In one comparative example, when the initial TiAl₃intermetallic alloy powder solidly dissolved with Ag is reacted with a NaOH solution of 10 mol/L and at 35° C. for 2 h at ambient pressure, the shape of the original initial alloy powder before and after the reaction is substantially unchanged, and it remains as the original crushed and angular powdery particles. It also does not generate a large number of monolithic two-dimensional film-like products in the microstructure, but generates nanoporous structure of titanate or titanium through the three-dimensional network connection, which maintains the similar microstructure to the original alloy powder, including the angular shape; the size of their particle size is comparable to the size of the initial alloy powder, mainly in several microns or tens of microns level. Thus, the reaction of the initial alloy with the alkaline solution occurring at a lower temperature or near room temperature is completely different from the reaction of the present invention occurring at 60° C.≤T₁≤T_{f solution}, especially in the high temperature range, and the morphology of the products is also completely different.

Specifically, when the reaction temperature is taken in the low value range of 60° C.≤T₁≤T_{f solution}, i.e. in the range of 60° C.≤T₁≤100° C., and the alkaline solution mainly consists of an aqueous NaOH solution, the yield of the target product of titanate nanofilms doped with E-group elements is low. However, when the alkaline solution contains KOH, and the titanate nanofilm matrix doped with E-group elements includes a potassium titanate nanofilm matrix, the yield of the E-doped titanate nanofilm in the product can be substantially increased; for example, when the alkaline solution mainly consists of KOH aqueous solution and the reaction temperature is 60° C., the yield of the target product of E-doped potassium titanate nanofilm in the obtained product is not less than 50%; when the reaction temperature is 71° C., the yield of the target product of E-doped potassium titanate nanofilm in the obtained product is not less than 65%; when the reaction temperature is 81° C., the yield of the target product of E-doped potassium titanate nanofilm in the obtained product is not less than 75%; when the reaction temperature is 91° C., the yield of the target product of E-doped potassium titanate nanofilm in the obtained product is not less than 85%; when the reaction temperature is 96° C., the yield of the target product of E-doped potassium titanate nanofilm in the obtained product is not less than 90%;

When the reaction temperature is taken in the high value range of 60° C.≤T₁≤T_{f solution}, i.e. 100° C.≤T₁≤T_{f solution}, regardless of the type of alkali, the yield of E-doped titanate nanofilms in the resulting product is very high, and the product morphology is completely different from that of the original initial alloy powder particles or ribbons shape; for example, when the reaction temperature is higher than 101° C., a high yield of E-doped titanate nanofilms can be obtained, which is generally 95°˜100%; when the reaction temperature is taken as the boiling point T_{f solution}of the alkaline solution at atmospheric pressure, a higher yield of the E-doped titanate nanofilm can be obtained, and the yield is generally 99°˜100%;

In particular, when the reaction occurs at ambient pressure and at the boiling point temperature T_{f solution}of the alkaline solution, the solution composition of the reaction system has an obvious special change, which is manifested in the following: in the temperature interval below the boiling point temperature of the alkaline solution, the solvent mainly exists as liquid water; however, near or at the boiling point temperature, the solvent contains water that is undergoing a transformation from liquid to gas, in addition to the liquid water and the gaseous water produced by boiling. Moreover, due to the presence of reactants in solution and as formed nano-scale products, according to the principle of heterogeneous nucleation, it provides a large number of plasmas for boiling and evaporation, so that the reaction system is in a special environment of complete boiling and evaporation. In this special environment, the content and state of dissolved atmospheric gases (oxygen, nitrogen) in water are also extremely specific (because the large number of boiling water vapor, hydrogen generated by the reaction of T and alkalis, changes the saturation partial pressure conditions of dissolved gases in water). At the same time, the Ti-T intermetallic compounds with E-group elements solid solution react with the concentrated alkaline, and a large amount of hydrogen generates in the T-removal process of the alloy. The violent expansion effect caused by the hydrogen generated within a short period of time will promote the nano-fragmentation and shape and composition reconfiguration of the initial alloy at the reaction interface, and the T salts dissolved in alkaline solutions also change the composition of the reacting solution system. The T salts dissolved in alkaline solutions also change the composition of the reaction solution system. All of these characteristics of solutions at boiling point temperatures provide a very specific reaction environment for the reaction. Under this special reaction environment condition, a special reaction process will occur. The initial alloy will undergo a nano-fragmentation and a shape and composition reconfiguration process with high efficiency, which makes it difficult to stabilize the three-dimensional network-like continuous nanoporous structure usually generated by the dealloying reaction at low- or room-temperature. And instead, this process can produce a flocculent solid product mainly composed of two-dimensional titanate nanofilms doped with E-group elements. This not only greatly reduces the preparation time of the target thin film-like product, but also achieves a high yield of E-doped titanate nanofilms. Moreover, due to the constant boiling point temperature of the specific alkaline solution, the temperature control can be extremely precise, making the control of product morphology and composition extremely accurate and easy.

Furthermore, since the process of “nano-fragmentation—shape and composition reconfiguration of product” described in the step 2 occurs almost simultaneously with the reaction of “hydrogen generation and T-removal process”, the theoretical minimum time required for the product generation process described in the step 2 is the time required for the initial alloy reaction interface to advance inward from the surface to complete the hydrogen generation and T-removal reaction, which can be determined by the end of hydrogen generation.

Furthermore, the hydrogen generation reaction is a vigorous hydrogen generation reaction;

Furthermore, the vigorous hydrogen generation and T-removal reaction means that the rate of advancement of the reaction interface of the hydrogen generation and T-removal reaction is sufficiently fast that the hydrogen evolved from the reaction interface is concentrated to be released in a very short period of time, thus behaving as a vigorous reaction process.

Furthermore, the degree of vigor of the hydrogen generation and T-removal reaction is related to the rate of reaction advancement of the reaction interface from the initial alloy surface inwardly per unit time, the higher the temperature of the alkaline solution, the faster the rate of advancement of the reaction interface is, and the more violent the reaction is.

Furthermore, the reaction interface advances inwardly from the initial alloy surface at an average rate of greater than 4 μm/min; Furthermore, the reaction interface advances inwardly from the initial alloy surface at an average rate of greater than 7.5 μm/min;

Furthermore, the reaction interface advances inwardly from the initial alloy surface at an average rate of greater than 17.5 μm/min;

Furthermore, when 60° C.≤T₁≤100° C., the reaction interface advances inwardly from the initial alloy surface at an average rate of greater than 2 μm/min;

Furthermore, when 100° C.≤T₁≤T_{f solution}, the reaction interface advances inwardly from the initial alloy surface at an average rate of greater than 20 μm/min;

For example, when the alkali concentration is 10 mol/L, the advancement rate of the reaction interface from the surface of the initial alloy inward during the reaction of the Ag₁Ti₂₅Al₇₄initial alloy with the alkaline solution is as follows:

- 60° C.<T₁≤71° C., the reaction interface has an average advancement rate of about 2.5 μm/min˜4.0 μm/min;
- 71° C.<T₁≤81° C., the reaction interface has an average advancement rate of about 4.0 μm/min˜7.5 μm/min;
- 81° C.<T₁≤91° C., the reaction interface has an average advancement rate of about 7.5 μm/min˜17.5 μm/min;
- 91° C.<T₁≤100° C., the reaction interface has an average advancement rate of about 17.5 μm/min˜35 μm/min;
- 100° C.<T₁≤110° C., the reaction interface has an average advancement rate of about 35 lam/min˜60 μm/min;
- 110° C.<T₁≤120° C., the average advancement rate of the reaction interface is about 60 μm/min˜125 μm/min;
- 120° C.<T₁≤T_{f solution}, the average advancement rate of the reaction interface is greater than 120 μm/min;

Since T elements (Al, Zn) are amphoteric metals, their reaction with alkaline solutions near the boiling point temperature (which is higher than 100° C.) at ambient pressure is very rapid. In general, the reaction time for the complete removal of T elements from the initial alloy is related to the shape of the initial alloy. The smaller the initial alloy powder particles or the thinner the initial alloy ribbons, the shorter the time required for completion of the hydrogen generation and T-removal reactions; conversely, the longer the time required for the completion of the hydrogen generation and T-removal reactions.

Furthermore, ultrasound is applied during the hydrogen generation and T-removal to further enhance the nano-fragmentation effect and reaction rate by ultrasound treatment;

Furthermore, the frequency of the ultrasound is from 20 kHz to 10⁶kHz;

According to the average advancement rate of the reaction interface and the size of the initial alloy, the minimum reaction time required for the completion of the hydrogen generation and T-removal reactions can be calculated as t. For example, when the initial alloy is a strip with a thickness of d, and the average advancement rate of the reaction interface is v, taking into account the fact that the reaction interface advances from the upper and lower surfaces of the strip, t=0.5 d/v; similarly, when the initial alloy is a granular alloy with a diameter of d and the average advancement rate of the reaction interface is v, t=0.5 d/v.

In one embodiment, the initial alloy ribbon of TiAl₃intermetallic compound solid dissolved in Ag reacts with a NaOH solution of 10 mol/L and at a boiling temperature of about 119° C. The average advancement rate of the reactive interface of the initial alloy ribbon is about ˜120 μm/min, i.e., for a 40 μm-thick initial alloy ribbon, the hydrogen generation and Al-removal reactions can be finished in 10 s; for a 20 μm-thick initial alloy ribbon, the hydrogen generation and Al-removal reactions can be finished in 5 s; and even if the initial alloy balls of a grain size of 5 mm, the hydrogen generation and Al-removal reactions of the initial alloy balls can be finished in 21 min;

In one embodiment, a initial alloy ribbon comprised TiAl₃intermetallic compound and Ag solid solution is reacted with a 10 mol/L NaOH solution at its boiling temperature (the boiling temperature of about 119° C.), and the average advancement rate of the reactive interface of the initial alloy ribbon is about ˜120 μm/min, i.e., for a 40 μm-thick initial alloy ribbon, the hydrogen generation and Al-removal reactions can be completed in 10 s; for a 20 μm-thick initial alloy ribbon, the hydrogen generation and Al-removal reactions can be completed in 5 s. Even for an initial alloy ball with a diameter of 5 mm, the hydrogen generation and Al-removal reactions can be completed in 21 min;

When the d is about 40 μm, the preparation of its corresponding initial alloy is extremely simple, and it can be easily prepared by the ordinary melt spinning method, and according to t=0.5 d/v, even if the average advancement rate of the reaction interface is 2.5 μm/min corresponding to the low-temperature interval of 60° C., the hydrogen generation and T-removal reactions can be completed in 8 min;

When the hydrogen generation and T-removal reaction is completed, the reaction system subsequently reaches equilibrium; at this time, continue to extend the holding time of the reaction system at the original reaction temperature can still ensure the stability of the product. Thus, when the reaction time of the initial alloy with the hot alkaline solution exceeds the minimum required time t for hydrogen generation and T-removal reaction, e.g. up to several hours, the corresponding product can still be obtained;

Furthermore, the minimum reaction time of the initial alloy with the alkaline solution at temperature T₁is 10 s;

Furthermore, the reaction time of the initial alloy with the hot alkaline solution at T₁temperature is 10 s˜59 min;

Furthermore, the reaction time of the initial alloy with the hot alkaline solution at T₁temperature is 10 s˜29 min; Furthermore, the reaction time of the initial alloy with the hot alkaline solution at T₁temperature is 10 s˜9.9 min;

Furthermore, the reaction time of the initial alloy with the hot alkaline solution at T₁temperature is 10 s˜4.9 min;

Furthermore, the reaction time of the initial alloy with the hot alkaline solution at T₁temperature is 10 s˜2 min;

Furthermore, the reaction time of the initial alloy with the hot alkaline solution at T₁temperature is 10 s˜1 min;

Furthermore, the reaction time of the initial alloy with the hot alkaline solution at T₁temperature is 10 s˜30 s;

Obviously, when T₁is higher and the initial alloy is thinner or the particle size is smaller, the shorter the reaction time required; conversely, the longer the reaction time;

Furthermore, the occurrence of nano-fragmentation means that the initial alloy at the reaction interface is fragmented into nanoscale intermediates or products by the hydrogen generation and T-removal reactions, and at the same time, two-dimensional titanate nonofilms containing E-group elements are generated by the shape and composition reconfiguration; in this process, the hydrogen released violently by the hydrogen generation and T-removal reactions promotes the nano-fragmentation of the intermediates and products, the shape and composition reconfiguration of the products, and the diffusion distribution of the products in the alkaline solution after leaving the reaction interface.

Furthermore, the occurrence of nano-fragmentation means that the initial alloy at the reaction interface is fragmented by the hydrogen generation and T-removal reactions into individual intermediates or products having a scale of less than 500 nm in at least one dimension in the three-dimensional direction;

Furthermore, the solid flocculent product containing E-group elements consists mainly of individual intermediates or products having a scale of less than 20 nm in at least one dimension in the three-dimensional direction;

Furthermore, the solid flocculent product containing E-group elements consists primarily of a single intermediate or product having a scale of less than 10 nm in at least one dimension in a three-dimensional direction;

Furthermore, the solid flocculated product containing E-group elements, after being generated by shape and composition reconfiguration, does not remain at the initial alloy reaction interface, but leaves the initial alloy reaction interface by diffusion during generation and is further diffused and distributed in the alkaline solution by thermal diffusion and convection of the alkaline solution liquid;

Furthermore, the shape and compositional reconfiguration means that the hydrogen generation and T-removal reactions of the initial alloy and the intermediate product after nano-fragmentation undergo further shape and compositional changes simultaneously, generating a nano-sized product with a completely different composition and shape from that of the initial alloy on the micrometer or millimeter scale; the dimensions of the nanoscale product are described in the subsequent description of step 3;

Furthermore, the as-prepared titanate nanofilms containing E-group elements do not contain a three-dimensional continuous network-like nanoporous structure or a porous skeletal structure;

Furthermore, the hydrogen generation and T-removal reactions transforms the micrometer or even millimeter-sized initial alloy into a large number of two-dimensional titanate nanofilms containing E-group elements through a step-by-step nano-fragmentation process from the surface inwards;

Furthermore, the solid flocculent product containing E-group elements mainly consists of a large number of two-dimensional titanate nanofilms containing E-group elements combined by aggregation and entanglement with each other; which macroscopically appears as a solid flocculent product;

Furthermore, the flocculent solid-state product means that the nanoscale scale thin film-like product is in the form of a solid-state flocculant after agglomeration during diffusion, and can be suspended in solution for a longer period of time from an observational point of view.

In the step 3: In general, after the temperature and products of a chemical reaction have reached equilibrium, if the temperature of the reaction system is slowly lowered, holding the reaction at the new temperature for a long time leads to a disruption of the original reaction equilibrium, with potential changes in the composition and morphologies of the reaction products.

The reaction system described in step 2 comprises the product generated by the reaction and the alkaline solution after the reaction;

In order to maintain the product of the initial reaction equilibrium in the hot alkaline solution while facilitating solid-liquid separation of the product, step 3 comprises a process of lowering the temperature of the solid flocculent product in the reaction system described in step 2 from T₁to a lower temperature interval. By controlling the rate of temperature reduction, the composition and morphology of the products formed at 60° C.≤T₁temperature, in particular the temperature interval of 100° C.<T₁, can be maintained by rapidly reducing the temperature of the reaction system, which makes it difficult for the reaction products to undergo corresponding changes in time.

Furthermore, the composition and morphology of the products formed at 60° C.≤T₁≤T_{f solution}temperature, in particular the temperature interval of 100° C.≤T₁≤T_{f solution}, can be maintained.

Furthermore, the temperature of the solid flocculent product containing E-group elements in the reaction system described in step 2 is reduced from T₁to a lower temperature interval at atmospheric pressure, wherein 60° C.≤T₁≤T_{f solution};

Furthermore, 66° C.≤T₁≤T_{f solution}; Furthermore, 71° C.≤T₁≤T_{f solution}; Furthermore, 76° C.≤T₁≤T_{f solution};

Furthermore, 81° C.≤T₁≤T_{f solution}; Furthermore, 86° C.≤T₁≤T_{f solution}; Furthermore, 91° C.≤T₁<T_{f solution};

Furthermore, 96° C.≤T₁≤T_{f solution}; Furthermore, 100° C.≤T₁≤T_{f solution}; Furthermore, 100° C.<T₁≤T_{f solution};

Furthermore, 101° C.≤T₁≤T_{f solution}; Furthermore, 105° C.≤T₁≤T_{f solution};

Furthermore, 101° C.<T_{f solution}−5° C.≤T₁≤T_{f solution};

Furthermore, 101° C.≤T_{f solution}−2° C.≤T₁<T_{f solution};

Furthermore, T₁=T_{f solution};

Furthermore, reducing the temperature of the solid flocculent product containing E-group elements in the reaction system described in step 2 from T₁to below 45° C.;

Furthermore, reducing the temperature of the solid flocculent product containing E-group elements in the reaction system described in step 2 from T₁to below 35° C.;

Furthermore, reducing the temperature of the solid flocculent product containing E-group elements in the reaction system described in step 2 from T₁to below 30° C.;

Furthermore, reducing the temperature of the solid flocculent product containing E-group elements in the reaction system described in step 2 by a cooling rate of greater than 5 K/s;

Furthermore, the rate of temperature reduction is greater than 10 K/s; Furthermore, the rate of temperature reduction is greater than 20 K/s; Furthermore, the rate of temperature reduction is greater than 50 K/s;

Furthermore, the required time for the temperature reduction of the reaction system described in step 2 in the solid flocculent product containing E-group elements is less than 20 s;

Furthermore, the required time for the temperature reduction is less than 10 s;

Furthermore, the required time for the temperature reduction is less than 5 s;

Furthermore, the required time for the temperature reduction is less than 2 s; It is understood that when the temperature interval of the reaction is in the high value range of the 60° C.≤T₁≤T_{f solution}temperature interval, such as the 100° C.≤T₁≤T_{f solution}temperature interval or the T_{f solution}temperature, the rapid reduction of the temperature of the reaction product by step 3 can ensure the stabilization of the composition and morphology of the product.

Furthermore, the methods of lowering the temperature of the solid flocculent product containing E-group elements in the reaction system described in step 2 includes at least one of the following: adding solvent to dilute, filtering and cooling;

At ambient pressure, since the reaction is carried out in an open vessel, the temperature of the solid flocculent product in the reaction system described in step 2 can be rapidly lowered by adding a cold solvent (e.g., water) to the reaction system and simultaneously lowering the concentration of the alkaline solution in the reaction system; as another way, the hot alkaline solution in the reaction system and the solid flocculent product containing E-group elements can also be rapidly poured out and simultaneously filtrating the flocculent product to separate it, thereby rapidly lowering the temperature of the solid flocculent product containing E-group elements;

Furthermore, the solvent corresponding to the solvent addition for dilution includes water;

Furthermore, the temperature of the solvent corresponding to the solvent addition dilution is room temperature;

Furthermore, the temperature of the solvent corresponding to the solvent addition dilution is 0° C.˜30° C.;

Furthermore, the temperature of the solvent corresponding to the solvent addition dilution is 0° C.˜25° C.; Furthermore, the temperature of the solvent corresponding to the solvent addition dilution is 0° C.˜20° C.;

Furthermore, when the additive solvent for dilution is used, the temperature of the solid flocculent product containing E-group elements in the reaction system described in step 2 is reduced while the temperature of the alkaline solution is simultaneously lowered, and in addition the concentration of the alkaline solution in the reaction system described in step 2 is reduced;

Furthermore, the concentration of the alkaline solution after dilution is less than 0.25 times the original concentration; meanwhile, the temperature of the alkaline solution after the reduction of temperature is less than 50° C.;

As a preference, the concentration of the alkaline solution after dilution is 0.1 times or less of the original concentration; at the same time, the temperature of the alkaline solution after the reduction of temperature is lower than 45° C.

Furthermore, when filter cooling is taken to reduce the temperature, the specific steps are as follows: under atmospheric pressure, the solid flocculent product containing E-group elements and the alkaline solution at a temperature of 60° C.≤T₁≤T_{f solution}is poured on a cold filter, and the solid flocculent product containing E-group elements and the alkaline solution are separated by the filter; the heat of the solid flocculent product containing E-group elements is rapidly conducted away by the environment and the filter, and the temperature of the solid flocculent product containing E-group elements can be rapidly reduced to the low temperature range;

Furthermore, 101° C.≤T₁≤T_{f solution}; Furthermore, T₁=T_{f solution};

Furthermore, the temperature of the filter mesh is not higher than 30° C.;

Furthermore, the temperature of the filter mesh is not higher than 20° C.;

Furthermore, the temperature of the filter mesh is not higher than 10° C.;

Furthermore, the filter mesh plane is at an angle to the horizontal plane, so that after the hot alkaline solution including the solid flocculent product is poured into the filter mesh, it can be sufficiently filtered and cooled while flowing and spreading on the filter mesh;

Furthermore, the angle between the plane of the filter mesh and the horizontal plane is 15° to 75°,

Furthermore, the mesh aperture size of the filter mesh ranges from 5 μm to 1 mm;

Furthermore, the filter mesh includes a multi-layer filter mesh;

Furthermore, the filter mesh includes at least 4 layers;

Furthermore, the filter mesh includes a multi-layer filter mesh and the mesh pore size of each layer is inconsistent;

The solid flocculent products containing E-group elements are generally aggregated and entangled together to form a larger aggregation group, so they can be firstly separated by the filter mesh with a larger aperture; by means of a multi-layer filter mesh, primary separation of the solid products can be achieved by a larger mesh filter, continued separation of the solid flocculent products can be achieved by the medium-sized mesh filter, and final separation of the solid flocculent products can be achieved by the small mesh filter;

Furthermore, the filter mesh includes a metal filter with excellent thermal conductivity;

It can be understood that when cooling down the temperature by cold mesh filtration, not only the temperature of the solid flocculent product containing E-group elements is rapidly reduced, but also the separation of solid-liquid substances corresponding to the original reaction equilibrium occurs, which reduces the volume of the separated by-product solution as compared to the dilution method, and further ensures that the composition and morphology of the product generated by the T₁temperature are preserved, which is of positive significance.

Furthermore, as long as the temperature of the ultimately obtained E-doped titanate nanofilm material is lower than T₁, or it is subjected to solid-liquid separation, cleaning, preservation, and use at a temperature lower than T₁, regardless of the historical change of the temperature of the E-doped titanate nanofilm material in the intermediate process, it is part of the operation of reducing the temperature of the solid flocculent product containing E-group elements in the reaction system according to step 2 from T₁, as described in step 3;

Furthermore, the process of collecting the solid flocculent product containing E-group elements includes solid-liquid separation, washing, and drying of the solid flocculent product containing E-group elements;

Furthermore, collecting the solid flocculated product containing E-group elements, i.e., obtaining a two-dimensional E-doped titanate nanofilm material;

Furthermore, collecting the solid flocculent product containing E-group elements, i.e., obtaining the two-dimensional titanate nonofilm powder material doped with E-group elements.

Furthermore, the thin film material, macroscopically viewed in the form of a powder material, is microscopically observed to consist of a large number of two-dimensional thin films.

Furthermore, the E-doped titanate nanofilm material consists of a large number of aggregated single E-doped titanate nanofilm; it can be understood that a large number of single film can be softly agglomerated together by entanglement and aggregation with each other; Furthermore, the E-doped titanate nanofilm has a thickness of 0.25 nm to 7.5 nm;

Furthermore, the E-doped titanate nanofilm has a thickness of 0.25 nm to 4 nm;

Furthermore, the E-doped titanate nanofilm has a thickness of 0.25 nm to 3 nm;

Preferably, the E-doped titanate nanofilm has a thickness of 0.25 nm to 2 nm;

Furthermore, the average area of the E-doped titanate nanofilm is greater than 500 nm²;

As a preference, the average area of the E-doped titanate nanofilm is greater than 5000 nm²;

As a further preference, the average area of the E-doped titanate nanofilm is greater than 20,000 nm².

Furthermore, the titanate nanofilms doped with E-group elements are predominantly low crystallinity;

Furthermore, the cationic element in the E-doped titanate nanofilm is derived from the cationic element in the corresponding alkali;

Furthermore, the chemical composition of the E-doped titanate nanofilm material includes an E-group elements, Ti, O, and a corresponding cationic element in corresponding alkali; wherein the molar ratio of the E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25; for example, when the alkali is NaOH, the corresponding cationic element in the alkali is Na, and the titanate salt is sodium titanate, then the E-doped sodium titanate nanofilm material has a chemical composition including the E-group elements, Ti, O, and the element Na;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the E-group elements is mainly distributed in the titanate nanofilm in the form of atoms or atomic clusters;

Furthermore, when the E-group elements is distributed mainly as atoms or atomic clusters among the titanate nanofilms, the titanate nanofilms can be viewed as a single-phase material. In other words, the E-group elements, and other titanate constituent elements such as Ti, O, are uniformly distributed in the film as atoms or atomic clusters, and the E-group elements do not nucleate and grow into an E phase other than the titanate phase. At this time, the as-prepared product can be understood as a E-doped titanate nanofilm, or as a titanate nanofilm with the E-group elements solid dissolved, or as a completely new substance. For example, when the corresponding cationic element in the alkali is Na, such completely new substance can be considered as a titanate sodium (silver) nanofilm;

Furthermore, the E-group elements is mainly distributed in the titanate nanofilm in a embedding form as atoms or atomic clusters; the key feature of the embedding distribution is that the E-group elements is mainly confined in the titanate nanofilm as atoms or atomic clusters, and the atomic diffusion can only take place when a certain temperature is achieved; at the same time, due to the pinning effect of the E-group elements, it will greatly enhance the phase transition thermal stability of the titanate film matrix. For a detailed introduction, please refer to the following text corresponding to it.

Furthermore, when the E-group elements is present in the E-doped titanate nanofilm in the form of atoms or atomic clusters, due to the pinning effect of the atoms of the E-group elements, the thermal stability of the phase transition of the titanate nanofilm matrix can be increased by a maximum of 200° C.; and the higher the E content is, the higher the thermal stability of the phase transition is. That is, compared with the monolithic titanate nanofilm matrix, the heat treatment temperature of the E-doped titanate nanofilm needs to be increased by up to 200° C. to achieve the same phase transition during the heating process;

This increase in the thermal stability of the phase transition further indicates that the E-group elements is doped in the titanate matrix on an atomic or atomic cluster scale, rather than as an obvious E nanoparticle phase. If it present as an obvious E nanoparticle phase, and the titanate film matrix and the E nanoparticle phase are separate and independent phases, the phase transition thermal stability of the titanate matrix can not be greatly affected by the presence of E nanoparticle phase.

Furthermore, the process of collecting the solid flocculated product containing E-group elements in step 3 includes a drying process, whereby the powdered E-doped titanate nanofilm material is obtained by drying the solid flocculated product doped with E-group elements. Furthermore, the drying temperature is 50° C.˜350° C.; Furthermore, the drying temperature is 50° C.˜300° C.;

Furthermore, the drying time is 1 min˜24 h; Furthermore, the drying time is 5 min˜2 h; Furthermore, the drying time is in a low value range when the drying temperature is in a high value range;

Furthermore, the drying time is in a high value range when the drying temperature is in a low value range;

Since the E-group elements is mainly Ag, according to the characteristics of the Ag element, it is easy to oxidize into Ag₂O drying at treatment below 180° C., while the Ag₂O will decompose into Ag when the drying temperature is above 180° C., therefore:

Furthermore, when the drying temperature takes the low value of the range, the E-doped titanate nanofilm contains O-bound Ag atoms or Ag clusters;

As a preference, when the drying temperature is 50° C.˜180° C., the E-doped titanate nanofilm contains O-bound Ag atoms or Ag clusters;

As a preference, when the drying temperature is 50° C.˜180° C., the E-doped titanate nanofilm contains O-bound Ag₂O clusters;

Since the O—Ag bond will break and decompose at higher temperatures, when the drying temperature takes the high value of the range, the O that is bound with Ag will separate from Ag due to the breakage of the O—Ag bond;

Furthermore, when the drying temperature takes the high value of the range, the E-group elements are mainly distributed in the titanate nanofilm as atoms or atomic clusters;

As a preference, when the drying temperature is 181° C.˜350° C., the E-group elements are mainly distributed among the titanate nanofilm in the form of atoms or atomic clusters.

Therefore, the degree of bonding with Ag and O can be controlled by the control of the drying temperature and drying time.

Furthermore, when the drying temperature is lower than 350° C., the shape of the titanate film remains substantially unchanged and the E elements remain embedded and distributed in the titanate film as atoms or atomic clusters;

Furthermore, the atomic clusters containing E-group elements have a size of less than 1.5 nm;

Furthermore, the atomic clusters containing E-group elements have a size of less than 1 nm, and when the atomic clusters containing E-group elements are less than 1 nm, the size of such atomic clusters is insufficient to form E-phase nanoparticles that are distinguishable at the phase interface and it is difficult to distinguish the atomic clusters containing E-group elements from the matrix by means of observation, such as transmission electron microscopy (TEM); thus in this scale, it is uniformly distributed in the matrix.

Furthermore, the E-group elements are mainly distributed as atoms or atomic clusters in the titanate nanofilm;

Furthermore, the E-group elements are distributed in the titanate nanofilm mainly in the form of atoms.

Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%; Furthermore, the E-group elements is predominantly Ag;

Furthermore, the E-group elements is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also contain other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds; thereby allowing the E-group elements to be present in the original initial alloy in the Al—Ti intermetallic compound by solid solution;

Furthermore, when not all of the E-group elements are Ag, the E-group elements further include at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

Furthermore, the yield of the two-dimensional E-doped titanate nanofilm in the final product is its weight percent in the final product;

Furthermore, the yield of the E-doped titanate nanofilm in the final product is from 50% to 100%;

Furthermore, the E-doped titanate nanofilm has a yield of 65% to 100% in the final product;

Furthermore, the E-doped titanate nanofilm has a yield of 75% to 100% in the final product;

Furthermore, the E-doped titanate nanofilm has a yield of 85% to 100% in the final product;

Furthermore, the E-doped titanate nanofilm has a yield of 90% to 100% in the final product;

Furthermore, the E-doped titanate nanofilm has a yield of 95% to 100% in the final product;

Furthermore, the E-doped titanate nanofilm has a yield of 99% to 100% in the final product;

When the reaction temperature is taken in the high value range of 60° C.≤T₁≤T_{f solution}, i.e. 100° C.<T₁≤T_{f solution}, regardless of the type of alkali, the yield of E-doped titanate nanofilms in the resulting product is very high, and the product morphology is completely different from that of the original initial alloy powder particles or ribbons shape; for example, when the reaction temperature is higher than 101° C., a high yield of E-doped titanate nanofilms can be obtained, which is generally 95° 4˜100%; when the reaction temperature is taken as the boiling point T_{f solution}of the alkaline solution at atmospheric pressure, a higher yield of the E-doped titanate nanofilm can be obtained, and the yield is generally 99%˜100%;

In the second aspect, the present invention also relates to a method of preparing a titanate nanofilm material embedded with E nanoparticles, wherein the titanate nanofilm material embedded E nanoparticles is prepared by heat-treating the product or the E-doped titanate nanofilm material prepared according to the first aspect thereof.

The thermal stability of the titanate nanofilm will be improved due to the presence of the doped E-group elements, and the thickening and shrinkage of the film under heating will be hindered by the doped E-group elements. Therefore, the thickness of the titanate nanofilm does not change significantly (it maintains in a thin film state), by controlling the heat treatment temperature and time during the heat treatment process. While the doped E-group elements, which are mainly distributed in the titanate nanofilm in the form of atoms or atomic clusters, will transform into E nanoparticles embedded in the titanate nanofilm by elemental diffusion and aggregation. This kind of embedded E nanoparticles is different from the ordinary nanoparticles adsorbed through van der Waals force that is reported in other literatures (nanoparticles adsorbed through van der Waals force can move and detach from the substrate). This kind of embedded E nanoparticles ensure that the E nanoparticles can be tightly embedded within the titanate nanofilm (it cannot move or detach from the substrate). When all of the E-group elements, which are mainly distributed as atoms or atomic clusters, have been aggregated into E nanoparticles, it is difficult for them to continue to merge and grow due to the island-like distribution of the E nanoparticles, which cannot be connected by the spatial obstruction of the titanate nanofilm matrix. Therefor, the particle size of the E nanoparticles can be kept roughly unchanged during the subsequent heating process.

For example, a monolithic titanate nanofilm without E-group elements undergoes a phase transition by heat-treating at 450° C. for 1 h, while the titanate nanofilm containing high value of E-group elements still does not undergo a significant phase transition and shape change within the film matrix by heat-treating at 600° C. for 0.5 h; and the phase transition and shape change of the film matrix can not be obviously observed by heat-treating at 650° C. for 2 min.

Therefore, it is possible to take advantage of the improved thermal stability of the E-doped titanate nanofilm to promote the precipitate of the E nanoparticles through the diffusion and aggregation of the E-group elements in the film matrix by heat treatment, while the shape of the film does not change significantly;

Furthermore, the temperature of the heat treatment is 350° C.˜650° C.;

Furthermore, the temperature of the heat treatment is 350° C.˜600° C.;

Furthermore, the temperature of the heat treatment is 350° C.˜550° C.;

Furthermore, the time of the heat treatment is 2 min˜96 h; as a preference, the time of the heat treatment is 10 min˜5 h.

When a low value of the temperature range is selected and the content of the E-group elements is high, it takes a long time for the precipitate of the E nanoparticles through element diffusion and aggregation; when a high value of the temperature range is selected and the content of the E-group elements is low, it takes a shorter time for the precipitate of the E nanoparticles through element diffusion and aggregation;

Furthermore, the E nanoparticles have a size of 1.5 nm˜10 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜7.5 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜5 nm;

Furthermore, the E nanoparticles are present in the titanate nanofilm mainly by means of embeddedness;

The “embedding” refers to a formation mode of in situ generation, i.e., the E nanoparticles are aggregated, grown-up and formed in situ through the diffusion of the doping E-group elements; The embedded E nanoparticles are manifested as being partially or completely embedded in the titanate nanofilm matrix, which does not rely on external addition or external mixed methods to make it embedded.

Furthermore, the thickness of the titanate nanofilm with precipitated E nanoparticles after heat treatment is slightly greater than the thickness before heat treatment;

Furthermore, the thickness of the titanate nanofilm embedded with E nanoparticles is 0.3 nm˜10 nm;

Furthermore, the thickness of the titanate nanofilm embedded with E nanoparticles is 0.3 nm˜5 nm;

Furthermore, the thickness of the titanate nanofilm embedded with E nanoparticles is 0.3 nm˜4 nm;

Furthermore, the thickness of the titanate nanofilm embedded with E nanoparticles is 0.3 nm˜2 nm;

Furthermore, in addition to a volume portion embedded in the titanate nanofilm, the E nanoparticle has another volume portion that is not embedded in the film;

Since the embedded E nanoparticles are generated by the diffusion and aggregation of E-group elements originally distributed in the titanate nanofilm, they can be embedded and distributed in the film, and since the film is sufficiently thin, some of the E nanoparticles may have a exposed volume portion outside the film;

Furthermore, the average area of the titanate nanofilm embedded with E nanoparticles is greater than 400 nm²; preferably, the average area of the titanate nanofilm embedded with E nanoparticles is greater than 4,000 nm²; further preferably, the average area of the titanate nanofilm embedded with E nanoparticles is greater than 16,000 nm²; Furthermore, the main chemical composition of the titanate nanofilm material embedded with

E nanoparticles includes E-group elements, Ti, O, and the corresponding cationic element in the alkali, wherein the molar ratio of the E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%; Furthermore, the E-group elements is mainly Ag;

Furthermore, the E-group elements is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also contains other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also comprise at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

In the third aspect, the present invention also relates to a method of preparing an E-doped titanic acid nanofilm material, wherein the E-doped titanic acid nanofilm material is obtained by reacting the product or the E-doped titanate nanofilm material prepared according to the first aspect with an acid solution and then collecting the solid product.

By reacting with the acid solution, the residual alkali adsorbed on the surface of the E-doped titanate nanofilm material is first neutralized, and then ion exchange between the cations in the E-doped titanate nanofilm material and the hydrogen ions in the acid solution occurs to obtain an E-doped titanic acid nanofilm material. In addition, the as-prepared product is substantially identical to the main characteristics of the product described in the first aspect thereof;

Furthermore, the acid solution includes at least one of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, phosphoric acid, oxalic acid, picric acid, oleic acid, perchloric acid;

Since the two-dimensional E-doped titanate nanofilms or two-dimensional E-doped titanic acid nanofilms prepared by the present method are extremely thin, when the acid concentration is higher than 0.1 mol/L, further dissolution of the E-doped titanic acid nanofilm matrix in the acid solution occurs significantly. Therefore, in order to prevent further dissolution of the E-doped titanic acid nanofilm by reaction with the acid, the acid solution is a dilute acid solution, and the hydrogen ion concentration therein is lower than 0.1 mol/L;

As a preference, the hydrogen ion concentration in the acid solution is 0.0001 mol/L˜0.09 mol/L;

As a preference, the hydrogen ion concentration in the acid solution is 0.0001 mol/L˜0.05 mol/L;

As a Furthermore preference, the hydrogen ion concentration in the acid solution is 0.0001 mol/L˜0.01 mol/L.

Furthermore, the specific step of reacting the E-doped titanate nanofilm material with an acid solution is as follows: the E-doped titanate nanofilm material is dispersed in water, and the acid solution is gradually added while stirring so that the pH of the mixed solution continuously decreases. Finally, the pH of the mixed solution is controlled to be in the range of 2˜5, and after 1 min˜5 h, followed by separation and drying, then the E-doped titanic acid nanofilm is obtained. When the pH value is maintained between 2 and 5, corresponding to a concentration of hydrogen ions in the mixed solution is 0.00001 mol/L˜0.01 mol/L, it can be ensured that the residual alkali adsorbed on the surface of the E-doped titanate nanofilm material is first neutralized during the whole process, and then the ion exchange between the cations in the E-doped titanate nanofilm material and hydrogen ions in the acid solution takes place, thereby the E-doped titanic acid nanofilm material that has not reacted significantly with the acid solution is obtained.

Furthermore, the thickness of the E-doped titanic acid nanofilm is 0.25 nm˜7.5 nm; Furthermore, the thickness of the E-doped titanic acid nanofilm is 0.25 nm˜4 nm; as a preference, the thickness of the E-doped titanic acid nanofilm is 0.25 nm˜3 nm; as a preference, the thickness of the E-doped titanic acid nanofilm is 0.25 nm˜2 nm;

Furthermore, the average area of the E-doped titanic acid nanofilm is greater than 500 nm²; as a preference, the average area of the E-doped titanic acid nanofilm is greater than 5000 nm²; as a Furthermore preference, the average area of the E-doped titanic acid nanofilm is greater than 20000 nm²;

Furthermore, the titanic acid nanofilms doped with E-group elements are predominantly of low crystallinity;

Furthermore, the chemical composition of the E-doped titanic acid nanofilm material includes the E-group elements, To, H, and O elements; wherein the molar ratio of the E-group elements to T₁satisfies 0<C_E/C_Ti≤0.25;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the E-group elements is mainly distributed in the nano acid titanate film as atoms or atomic clusters;

Furthermore, when the E-group elements is distributed mainly as atoms or atomic clusters in the titanic acid nanofilm, the titanic acid nanofilm can be viewed as a single-phase material. That is, the E-group elements, and other titanate constituent elements such as Ti, H, O, are uniformly distributed in the film as atoms or atomic clusters, and the E-group elements do not nucleate and grow into the E nanoparticle phase in addition to the titanic acid phase. As a result, the as-prepared product can be understood as a titanic acid nanofilm doped with the E constituent elements, a titanic acid nanofilm with the E constituent elements solid dissolved, or a completely new substance such as a titanic acid (silver) nanofilm;

Furthermore, the E-group elements is mainly distributed in the titanate nanofilm in a embedding form as atoms or atomic clusters; the key feature of the embedding distribution is that the E-group elements is mainly confined in the titanic acid nanofilm in the form of atoms or atomic clusters, and the atomic diffusion can only take place when a certain temperature is achieved; at the same time, due to the pinning effect of the E-group elements, it will greatly improve the thermal stability of the titanic acid nanofilm matrix. For a detailed introduction, please refer to the following text corresponding to it.

Furthermore, when the E-group elements is present in the E-doped titanic acid nanofilm in the form of atoms or atomic clusters, due to the pinning effect of the atoms of the E-group elements, the thermal stability of the phase transition of the titanic acid nanofilm matrix can be increased by up to 200° C.; and the higher the content of E is, the higher the thermal stability of the phase transition is. That is, compared with the monolithic titanic acid nanofilm matrix, the heat treatment temperature of the E-doped titanic acid nanofilm needs to be increased by up to 200° C. to achieve the same phase transition during the heating process;

This increase in the thermal stability of the phase transition further indicates that the E-group elements is doped in the titanic acid matrix on an atomic or atomic cluster scale, rather than as an obvious E nanoparticle phase. If it present as an obvious E nanoparticle phase, and the titanic acid film matrix and the E nanoparticle phase are separate and independent phases, the phase transition thermal stability of the titanic acid matrix can not be greatly affected by the presence of E nanoparticle phase.

Furthermore, the process of collecting the solid product includes a drying process;

Furthermore, the drying temperature is 50° C.˜350° C.;

Furthermore, the drying temperature is 50° C.˜300° C.;

Furthermore, the drying time is 1 min˜24 h;

Furthermore, the drying time is 5 min˜2 h;

Furthermore, when the drying time is in a low value range, the drying temperature is in a high value range;

Furthermore, when the drying temperature is in a low value range, the drying time is in a high value range;

Furthermore, when the drying temperature takes the low value of the range, the E-doped titanic acid nanofilm contains O-bound Ag atoms or Ag clusters;

As a preference, when the drying temperature is 50° C.˜180° C., the E-doped titanic acid nanofilm contains O-bound Ag atoms or Ag clusters;

As a preference, when the drying temperature is 50° C.˜180° C., the E-doped titanic acid nanofilm contains O-bound Ag₂O clusters;

Furthermore, when the drying temperature takes the high value of the range, the E-group elements is mainly distributed in the titanic acid nanofilm as atoms or atomic clusters;

As a preference, when the drying temperature is 181° C.˜350° C., the E-group elements are mainly distributed among the titanic acid nanofilm in the form of atoms or atomic clusters.

Therefore, the degree of bonding with Ag and O can be controlled by the control of the drying temperature and drying time.

Furthermore, when the drying temperature is lower than 350° C., the shape of the titanic acid nanofilm remains substantially unchanged and the E elements remain embedded and distributed in the titanic acid nanofilm as atoms or atomic clusters;

Furthermore, the atomic clusters containing E-group elements have a size of less than 1.5 nm;

Furthermore, the E-group elements are mainly distributed as atoms in the titanic acid nanofilm.

Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%; Furthermore, the E-group elements is mainly Ag; the E-group elements is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also contain other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds;

Furthermore, when not all of the E-group elements are Ag, the E-group elements further include at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

In the fourth aspect, the present invention also relates to a method of preparing a titanic acid nanofilm material embedded with E nanoparticles, wherein the titanic acid nanofilm material embedded with E nanoparticles is prepared by heat-treating the product or the E-doped titanic acid nanofilm material prepared according to the third aspect.

The thermal stability of the titanic acid nanofilm will be improved due to the presence of the doped E-group elements, and the thickening and shrinkage of the film under heating will be hindered by the doped E-group elements. Therefore, the thickness of the titanic acid nanofilm does not change significantly (it maintains in a thin film state), by controlling the heat treatment temperature and time during the heat treatment process. While the doped E-group elements, which are mainly distributed in the titanic acid nanofilm in the form of atoms or atomic clusters, will transform into E nanoparticles embedded in the titanic acid nanofilm by elemental diffusion and aggregation. This kind of embedded E nanoparticles is different from the ordinary nanoparticles adsorbed through van der Waals force that is reported in other literatures (nanoparticles adsorbed through van der Waals force can move and detach from the substrate). This kind of embedded E nanoparticles ensure that the E nanoparticles can be tightly embedded within the titanic acid nanofilm (it cannot move or detach from the substrate). When all of the E-group elements, which are mainly distributed as atoms or atomic clusters, have been aggregated into E nanoparticles, it is difficult for them to continue to merge and grow due to the island-like distribution of the E nanoparticles, which cannot be connected by the spatial obstruction of the titanic acid nanofilm matrix. Therefor, the particle size of the E nanoparticles can be kept roughly unchanged during the subsequent heating process.

Furthermore, the temperature of the heat treatment is 350° C.˜650° C.;

Furthermore, the temperature of the heat treatment is 350° C.˜600° C.;

Furthermore, the temperature of the heat treatment is 350° C.˜550° C.;

The heat treatment temperature ensures that the doped E-group elements generates E nanoparticles embedded in the titanic acid nanofilm through elemental diffusion and aggregation, while maintaining the morphology of the titanic acid nanofilm matrix without significant changes, except for a slight thickening of the thickness.

Furthermore, when the E-group elements is present in the E-doped titanic acid nanofilm in the form of atoms or atomic clusters, due to the pinning effect of the atoms of the E-group elements, the phase transition thermal stability of the phase transition of the titanic acid nanofilm matrix can be increased by up to 200° C.; and the higher the E content is, the higher the phase transition thermal stability is. That is, compared with the monolithic titanic acid nanofilm matrix, the heat treatment temperature of the E-doped titanic acid nanofilm needs to be increased by up to 200° C. to achieve the same phase transition during the heating process;

For example, the monolithic titanic acid nanofilm without E-group elements undergoes a phase transition by heat-treating at 450° C. for 1 h, while the titanic acid nanofilm containing high value of E-group elements still does not undergo a significant phase transition within the film matrix by heat-treating at 600° C. for 0.5 h;

Furthermore, the time of the heat treatment is 5 min˜96 h;

As a preference, the time of the heat treatment is 10 min˜5 h;

When a low value of the temperature range is selected and the content of the E-group elements is high, a longer time is required for the precipitate of the E nanoparticles through element diffusion and aggregation; when a high value of the temperature range is selected and the content of the E-group elements is low, a shorter time is required for the precipitate of the E nanoparticles through element diffusion and aggregation;

Furthermore, the E nanoparticles have a size of 1.5 nm˜10 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜7.5 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜5 nm;

Furthermore, the E nanoparticles are present in the titanic acid nanofilm mainly by means of embeddedness;

The “embedding” refers to a formation mode of in situ generation, i.e., the E nanoparticles are aggregated, grown-up and formed in situ through the diffusion of the doping E-group elements; The embedded E nanoparticles are manifested as being partially or completely embedded in the titanic acid nanofilm matrix, which does not rely on external addition or external mixed methods to make it embedded.

Furthermore, the thickness of the titanic acid nanofilm after heat treatment is slightly greater than the thickness before heat treatment;

Furthermore, the titanic acid nanofilm embedded with E nanoparticles has a thickness of 0.3 nm˜10 nm; Furthermore, the titanic acid nanofilm embedded with E nanoparticles has a thickness of 0.3 nm˜5 nm;

Furthermore, the titanic acid nanofilm embedded with E nanoparticles has a thickness of 0.3 nm˜4 nm;

Furthermore, the titanic acid nanofilm embedded with E nanoparticles has a thickness of 0.3 nm˜2 nm;

Furthermore, in addition to a volume portion embedded in the titanic acid nanofilm, the E-nanoparticles have a bare volume portion that is not embedded in the film;

Since the embedded E nanoparticles are generated by diffusion and aggregation of E-group elements originally distributed in the titanic acid nanofilm, they can be embedded and distributed in the film, and since the film is sufficiently thin, some of the E nanoparticles may also be exposed outside the film;

Furthermore, the average area of the titanic acid nanofilm embedded with E nanoparticles is greater than 400 nm²; As a preference, the average area of the titanic acid nanofilm embedded with E nanoparticles is greater than 4000 nm²;

As a Furthermore preference, the average area of the titanic acid nanofilm embedded with E nanoparticles is greater than 16000 nm²;

Furthermore, the chemical composition of the titanic acid nanofilm material embedded with E nanoparticles includes E-group elements, Ti, H, O elements; wherein the molar ratio of E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%;

Furthermore, the E-group elements is mainly Ag; Furthermore, the E-group elements is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also contain other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds;

Furthermore, when not all of the E-group elements are Ag, the E-group elements comprise at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

In the fifth aspect, the present invention also relates to a method of preparing a TiO₂nanosheet powder embedded with E nanoparticles, wherein the TiO₂nanosheet powder is prepared by heat-treating the product or the titanic acid nanofilm material doped with E-group elements prepared according to the third aspect thereof, or by heat-treating the product or the titanic acid nanofilm material embedded with E nanoparticles prepared according to the fourth aspect thereof.

Furthermore, the time for the heat treatment is 1 min˜48 h;

As a preference, the time for the heat treatment is 10 min˜3 h;

Furthermore, the temperature range of the heat treatment is 600° C.˜1500° C.;

Furthermore, the temperature range of the heat treatment is 600° C.˜1000° C.;

Furthermore, the heat treatment process generates nano-TiO₂;

When a low value of the temperature range is selected, a longer time is required to convert the titanic acid nanofilm into TiO₂nano-sheets, and when a high value of the temperature range is selected, a shorter time is required to convert the titanic acid nanofilm into TiO₂nano-sheets;

Furthermore, during the heat treatment process, and when the material subjected to heat treatment is a titanic acid nanofilm material doped with E-group elements, the diffusion and aggregation of the doped E-group elements first occurs therein to generate E nanoparticles embedded in the titanic acid nanofilm. With the increase of heat treatment temperature and time, the titanic acid nanofilm will shrink in area, increase in thickness, and change from titanic acid nanofilm to TiO₂nano-powder. Since the E nanoparticles embedded in the titanic acid nanofilm are separated and isolated by the titanic acid nanofilm matrix, it is difficult for the E nanoparticles that have been completely generated to continue to merge with each other and grow up, and their sizes and morphologies will be in a stable state in the process of phase transformation and thickening. That is, after all of the E-group elements existing as atoms or atomic clusters in the matrix are transformed into E nanoparticles, there is no additional source of E-group elements, and the dispersedly distributed E nanoparticles that have already been generated can not grow up significantly with the increase of the heat treatment temperature and the prolongation of the heat treatment time;

During the heat treatment process, and when the material undergoing heat treatment is a titanic acid nanofilm material embedded with E nanoparticles, since the E nanoparticles embedded in the titanic acid nanofilms are separated and isolated by the titanic acid nanofilm matrix, in the process of the phase transformation and thickening of the titanic acid nanofilms, if all of the E-group elements in the titanic acid nanofilm matrix that are present in the form of atoms or atomic clusters have been transformed into E nanoparticles, there is no additional source of E-group elements, it is difficult for the generated dispersed E nanoparticles to continue to merge with each other and grow up, and their sizes and morphologies will be in a stable state, i.e., they can not grow up with the increase of the heat treatment temperature and the prolongation of the heat treatment time.

Furthermore, when the thickness of the generated TiO₂nanosheet does not exceed the outer diameter of the E nanoparticles, the E nanoparticles are partially embedded and distributed in the TiO₂nanosheet;

Furthermore, when the thickness of the generated TiO₂nanosheet exceeds the outer diameter of the E nanoparticles, the E nanoparticles are wholly or partially embedded and distributed in the TiO₂nanosheet;

Furthermore, the phase composition of the nano-TiO₂in the TiO₂nanosheet powder containing the E nanoparticles includes at least one of brookite-type nano-TiO₂, anatase-type nano-TiO₂, and rutile-type nano-TiO₂.

Furthermore, during the heat treatment process, in addition to the diffusion and aggregation of the doped E-group elements to generate the E nanoparticles embedded in the titanic acid nanofilms, the morphology of the titanic acid nanofilm matrix will further undergo a transformation from a film to a sheet with a significant increase in the thickness, and at the same time, a transformation from titanic acid to TiO₂will also occur.

Specifically, as the heat treatment temperature and the heat treatment time increase, the product of the heat treatment of the titanic acid nanofilms embedded with E nanoparticles undergoes a continuous transformation from “titanic acid nanofilms embedded with E nanoparticles”→“anatase-type TiO₂nanosheets embedded with E nanoparticles”→“rutile-type TiO₂nanosheets embedded with E nanoparticles”. Certain examples also do not exclude the appearance of brookite-type TiO₂sheets embedded with E nanoparticles.

During the transformation process, the coexistence of two crystalline TiO₂may occur in the products corresponding to certain heat treatment temperatures and times, such as the coexistence of “titanic acid nanofilms embedded with E nanoparticles” and “anatase-type TiO₂nanosheets embedded with E nanoparticles”, as well as the coexistence of “anatase-type TiO₂nanosheets embedded with E nanoparticles” and “rutile TiO₂nanosheets embedded with E nanoparticles”.

Furthermore, the TiO₂nanosheet embedded with E nanoparticles has a shape of a plate sheet;

Furthermore, the TiO₂nanosheet embedded with E nanoparticles has a thickness of 1.0 nm˜30 nm;

Furthermore, the TiO₂nanosheet embedded with E nanoparticles has a thickness of 1.0 nm˜20 nm;

Furthermore, the average area of the TiO₂nanosheets embedded with E nanoparticles is greater than 100 nm²;

Furthermore, the average area of the TiO₂nanosheet embedded with E nanoparticles is greater than 1000 nm²;

Furthermore, the average area of the TiO₂nanosheets embedded with E nanoparticles is greater than 4000 nm²;

Furthermore, the E nanoparticles have a size of 1.5 nm˜10 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜7.5 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜5 nm;

Furthermore, the E nanoparticles are present in the TiO₂nanosheets mainly by means of embeddedness;

Furthermore, the chemical composition of the TiO₂nanosheets embedded with E nanoparticles includes E-group elements, Ti, and O element; wherein the molar ratio of E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%; Furthermore, the E-group elements is mainly Ag; Furthermore, the E-group elements is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also contain other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds;

Furthermore, when not all of the E-group elements are Ag, the E-group elements comprise at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

In the sixth aspect, the present invention also relates to a method of preparing E-doped titanate nanotubes, comprising the following steps:

- sealing a solid substance with a alkaline solution in a closed vessel, wherein the solid substance is the product or the titanate nanofilm doped with E-group elements prepared according to the first aspect, or (and) the product or the titanic acid nanofilm doped with E-group elements prepared according to the third aspect, then the solid substance and the alkaline solution in the closed vessel were treated by a high pressure and a high temperature of T₂which is higher than that of the T_{f solution}; wherein the T_{f solution}is the boiling temperature of the alkali solution involved in the reaction at ambient pressure, and T_{f solution}<T₂; after a certain time of reaction, the temperature of the closed vessel is reduced and the pressure is restored to ambient pressure, and the final solid product is collected, i.e., the E-doped titanate nanotubes are obtained.

Furthermore, the alkaline solution includes at least one of NaOH, KOH, LiOH, RbOH, Ba(OH)₂, Ca(OH)₂, Sr(OH)₂solution;

Furthermore, the solvent in the alkaline solution includes water; as a preference, the solvent in the alkaline solution is water;

Furthermore, the concentration of alkali in the alkaline solution is 5.1˜25 mol/L;

As a preference, the concentration of alkali in the alkaline solution is 5.1˜15 mol/L;

As a preference, the concentration of alkali in the alkaline solution is 7˜15 mol/L;

As a furthermore preference, the concentration of alkali in the alkaline solution is 7˜12 mol/L;

As a furthermore preference, the concentration of alkali in the alkaline solution is 10˜15 mol/L;

Furthermore, the concentration of alkaline refers to the concentration of OH⁻ in the alkaline;

Furthermore, the alkali in the alkaline solution mixed with the solid substance containing the titanate nanofilm doped with E-group elements as described in the first aspect thereof or (and) the titanic acid nanofilm doped with E-group elements as described in the third aspect thereof is in an excess dose of alkali, and the volume of the alkaline solution is more than 5 times the volume of the solid substance;

Furthermore, the volume of the alkaline solution is more than 10 times the volume of the solid substance; Furthermore, the volume of the alkaline solution is more than 20 times the volume of the solid substance;

As a preferred example,

- the “solid substance containing a titanate nanofilm doped with E-group elements as described in the first aspect thereof or (and) a titanic acid nanofilm doped with E-group elements as described in the third aspect thereof and an alkaline solution” is the solid flocculent product containing E-group elements and the corresponding alkaline solution after the hydrogen generation and T-removal reaction as described in step 1 and 2 in the first aspect;
- i.e.: sealing a solid substance with a alkaline solution in a closed vessel, wherein the solid substance is the solid flocculent product containing E-group elements and the corresponding alkaline solution after the hydrogen generation and T-removal reaction as described in step 1 and 2 in the first aspect; then the solid substance and the alkaline solution in the closed vessel were treated by a high pressure and a high temperature of T₂which is higher than that of the T_{f solution}; wherein the T_{f solution}is the boiling temperature of the alkali solution involved in the reaction at ambient pressure, and T_{f solution}<T₂; after a certain time of reaction, the temperature of the closed vessel is reduced and the pressure is restored to ambient pressure, and the final solid product is collected, i.e., the E-doped titanate nanotubes are obtained.

This preferred solution does not require separation of the solid flocculent product containing

E-group elements and the corresponding alkaline solution, followed by mixing the solid flocculent product containing E-group elements with an alkali, nor does it require the alkaline solution to be cooled down and then warmed up (T₁<T₂), and the alkali concentration meets the requirements of the high temperature and high pressure reaction of this preferred solution. Therefore, this is the most economical and simple operation scheme.

Furthermore, during the high temperature and high pressure treatment, titanate film or (and) titanic acid film is converted to tubular titanate and T_{f solution}<T₂;

Furthermore, T₁≤T_{f solution}<T₂;

Furthermore, the reaction is carried out in a closed vessel above atmospheric pressure so that the temperature of the alkaline solution can be heated above its boiling point temperature at atmospheric pressure, T_{f solution}, thereby achieving the conversion of the titanate nanofilm doped with E-group elements or (and) the titanic acid nanofilm doped with E-group elements to tubular titanate at high temperature and pressure.

Furthermore, in the closed container, when the alkaline solution species and concentration are determined, a determined value of temperature must correspond to a determined value of pressure, i.e., the value of pressure is a function of the value of temperature; the higher the temperature, the higher the pressure.

Furthermore, T_{f solution}<T₂<300° C.;

Furthermore, T_{f solution}<T₂<250° C.;

Furthermore, T_{f solution}<T₂<200° C.;

Furthermore, T_{f solution}<120° C.<T₂<200° C.;

Furthermore, T_{f solution}<140° C.<T₂<200° C.;

Furthermore, T_{f solution}<150° C.<T₂<180° C.;

Furthermore, the T₂temperature autoclave treatment time is 0.1 h˜10 h; Furthermore, the T₂temperature autoclave treatment time is 0.1 h˜1 h; Furthermore, the T₂temperature autoclave treatment time is 0.1 h˜0.5 h; Furthermore preferably, the T₂temperature autoclave treatment time is 0.1 h˜0.2 h;

Since the product can also be obtained by continuing the holding time after the reaction equilibrium, the holding time can also be selected as a longer time value.

Furthermore, the E-doped titanate nanotubes have an outer diameter of 2 nm˜20 nm;

Furthermore, the E-doped titanate nanotubes have an outer diameter of 3 nm˜15 nm;

Furthermore, the average length of the E-doped titanate nanotubes is greater than 5 times its average outer diameter.

Furthermore, the E-doped titanate nanotubes are mainly low crystallinity titanates;

Furthermore, the cationic elements in the titanate nanotubes are derived from corresponding cationic elements in the alkali;

Furthermore, the chemical composition of the E-doped titanate nanotubes includes E-group elements, Ti, O, and the corresponding cationic element in the alkal; wherein the molar ratio of the

E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25; for example, when the alkali is NaOH, the corresponding cationic element in the alkali is Na, and the E-doped titanate nanotubes of the chemical composition includes E, T₁, O, and the element Na.

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the E-group elements is mainly distributed in the titanate nanotubes as atoms or atomic clusters;

Furthermore, when the E-group elements is mainly distributed among the titanate nanotubes in the form of atoms or atomic clusters, the titanate nanotubes can be viewed as a single-phase material. That is to say, the E-group elements are uniformly distributed in the titanate nanotubes as the titanate nanotubes constituent elements are distributed as atoms or atomic clusters, and the E-group elements do not nucleate and grow into the E nanoparticle phase other than the titanate phase. At this time, the as-prepared product can be understood as E-doped titanate nanotubes, or as titanate nanotubes with E-group elements solid dissolved, or as a completely new substance, such as titanate (silver) nanotubes;

Furthermore, the E-group elements is mainly distributed in the titanate nanotubes in a embedding form as atoms or atomic clusters; the key feature of the embedding distribution is that the E-group elements is mainly confined in the titanate nanotubes in the form of atoms or atomic clusters, and the atomic diffusion can only take place when a certain temperature is achieved; at the same time, due to the pinning effect of the E-group elements, it can greatly improve the thermal stability of the titanate nanotubes matrix. For a detailed introduction, please refer to the following text corresponding to it.

Furthermore, when the E-group elements is present in the E-doped titanate nanotubes in the form of atoms or atomic clusters, due to the pinning effect of the atoms of the E-group elements, the thermal stability of the phase transition of the titanate nanotubes matrix can be increased by up to 200° C.; and the higher the content of E is, the higher the thermal stability of the phase transition is. That is, compared with the monolithic titanate nanotubes matrix, the heat treatment temperature of the E-doped titanate nanotubes needs to be increased by up to 200° C. to achieve the same phase transition during the heating process;

This increase in the thermal stability of the phase transition further indicates that the E-group elements is doped in the titanate nanotubes matrix on an atomic or atomic cluster scale, rather than as an obvious E nanoparticle phase. If it present as an obvious E nanoparticle phase, and the titanate nanotubes matrix and the E nanoparticle phase are separate and independent phases, the phase transition thermal stability of the titanate nanotubes matrix can not be greatly affected by the presence of E nanoparticle phase.

Furthermore, the process of collecting the final solid product includes a drying process, i.e. to obtain E-doped titanate nanotubes in powder form.

Furthermore, the drying temperature is 50° C.˜350° C.;

Furthermore, the drying temperature is 50° C.˜300° C.;

Furthermore, the drying time is 1 min˜24 h;

Furthermore, the drying time is 5 min˜2 h;

Furthermore, the drying time is in a low value range when the drying temperature is in a high value range;

Furthermore, the drying time is in a high value range when the drying temperature is in a low value range;

Furthermore, when the drying temperature takes the low value of the range, the E-doped titanate nanotubes contain O-bound Ag atoms or Ag clusters;

As a preference, when the drying temperature is 50° C.˜180° C., the E-doped titanate nanotubes contain O-bound Ag atoms or Ag clusters; As a preference, when the drying temperature is 50° C.˜180° C., the E-doped titanate nanotubes contain O-bound Ag₂O clusters;

Furthermore, when the drying temperature takes the high value of the range, the E-group elements are mainly distributed in the titanate nanotubes in the form of atoms or atomic clusters;

As a preference, when the drying temperature is 181° C.˜350° C., the E-group elements are mainly distributed among the titanate nanotubes in the form of atoms or atomic clusters.

Therefore, the degree of bonding with Ag and O can be controlled by the control of the drying temperature and drying time.

Furthermore, when the drying temperature is lower than 350° C., the shape of the titanate nanotubes remains substantially unchanged and the E elements remain embedded and distributed in the titanate nanotubes as atoms or atomic clusters;

Furthermore, the atomic clusters containing E-group elements have a size of less than 1.5 nm;

Furthermore, the atomic clusters containing E-group elements have a size of less than 1 nm, and when the atomic clusters containing E-group elements are less than 1 nm, the size of such atomic clusters is not sufficient to form E-phase nanoparticles that are distinguishable at the phase interface and it is difficult to distinguish the atomic clusters containing E-group elements from the titanate nanotube matrix by means of observation, such as transmission electron microscopy (TEM); thus in this scale, it is uniformly distributed in the matrix.

Furthermore, the E-group elements is mainly distributed in the titanate nanotubes in the form of atoms;

Furthermore, the E-doped titanate nanotubes are mainly prepared by high-temperature and high-pressure treatment of the E-doped titanate nanofilm, so that when the high-temperature and high-pressure treatment is incomplete, the as-prepared product will also contain the E-doped titanate nanofilm;

Furthermore, the weight percentage content of the E-doped titanate nanotubes in the final product is higher than 50%;

Furthermore, the weight percentage content of the E-doped titanate nanotubes in the final product is higher than 90%;

Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%; Furthermore, the E-group elements is mainly Ag; Furthermore, the E-group elements is Ag; Furthermore, when not all of the E-group elements are Ag, the E-group elements also contain other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds;

Furthermore, when not all of the E-group elements are Ag, the E-group elements comprise at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

In the seventh aspect, the present invention also relates to a method of preparing titanate nanotubes embedded with E nanoparticles, wherein the titanate nanotubes embedded with E nanoparticles are prepared by heat-treating the final product or the titanate nanotubes doped with E-group elements prepared according to the sixth aspect.

Since the thermal stability of the titanate nanotubes is improved by the presence of the doped E-group elements, the titanate nanotubes can be kept virtually unchanged in morphology and phase composition by controlling the appropriate heat treatment temperature and time during the heat treatment process, The E-doped group element, which is mainly distributed in the titanate nanotubes in the form of atoms or atomic clusters, can transform into E nanoparticles embedded in the titanate nanotubes by elemental diffusion and aggregation. This kind of embedded E nanoparticles is different from the ordinary nanoparticles adsorbed through van der Waals force that is reported in other literatures (nanoparticles adsorbed through van der Waals force can move and detach from the substrate). This kind of embedded E nanoparticles ensure that the E nanoparticles can be tightly embedded within the titanate nanotubes (it cannot move or detach from the substrate). When all of the E-group elements, which are mainly distributed as atoms or atomic clusters, have been aggregated into E nanoparticles, it is difficult for them to continue to merge and grow due to the island-like distribution of the E nanoparticles, which cannot be connected by the spatial obstruction of the titanate nanotube matrix. Therefor, the particle size of the E nanoparticles can be kept roughly unchanged during the subsequent heating process.

Furthermore, when the E-group elements is present in the E-doped titanate nanotube in the form of atoms or atomic clusters, due to the pinning effect of the atoms of the E-group elements, the thermal stability of the phase transition of the titanate nanotube matrix can be increased by a maximum of 200° C.; and the higher the E content is, the higher the thermal stability of the phase transition is. That is, compared with the monolithic titanate nanotube matrix, the heat treatment temperature of the E-doped titanate nanotube needs to be increased by up to 200° C. to achieve the same phase transition during the heating process;

Furthermore, the temperature of the heat treatment is 350° C.˜650° C.;

Furthermore, the temperature of the heat treatment is 350° C.˜600° C.;

Furthermore, the temperature of the heat treatment is 350° C.˜550° C.;

Furthermore, the time of the heat treatment is 2 min˜96 h;

Furthermore, the time of the heat treatment is 5 min˜10 h;

As a preference, the time of the heat treatment is 10 min˜5 h;

Furthermore, the E nanoparticles have a size of 1.5 nm˜10 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜7.5 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜5 nm;

Furthermore, the E nanoparticles are mainly present in titanate nanotubes by means of embeddedness;

The “embedding” refers to a formation mode of in situ generation, i.e., the E nanoparticles are aggregated, grown-up and formed in situ through the diffusion of the doping E-group elements; The embedded E nanoparticles are manifested as being partially or completely embedded in titanate nanotube matrix, which does not rely on external addition or external mixed methods to make it embedded.

Furthermore, the titanate nanotubes embedded with E nanoparticles have an outer diameter of 2 nm˜20 nm; Furthermore, the titanate nanotubes embedded with E nanoparticles have an outer diameter of 3 nm˜15 nm;

Furthermore, the titanate nanotubes embedded with E nanoparticles have an average length greater than 5 times their average outer diameter;

Furthermore, the embedded E nanoparticles are embedded in a way that includes all of the nanoparticles embedded in the titanate nanotubes, or part of the E nanoparticles embedded in the titanate nanotubes, and also includes an exposed portion that is not embedded in the titanate nanotubes.

Furthermore, the main chemical composition of the titanate nanotubes embedded with E nanoparticles includes E-group elements, Ti, O, and the corresponding cationic element in the corresponding alkaline solution of the original preparation process, wherein the molar ratio of E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%;

Furthermore, the E-group elements is mainly Ag; Furthermore, the E-group elements is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also contain other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds;

Furthermore, when not all of the E-group elements are Ag, the E-group elements comprise at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

In the eighth aspect, the present invention also relates to a method of preparing titanic acid nanotubes doped with E-group elements, wherein the titanic acid nanotubes doped with E-group elements are obtained by reacting the final product or the titanate nanotubes doped with E-group elements prepared according to the sixth aspect with an acid solution and collecting the solid product.

Furthermore, the acid solution includes at least one of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, phosphoric acid, oxalic acid, picric acid, oleic acid, perchloric acid.

By reacting with the acid solution, the residual alkali adsorbed on the surface of the E-doped titanate nanotubes is first neutralized, and then ion exchange between the E-doped titanate nanotubes and the hydrogen ions in the acid solution occurs, and then the E-doped titanic acid nanotubes are obtained.

Since the titanic acid nanotubes have a slightly smaller specific surface area than the titanic acid nanofilm, the reaction can be carried out in an acid with a slightly higher concentration compared to the acid solution in the third aspects thereof;

Furthermore, the hydrogen ion concentration in the acid solution is 0.001 mol/L˜0.2 mol/L;

As a preference, the hydrogen ion concentration in the acid solution is 0.001 mol/L˜0.1 mol/L;

As a preference, the hydrogen ion concentration in the acid solution is 0.001 mol/L˜0.05 mol/L;

Furthermore, the specific step of reacting the E-doped titanate nanotube material with the acid solution is as follows: the E-doped titanate nanotube material is dispersed in water, and the acid solution is gradually added while stirring so that the pH of the mixed solution continuously decreases. Finally, the pH of the mixed solution is controlled to be in the range of 2˜5, and after 1 min˜5 h, followed by separation and drying then the E-doped titanic acid nanotube material was obtained. Since the titanate nanotubes are rolled up with a certain thickness, when the pH value is maintained between 2 and 4, corresponding to a concentration of hydrogen ions in the mixed solution is 0.0001 mol/L˜0.01 mol/L, it can be ensured that the residual alkali adsorbed on the surface of the E-doped titanate nanotube material is first neutralized during the whole process, and then the ion exchange between the cations in the E-doped titanate nanotube and hydrogen ions in the acid solution takes place, thereby the E-doped titanic acid nanotube material that has not reacted significantly with the acid solution is obtained.

Furthermore, the E-doped titanic acid nanotubes have an outer diameter of 2 nm˜20 nm;

Furthermore, the E-doped titanic acid nanotubes have an outer diameter of 3 nm˜15 nm;

Furthermore, the average length of the E-doped titanic acid nanotubes is greater than 5 times its average outer diameter;

Furthermore, the E-doped titanic acid nanotubes are mainly low crystallinity titanate;

Furthermore, the chemical composition of the E-doped titanic acid nanotubes includes E, Ti, O, H; wherein the molar ratio of the E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the E-group elements is mainly distributed in the titanic acid nanotubes as atoms or atomic clusters;

Furthermore, when the E-group elements is distributed mainly as atoms or atomic clusters in the titanic acid nanotubes, the titanic acid nanotubes can be viewed as a single phase material. That is, the E-group elements, and other titanic acid nanotube constituent elements such as Ti, H, O, is uniformly distributed in the titanic acid nanotubes as atoms or atomic clusters, and the E-group elements does not nucleate and grow into the E nanoparticle phase other than the titanic acid nanotubes. At this time, the as-prepared product can be understood as E-doped titanic acid nanotubes, or titanic acid nanotubes with E-group elements solid dissolved, or it can be considered as a new substance;

Furthermore, the E-group elements is mainly distributed in titanic acid nanotubes in a embedding form as atoms or atomic clusters; the key feature of the embedding distribution is that the E-group elements is mainly confined in the titanic acid nanotubes in the form of atoms or atomic clusters, and the atomic diffusion can only take place when a certain temperature is achieved; at the same time, due to the pinning effect of the E-group elements, it can greatly improve the thermal stability of the titanic acid nanotube matrix. For a detailed introduction, please refer to the following text corresponding to it.

Furthermore, when the E-group elements is present in the E-doped titanic acid nanotube in the form of atoms or atomic clusters, due to the pinning effect of the atoms of the E-group elements, the thermal stability of the phase transition of the titanic acid nanotube matrix can be increased by a maximum of 200° C.; and the higher the content of E is, the higher the thermal stability of the phase transition is. That is, compared with the monolithic titanic acid nanotube matrix, the heat treatment temperature of the E-doped titanic acid nanotubes needs to be increased by up to 200° C. to achieve the same phase transition during the heating process;

This increase in the thermal stability of the phase transition further indicates that the E-group elements is doped in the titanic acid nanotube matrix on an atomic or atomic cluster scale, rather than as an obvious E nanoparticle phase. If it present as an obvious E nanoparticle phase, and the titanic acid nanotube matrix and the E nanoparticle phase are separate and independent phases, the phase transition thermal stability of the titanic acid nanotube matrix can not be greatly affected by the presence of E nanoparticle phase.

Furthermore, the process of collecting the solid product includes a drying process;

Furthermore, the drying temperature is 50° C.˜350° C.;

Furthermore, the drying temperature is 50° C.˜300° C.;

Furthermore, the drying time is 1 min˜24 h;

Furthermore, the drying time is 5 min˜2 h;

Furthermore, the drying temperature is in a high value range when the drying time is in a low value range;

Furthermore, the drying time is in a high value range when the drying temperature is in a low value range;

Furthermore, when the drying temperature takes the low value of the range, the E-doped titanic acid nanotubes contain O-bound Ag atoms or Ag clusters;

As a preference, when the drying temperature is from 50° C.˜180° C., the E-doped titanic acid nanotubes contain O-bound Ag atoms or Ag clusters;

As a preference, when the drying temperature is 50° C.˜180° C., the E-doped titanic acid nanotubes contain O-bound Ag₂O clusters;

Furthermore, when the drying temperature takes the high value of the range, the E-group elements are mainly distributed in the titanic acid nanotubes in the form of atoms or atomic clusters;

As a preference, when the drying temperature is 181° C.˜350° C., the E-group elements is mainly distributed among the titanic acid nanotubes in the form of atoms or atomic clusters.

Therefore, the degree of bonding with Ag and O can be controlled by the control of the drying temperature and drying time.

Furthermore, when the drying temperature is lower than 350° C., the shape of the titanic acid nanotubes remains substantially unchanged and the E elements remain embedded and distributed in the titanic acid nanotubes as atoms or atomic clusters;

Furthermore, the atomic clusters containing E-group elements have a size of less than 1.5 nm;

Furthermore, the atomic clusters containing E-group elements have a size of less than 1 nm, and when the atomic clusters containing E-group elements are less than 1 nm, the size of such atomic clusters is insufficient to form E-phase nanoparticles that are distinguishable at the phase interface and it is difficult to distinguish the atomic clusters containing E-group elements from the titanic acid nanotube matrix by means of observation, such as transmission electron microscopy (TEM); thus in this scale, it is uniformly distributed in the matrix.

Furthermore, the E-group elements is mainly distributed as atoms in the titanic acid nanotubes;

Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%; Furthermore, the E-group elements is predominantly Ag; the E-group elements is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also contain other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds;

Furthermore, when not all of the E-group elements are Ag, the E-group elements comprise at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

In the ninth aspect, the present invention also relates to a method of preparing titanic acid nanotubes embedded with E nanoparticles, wherein the titanic acid nanotubes embedded with E nanoparticles are prepared by heat-treating the product or the titanic acid nanotubes doped with E-group elements prepared according to the eighth aspect.

The thermal stability of the titanic acid nanotubes will be improved due to the presence of the doped E-group elements, and the structural transformation of the titanic acid nanotubes under heating will be hindered by the doped E-group elements. In the heat treatment process, the titanic acid nanotubes can be kept basically unchanged in morphology and phase composition by controlling the appropriate heat treatment temperature and time during the heat treatment process, While the doped E-group elements, which are mainly distributed in the titanic acid nanotubes in the form of atoms or atomic clusters, will transform into E nanoparticles embedded in the titanic acid nanotubes by elemental diffusion and aggregation.

This kind of embedded E nanoparticles is different from the ordinary nanoparticles adsorbed through van der Waals force that is reported in other literatures (nanoparticles adsorbed through van der Waals force can move and detach from the substrate). This kind of embedded E nanoparticles ensure that the E nanoparticles can be tightly embedded within the titanic acid nanotubes (it cannot move or detach from the substrate). When all of the E-group elements, which are mainly distributed as atoms or atomic clusters, have been aggregated into E nanoparticles, it is difficult for them to continue to merge and grow due to the island-like distribution of the E nanoparticles, which cannot be connected by the spatial obstruction of the titanic acid nanotube matrix. Therefor, the particle size of the E nanoparticles can be kept roughly unchanged during the subsequent heating process.

Furthermore, the temperature of the heat treatment is 350° C.˜650° C.;

Furthermore, the temperature of the heat treatment is 350° C.˜600° C.;

Furthermore, the temperature of the heat treatment is 350° C.˜550° C.;

The heat treatment temperature ensures that the doped E-group elements transform into E nanoparticles embedded in the titanic acid nanotubes through elemental diffusion and aggregation, while maintaining the titanic acid nanotube matrix morphology without significant changes.

Furthermore, when the E-group elements is present in the E-doped titanic acid nanotube in the form of atoms or atomic clusters, due to the pinning effect of the atoms of the E-group elements, the thermal stability of the phase transition of the titanic acid nanotube matrix can be increased by up to 200° C.; and the higher the E content is, the higher the thermal stability of the phase transition is. That is, compared with the monolithic titanic acid nanotube matrix, the heat treatment temperature of the E-doped titanic acid nanotubes needs to be increased by up to 200° C. to achieve the same phase transition during the heating process;

Furthermore, the time of the heat treatment is 5 min˜96 h;

Furthermore, the time of the heat treatment is 5 min˜10 h;

As a preference, the time of the heat treatment is 10 min˜5 h;

Furthermore, the E nanoparticles have a size of 1.5 nm˜10 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜7.5 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜5 nm;

Furthermore, the E nanoparticles are mainly present in the titanic acid nanotubes by means of embeddedness;

The “embedding” refers to a formation mode of in situ generation, i.e., the E nanoparticles are aggregated, grown-up and formed in situ through the diffusion of the doping E-group elements; The embedded E nanoparticles are manifested as being partially or completely embedded in the titanic acid nanotube matrix, which does not rely on external addition or external mixed methods to make it embedded.

Furthermore, the titanic acid nanotubes embedded with E nanoparticles have an outer diameter of 2 nm˜20 nm;

Furthermore, the titanic acid nanotubes embedded with E nanoparticles have an outer diameter of 3 nm˜15 nm;

Furthermore, the titanic acid nanotubes embedded with E nanoparticles have an average length greater than 5 times their average outer diameter;

Furthermore, the embedded E nanoparticles are embedded in a way that includes all of the nanoparticles embedded in the titanic acid nanotubes, or part of the E nanoparticles embedded in the titanic acid nanotubes, and also includes an exposed portion that is not embedded in the titanic acid nanotubes.

Furthermore, the main chemical composition of the titanic acid nanotubes embedded with E nanoparticles includes E-group elements, Ti, H, and O, wherein the molar ratio of E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25;

Furthermore, the titanic acid nanotubes embedded with E nanoparticles have a chemical composition including an element of the E-group elements, Ti, H, and O; wherein the molar ratio of the element of the E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%; Furthermore, the E-group elements is mainly Ag; Furthermore, the E-group elements is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also contain other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds;

Furthermore, when not all of the E-group elements are Ag, the E-group elements comprise at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

In the tenth aspect, the present invention also relates to a method of preparing crystalline TiO₂nanotubes/rods embedded with E nanoparticles, wherein the crystalline TiO₂nanotubes/rods embedded with E nanoparticles are prepared by heat-treating the product or the titanic acid nanotubes doped with E-group elements prepared according to the eighth aspect, or by heat-treating the product or the titanic acid nanotubes embedded with E nanoparticles prepared according to the ninth aspect.

Furthermore, the time of the heat treatment is 1 min˜48 h;

As a preference, the time of the heat treatment is 10 min˜3 h;

Furthermore, the temperature of the heat treatment is 600° C.˜1500° C.;

Furthermore, the temperature of the heat treatment is 600° C.˜1000° C.;

Furthermore, the titanic acid nanotubes transform into crystalline TiO₂nanotubes/rods during the heat treatment;

When a low value of the temperature range is selected, a longer time is required to convert the titanic acid nanotubes into TiO₂nanotubes/rods, and when a high value of the temperature range is selected, a shorter time is required to convert the titanic acid nanotubes into TiO₂nanotubes/rods;

Furthermore, during the heat treatment process, and when the material subjected to heat treatment is an E-doped titanic acid nanotubes described in the eighth aspect, the diffusion and aggregation of the doped E-group elements first occurs therein to generate E nanoparticles embedded in the titanic acid nanotubes; and at this time, the state of the material is consistent with that of the titanic acid nanotubes embedded with E nanoparticles as described in the ninth aspect. As the heat treatment temperature and time increase, the titanic acid nanotubes transform into crystalline TiO₂nanotubes/rods. Since the E nanoparticles embedded in the titanic acid nanotubes or the crystalline TiO₂nanotubes/rods are separated and isolated by the titanic acid nanotube matrix or the crystalline TiO₂nanotube/rod matrix, it is difficult for the E nanoparticles that have been completely generated to continue to merge with each other and grow up, and their sizes and morphologies will be in a stable state in the process of phase transformation, and they will not be significantly changed with the elevation of the heat-treatment temperature and the prolongation of the heat-treatment time.

Furthermore, the crystalline TiO₂nanotubes/rods means that the shape of the crystalline TiO₂nanotubes/rods includes at least one of tubes and rods; when the inner diameter of the tubes is reduced to zero, it is the shape of the rods;

Furthermore, the crystalline TiO₂nanotubes/rods with embedded E nanoparticles have a phase composition including at least one of brookite TiO₂, anatase TiO₂, rutile TiO₂.

Specifically, with the increase of heat treatment temperature and time, the heat-treated product undergoes the successive transformation of “titanic acid nanotubes with embedded E nanoparticles”→“anatase TiO₂nanotubes/rods with embedded E nanoparticles”→“rutile TiO₂nanotubes/rods with embedded E nanoparticles”.

During the transformation process, two crystalline types may coexist in the as-prepared product corresponding to certain heat treatment temperatures and times, such as the coexistence of “titanic acid nanotubes with embedded E nanoparticles” and “anatase TiO₂nanotubes/rods with embedded E nanoparticles”, and the coexistence of “anatase TiO₂nanotubes/rods with embedded E nanoparticles” and “rutile TiO₂nanotubes/rods with embedded E nanoparticles”.

Furthermore, the E nanoparticles have a size of 1.5 nm˜10 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜7.5 nm;

Furthermore, the E nanoparticles have a size of 1.5 nm˜5 nm;

Furthermore, the E nanoparticles are predominantly present in the crystalline TiO₂nanotubes/rods by means of embeddedness;

Furthermore, the crystalline TiO₂nanotubes/rods embedded with E nanoparticles have an outer diameter of 2 nm˜25 nm;

Furthermore, the crystalline TiO₂nanotubes/rods embedded with E nanoparticles have an outer diameter of 3 nm˜20 nm;

Furthermore, the crystalline TiO₂nanotubes/rods embedded with E nanoparticles have an average length greater than three times of their average outer diameter;

Furthermore, the embedded E nanoparticles are embedded in a form that includes all of the nanoparticles embedded in the TiO₂nanotubes/rods, or part of the nanoparticles embedded in the TiO₂nanotubes/rods, and also includes a exposed portion of the E nanoparticles that is not embedded in the TiO₂nanotubes/rods.

Furthermore, the chemical composition of the crystalline TiO₂nanotubes/rods with embedded E nanoparticles includes E-group elements, T₁, O; wherein the molar ratio of E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%; Furthermore, the E-group elements is mainly Ag; Furthermore, the E-group elements is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also contain other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds;

Furthermore, when not all of the E-group elements are Ag, the E-group elements comprise at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

In the eleventh aspect, the present invention also relates to a titanate nanofilm material doped with E-group elements, which is prepared by a method of preparing a titanate nanofilm material doped with E-group elements prepared according the first aspect.

In the twelfth aspect, the present invention also relates to a titanate nanofilm material embedded with E nanoparticles, which is prepared by a method of preparing a titanate nanofilm material embedded with E nanoparticles prepared according to the second aspect.

In the thirteenth aspect, the present invention also relates to a titanic acid nanofilm material doped with E-group elements, which is prepared by a method of preparing a titanic acid nanofilm material doped with E-group elements prepared according to the third aspects.

In the fourteenth aspect, the present invention also relates to a titanic acid nanofilm material embedded with E nanoparticles, which is prepared by a method of preparing a titanic acid nanofilm material embedded with E nanoparticles prepared according to the fourth aspect.

In the fifteenth aspect, the present invention also relates to a TiO₂nanosheet powder embedded with E nanoparticles, which is prepared by a method of preparing a TiO₂nanosheet powder embedded with E nanoparticles prepared according to the fifth aspect.

In the sixteenth aspect, the present invention also relates to a titanate nanotube doped with E-group elements, which is prepared by a method of preparing a titanate nanotube doped with E-group elements prepared according to the sixth aspect.

In the seventeenth aspect, the present invention also relates to a titanate nanotube embedded with E nanoparticles, which is prepared by a method of preparing a titanate nanotube embedded with E nanoparticles prepared according to the seventh aspect.

In the eighteenth aspect, the present invention also relates to a titanic acid nanotube doped with E-group elements, which is prepared by a method of preparing a titanic acid nanotube doped with E-group elements prepared according to eighth aspect.

In the nineteenth aspect, the present invention also relates to a titanic acid nanotube embedded with E nanoparticles, which is prepared by a method of preparing a titanic acid nanotube embedded with E nanoparticles prepared according to the ninth aspect.

In the twenty aspects, the present invention also relates to a crystalline TiO₂nanotube/rod embedded with E nanoparticles, which is prepared by a method of preparing a crystalline TiO₂nanotube/rod embedded with E nanoparticles prepared according to the tenth aspect.

In the twenty-first aspect, the present invention also relates to another method of preparing titanate nanotubes doped with E-group elements, which are prepared by the following steps:

- step 1), providing an initial alloy comprising T-type elements, T₁and E-group elements; wherein the T-type elements comprise at least one of Al and Zn; and the phase composition of the initial alloy comprises a T-Ti intermetallic compound with solid dissolved E-group elements; wherein the atomic percentage content of Ag in the E-group elements is 50%˜100%, and the molar ratio of E-group elements solid dissolved in the T-Ti intermetallic compound to T₁in the initial alloy is 0<C_E/C_Ti≤0.25;
- step 2), sealing the initial alloy with the alkaline solution in a closed vessel, and subsequently heating the closed reaction system to the temperature of T₂and holding it for a certain period of time; wherein 100° C.<T_{f solution}<T₂; T_{f solution}is the boiling point temperature of the alkaline solution involved in the reaction at ambient pressure, and the pressure in the reaction vessel at the temperature of T₂is higher than the ambient pressure;
- step 3), lowering the temperature of the closed vessel and restoring the pressure to ambient pressure, and collecting the final solid product, i.e., obtaining titanate nanotubes doped with E-group elements.

The step 1), as well as the detailed description of step 1), are identical to step 1 and its detailed description described in the first aspect (a method for the preparation of nano-titanate thin-film materials doped with elements of group E) (see the step 1 described in the first aspect above);

In the step 2),

Furthermore, the initial alloy and the alkaline solution are sealed in a closed vessel at room temperature and pressure, and the temperature of the closed reaction system is subsequently heated to a high temperature of T₂and held for a certain period of time; wherein 100° C.<T_{f solution}<T₂;

Furthermore, the alkaline solution includes at least one of NaOH, KOH, LiOH, RbOH, Ba(OH)₂, Ca(OH)₂, Sr(OH)₂solution;

Furthermore, the solvent in the alkaline solution includes water; as a preference, the solvent in the alkaline solution is water; Furthermore, the concentration of alkali in the alkaline solution is 5.1˜25 mol/L;

As a preference, the concentration of alkali in the alkaline solution is 5.1˜15 mol/L;

As a preference, the concentration of alkali in the alkaline solution is 7˜15 mol/L; as a Furthermore preference, the concentration of alkali in the alkaline solution is 7˜12 mol/L;

As a Furthermore preference, the concentration of alkali in the alkaline solution is 10˜15 mol/L;

Furthermore, the concentration of alkaline refers to the concentration of OH— in the alkaline;

Furthermore, the alkali in the alkaline solution reacting with the initial alloy is an overdose, and the volume of the alkaline solution is more than 5 times the volume of the initial alloy, so that the reaction can be made to proceed all the time at a higher alkali concentration;

Furthermore, the volume of the alkaline solution is more than 10 times the volume of the initial alloy;

Furthermore, the volume of the alkaline solution is more than 20 times the volume of the initial alloy;

Furthermore, the temperature at which the initial alloy reacts with the alkaline solution is the temperature of the alkaline solution;

It can be understood that the reaction between the initial alloy and the alkaline solution is very slow in the preparation and beginning stages of the reaction at room temperature and atmospheric pressure, and that after the initial alloy and the alkaline solution are sealed in a closed container, the hydrogen generated by the reaction between the T-type elements in the initial alloy and the alkaline solution is also sealed in the closed container, which causes the pressure of the closed container to be elevated.

Furthermore, the closed reaction system includes, an initial alloy, an alkaline solution, and a closed container; the temperature of the closed reaction system is the temperature corresponding to the initial alloy, the alkaline solution, and the closed container;

Furthermore, the temperature of the initial alloy and the alkaline solution in the closed container is heated to the T₂temperature at a heating rate of greater than 10° C./min from room temperature;

Furthermore, the time for heating the temperature of the initial alloy and the alkaline solution in the closed container from room temperature to the T₂temperature is less than 30 min;

Furthermore, 100° C.<T_{f solution}<T₂<300° C.;

Furthermore, 100° C.<T_{f solution}<T₂<250° C.;

Furthermore, 100° C.<T_{f solution}<T₂<200° C.;

Furthermore, 100° C.<T_{f solution}<120° C.<T₂<200° C.;

Furthermore, 100° C.<T_{f solution}<140° C.<T₂<200° C.;

Furthermore, 100° C.<T_{f solution}<150° C.<T₂<180° C.;

Furthermore, the holding time of the closed reaction system at the T₂temperature is 0.1 h h; preferably 0.1 h˜2 h, preferably 0.1 h˜1 h, preferably 0.1 h˜0.5 h, further preferably 0.2 h˜0.4 h;

Since the product can also be obtained by continuing the holding time after the reaction has equilibrated, the holding time can also be selected as a longer time value.

Furthermore, the initial alloy in the closed vessel and the alkaline solution undergoes a hydrogen generation and T-removal reaction in the heating stage from room temperature to T₂temperature, which mainly generates nanoporous titanate intermediate products doped with E-group elements;

Furthermore, the conversion of the nanoporous titanate intermediate products doped with E-group elements to E-doped titanate nanotubes occurs during the holding stage at T₂temperature of the closed reaction system;

Furthermore, the pressure of the closed reaction system is higher than the atmospheric pressure;

Furthermore, the pressure of the closed reaction system is a combination of the pressure of the solution of the closed system at the temperature of T₂and the pressure of the hydrogen produced by the hydrogen evolution reaction at the temperature of T₂;

It can be understood that, because of the presence of the pressure of the generated hydrogen gas, the pressure of the closed reaction system is higher than the pressure corresponding to the simple closed system solution at the temperature of T₂; such a high-pressure environment creates conditions for the transformation of the nanoporous titanate intermediate product doped with E-group elements to the E-doped titanate nanotubes;

In the step 3).

Furthermore, the E-doped titanate nanotubes have an outer diameter of 3 nm˜25 nm;

Furthermore, the E-doped titanate nanotubes have an outer diameter of 3 nm˜20 nm;

Furthermore, the E-doped titanate nanotubes have an outer diameter of 4 nm 15 nm;

Furthermore, the average length of the E-doped titanate nanotubes is greater than 5 times its average outer diameter.

Furthermore, the E-doped titanate nanotubes are mainly low crystallinity titanates;

Furthermore, the cationic elements in the titanate nanotubes are derived from corresponding cationic elements in the alkali;

Furthermore, the chemical composition of the E-doped titanate nanotubes includes E, T₁, O, and the corresponding cationic element in the alkali; wherein the molar ratio of the E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25; for example, when the alkali is NaOH, the corresponding cationic element in the alkali is Na, and then the chemical composition of the E-doped titanate nanotubes contains E, Ti, O, and the element Na.

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the E-group elements is mainly distributed among the titanate nanotubes as atoms or atomic clusters; Furthermore, when the E-group elements is mainly distributed among the titanate nanotubes in the form of atoms or atomic clusters, the titanate nanotubes can be viewed as a single-phase material. That is to say, like other constituent elements in the titanate nanotubes, the E-group elements are uniformly distributed in the titanate nanotubes as atoms or atomic clusters, and the E-group elements do not nucleate and grow into the E nanoparticle phase other than the titanate phase. At this time, the as-prepared product can be understood as E-doped titanate nanotubes, or as titanate nanotubes with E-group elements solid dissolved, or as a completely new substance, such as titanate (silver) nanotubes;

Furthermore, the E-group elements is mainly distributed in titanate nanotubes in a embedding form as atoms or atomic clusters; the key feature of the embedding distribution is that the E-group elements is mainly confined in the titanate nanotubes in the form of atoms or atomic clusters, and the atomic diffusion can only take place when a certain temperature is achieved; at the same time, due to the pinning effect of the E-group elements, it can greatly improve the thermal stability of the titanate nanotubes.

Furthermore, the collection the final solid product in the step 3 of includes the drying of the final solid product, i.e., obtaining powdered E-doped titanate nanotubes.

Furthermore, the drying temperature is 50° C.˜350° C.;

Furthermore, the drying temperature is 50° C.˜300° C.;

Furthermore, the drying temperature is 50° C.˜250° C.;

Furthermore, the drying time is 1 min˜24 h;

Furthermore, the drying time is 5 min˜2 h;

Furthermore, the drying time may be in a low value range when the drying temperature is in a high value range;

Furthermore, when the drying temperature is in a low value range, the drying time is in a high value range;

Furthermore, when the drying temperature takes the low value of the range, the E-doped titanate nanotubes contain O-bound Ag atoms or Ag clusters;

As a preference, when the drying temperature is 50° C.˜180° C., the E-doped titanate nanotubes contain O-bound Ag atoms or Ag clusters;

As a preference, when the drying temperature is 50° C.˜180° C., the E-doped titanate nanotubes contain O-bound Ag₂O clusters;

Furthermore, when the drying temperature takes the high value of the range, the E-group elements are mainly distributed in the titanate nanotubes in the form of atoms or atomic clusters;

As a preference, when the drying temperature is 181° C.˜350° C., the E-group elements are mainly distributed among the titanate nanotubes in the form of atoms or atomic clusters.

Therefore, the degree of bonding with Ag and O can be controlled by the control of the drying temperature and drying time.

Furthermore, the atomic clusters containing E-group elements have a size of less than 1.5 nm;

Furthermore, the atomic clusters containing E-group elements have a size of less than 1 nm, and when the atomic clusters containing E-group elements are less than 1 nm, the size of such atomic clusters is not sufficient to form E-phase nanoparticles that are distinguishable at the phase interface and it is difficult to distinguish the atomic clusters containing E-group elements from the titanate nanotube matrix by means of observation, such as transmission electron microscopy (TEM); thus in this scale, it is uniformly distributed in the matrix.

Furthermore, the E-group elements is mainly distributed in the titanate nanotubes in the form of atoms;

The conversion process from the E-doped intermediate product to the E-doped titanate nanotubes also undergoes the formation of E-doped titanate nonofilms, so that when the high-temperature and high-pressure treatment is incomplete, the as-prepared product in step 3 will also contain the E-doped titanate nanofilms;

Furthermore, the weight percentage content of the E-doped titanate nanotubes in the final product is higher than 50%;

Furthermore, the weight percentage content of the E-doped titanate nanotubes in the final product is higher than 90%; Furthermore, the atomic percentage content of Ag in the E-group elements is 50%˜100%;

Furthermore, the E-group elements is mainly Ag; Furthermore, the E-group elements is Ag;

Furthermore, when not all of the E-group elements are Ag, the E-group elements also contain other elements capable of being solid dissolved in Ag or T-Ti intermetallic compounds;

Furthermore, when not all of the E-group elements are Ag, the E-group elements comprise at least one of Au, Cu, Pt, Pd, Ru, Rh, Os, Ir.

In the twenty-second aspect, the present invention also relates to a method of preparing a titanic acid nanotube doped with E-group elements, wherein the titanic acid nanotube doped with E-group elements is obtained by reacting the final product or the titanate nanotubes doped with E-group elements prepared according to the twenty-first aspect with an acid solution and collecting the solid product.

Furthermore, the acid solution includes at least one of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, phosphoric acid, oxalic acid, picric acid, oleic acid, perchloric acid.

Furthermore, the hydrogen ion concentration in the acid solution is 0.001 mol/L˜0.2 mol/L;

As a preference, the hydrogen ion concentration in the acid solution is 0.001 mol/L˜0.1 mol/L;

As a preference, the hydrogen ion concentration in the acid solution is 0.001 mol/L˜0.05 mol/L;

Furthermore, the E-doped titanic acid nanotubes have an outer diameter of 3 nm˜25 nm;

Furthermore, the E-doped titanic acid nanotubes have an outer diameter of 3 nm˜20 nm;

Furthermore, the E-doped titanic acid nanotubes have an outer diameter of 4 nm˜15 nm;

Furthermore, the average length of the E-doped titanic acid nanotubes is greater than 5 times its average outer diameter;

Furthermore, the E-doped titanic acid nanotubes are mainly low crystallinity titanate;

Furthermore, the chemical composition of the E-doped titanic acid nanotubes includes E, Ti, O, H; wherein the molar ratio of the E-group elements to Ti satisfies 0<C_E/C_Ti≤0.25;

Furthermore, 0<C_E/C_Ti≤0.10;

Furthermore, the E-group elements is mainly distributed in the titanic acid nanotubes as atoms or atomic clusters;

The key feature of the embedding distribution is that the E-group elements is mainly confined in the titanic acid nanotubes in the form of atoms or atomic clusters, and the atomic diffusion can only take place when a certain temperature is achieved; at the same time, due to the pinning effect of the E-group elements, it can greatly improve the thermal stability of the titanic acid nanotubes.