Patent Application
20250125380
This application claims priority to Korean Patent Application No. 10-2023-0136656 filed Oct. 13, 2023, the disclosure of which is hereby incorporated by reference in its entirety.
Embodiments of the present disclosure relate to a catalyst electrode, a method for manufacturing the catalyst electrode, and a membrane electrode assembly.
Hydrogen energy is clean energy and is attracting attention as one of the promising forms of alternative energy to solve energy problems in the long term. Among hydrogen production methods, the water electrolysis method, which uses electrical energy to separate water into hydrogen and oxygen and which does not emit carbon dioxide, is receiving much attention because it is eco-friendly, and is expected to greatly contribute to the achievement of carbon neutrality.
Meanwhile, water electrolysis reactions include the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), wherein the OER occurs at the oxygen evolution electrode and the HER occurs at the hydrogen evolution electrode. The OER and the HET are shown in Formula 1 below.
Oxygen evolution reaction:2H2O→4H++O2+4e−
Hydrogen evolution reaction:4H++4e−→2H2
Overall reaction: 2H2O→2H2+O2 [Formula 1]
In particular, in the water electrolysis reaction, an overpotential higher than the theoretical OER voltage occurs due to a slower reaction rate of the OER than that of the HER, so in order to improve the performance of a water electrolysis system, it is necessary to develop a high-efficiency catalyst lowering the overpotential of the OER which requires a high overpotential.
Embodiments of the present disclosure may provide a catalyst electrode with improved OER performance, a method for manufacturing the catalyst electrode, and a membrane electrode assembly.
A catalyst electrode according to an embodiment of the present disclosure comprises a metal layer; and a catalyst layer formed on the metal layer, wherein the catalyst layer comprises silver and iridium.
In one embodiment, the catalyst electrode contains iridium in the catalyst layer at a loading amount ranging from 0.02 mg/cm2 to 0.8 mg/cm2.
In one embodiment, at least a part of the silver and iridium comprised in the catalyst layer may be chemically bonded with each other.
In one embodiment, the metal layer may comprise one or more selected from the group consisting of a metal mesh, metal foam, metal foil, metal felt, and metal fiber.
In one embodiment, the metal layer may comprise one or more metals or metal alloy selected from the group consisting of titanium, nickel, and stainless steel.
In one embodiment, the catalyst layer may comprise: a first layer comprising the silver and in contact with the metal layer; and a second layer comprising the iridium and formed on the first layer.
In one embodiment, at least a part of the silver comprised in the first layer is chemically bonded with a metal of the metal layer.
In one embodiment, the catalyst layer may not comprise a binder.
A method for manufacturing a catalyst electrode according to an embodiment of the present disclosure comprises a step of coating a metal substrate with silver and iridium.
In one embodiment, the step of coating a metal substrate with silver and iridium may comprise: a step of forming a first layer comprising silver on the metal substrate by inputting the metal substrate to a silver precursor solution comprising a silver ion; and a step of forming a second layer comprising iridium on the first layer by inputting the metal substrate on which the first layer is formed to an iridium precursor solution comprising an iridium ion.
In one embodiment, the step of forming a first layer may comprise a step of heat-treating the substrate coated with the first layer.
In one embodiment, the step of heat-treating the substrate coated with the first layer is carried out at a temperature of 100° C. to 900° C. for 10 minutes to 10 hours.
In one embodiment, the step of forming a second layer may comprise a step of heat-treating the substrate coated with the second layer.
In one embodiment, the step of heat-treating the substrate coated with the second layer is carried out at a temperature of 100° C. to 900° C. for 10 minutes to 10 hours.
In one embodiment, the method for manufacturing a catalyst electrode may further comprise a step of acid-treating the metal substrate before the step of coating a metal substrate with silver and iridium.
In one embodiment, the silver precursor solution contains a silver precursor of one or more selected from the group consisting of silver nitrate, silver acetate, silver sulfate, silver perchlorate, silver acetylacetonate, and silver methanesulfonate; and/or the iridium precursor solution contains an iridium precursor of one or more selected from the group consisting of iridium chloride, an iridium chloride hydrate, iridium bromide, iridium acetylacetonate, hexachloroiridic acid, sodium hexachloroiridate, and potassium hexachloroiridate, preferably iridium chloride hydrate.
A membrane electrode assembly according an embodiment of the present disclosure comprises: an electrolyte membrane; an anode positioned on one surface of the electrolyte membrane; and a cathode positioned on the other surface of the electrolyte membrane, wherein the anode comprises: a metal layer; and a catalyst layer formed on the metal layer and comprising silver and iridium.
The present disclosure further provides a use of the catalyst electrode for being included in a water electrolysis device or in a fuel cell.
According to the present disclosure, a catalyst electrode with improved OER performance, a method for manufacturing the catalyst electrode, and a membrane electrode assembly can be provided.
The structural or functional descriptions of embodiments disclosed in the present specification or application are merely illustrated for the purpose of explaining embodiments according to the technical principle of the present invention, and embodiments according to the technical principle of the present invention may be implemented in various forms in addition to the embodiments disclosed in the specification of application. In addition, the technical principle of the present invention is not construed as being limited to the embodiments described in the present specification or application.
Hereinafter, the present invention will be described in detail with reference to the accompanying drawing. However, those skilled in the art will appreciate that such embodiments described with reference to the accompanying drawing are provided to further understand the spirit of the present invention and do not limit subject matters to be protected as disclosed in the detailed description and appended claims.
Furthermore, throughout the disclosure, unless otherwise particularly stated, the word “comprise”, “include”, “contain”, or “have” does not mean the exclusion of any other constituent element, but means further inclusion of other constituent elements, and elements, materials, or processes which are not further listed are not excluded.
Unless the context clearly indicates otherwise, the singular forms of the terms used in the present specification may be interpreted as including the plural forms. As used herein, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly states otherwise.
The numerical range used in the present disclosure comprises all values within the range comprising the lower limit and the upper limit, increments logically derived in a form and spanning in a defined range, all double limited values, and all possible combinations of the upper limit and the lower limit in the numerical range defined in different forms. As an example, when it is defined that a content of a composition is 10% to 80% or 20% to 50%, it should be interpreted that a numerical range of 10% to 50% or 50% to 80% is also described in the specification of the present disclosure. Unless otherwise defined in the present disclosure, values which may be outside a numerical range due to experimental error or rounding off of a value are also comprised in the defined numerical range.
For the purposes of this disclosure, unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, dimensions, physical characteristics, and so forth used in the disclosure are to be understood as being modified in all instances by the term “about.” Hereinafter, unless otherwise particularly defined in the present disclosure, “about” may be considered as a value within 30%, 25%, 20%, 15%, 10%, 5%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of a stated value. Unless indicated to the contrary, the numerical parameters set forth in this disclosure are approximations that can vary depending upon the desired properties sought to be obtained by the present invention.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
In one aspect of the present disclosure, provided is a catalyst electrode comprising a metal layer; and a catalyst layer formed on the metal layer, wherein the catalyst layer comprises sliver and iridium.
Referring to
The metal layer 10 may function as a metal substrate on which a catalyst metal is deposited, and in one embodiment, the metal of the metal layer 10 may comprise one or more selected from the group consisting of a metal mesh, metal foam, metal foil, metal felt, and metal fiber, which respectively is made of an appropriate metal or metal alloy. In addition, in one embodiment, the metal of the metal layer 10 may comprise one or more metals or metal alloy selected from the group consisting of titanium, nickel, and stainless steel. For example, the metal layer 10 may comprise a titanium mesh, but is not limited thereto.
A catalyst layer 20 is formed on a metal layer 10 and comprises silver and iridium. The catalyst layer 20 may include silver and iridium in one layer, or the catalyst layer 20 may include silver and iridium in separate layers, respectively, as further described later. In an embodiment, the metal layer 10 may be first coated with silver and then coated with iridium. In one embodiment, the catalyst layer 20 may comprise a first layer comprising silver and in contact with the metal layer 10; and a second layer comprising iridium and formed on the first layer. In one embodiment, at least a part of silver comprised in the first layer may be chemically boded to the metal of the metal layer 10, and accordingly, electron transfer performance and durability of the catalyst electrode 100 may be improved. The chemical bond between the silver and the metal of the metal layer may be a metallic bond.
In an embodiment, at least a part of silver and iridium comprised in the catalyst layer 20 may be chemically bonded to each other. The chemical bond between the silver and the iridium may be a metallic bond. In other words, as at least a part of silver and iridium comprised in the catalyst layer 20 is chemically bonded to each other, the electronic structure of at least a part of the silver and iridium comprised in the catalyst layer 20 may be changed. As the electronic structure of at least a part of the silver and iridium comprised in the catalyst layer 20 is changed, in particular, as the electronic structure of at least a part of the iridium comprised in the catalyst layer 20 is changed, the activity of the catalyst electrode 100 for oxygen evolution reaction (OER) may be improved, and as a result, the OER performance of the catalyst electrode 100 may be improved.
In an embodiment, the catalyst layer 20 may not comprise a binder. The metal layer 10 may be directly coated with silver and iridium, and a chemical bond may be formed between a metal of the metal layer 10 and the catalyst layer 20, such that the catalyst layer 20 may be formed on the metal layer 10 without using a separate binder.
The commonly used Nafion binder is a PFAS (Per- and polyfluoroalkyl substances), which can cause environmental issues, and there is a problem of reduced activity and reduced durability due to degradation of the Nation binder during the electrode reaction. Also, the catalyst layer 20 can be directly deposited on the current collector (metal layer 10) without the use of a binder, which increases the chemical bonding between the current collector (metal layer 10) and the catalyst layer 20, thereby improving electron-transferability and durability.
A catalyst electrode 100 according to an embodiment of the present disclosure may have an oxygen evolution performance equal to or even better than that of a conventional noble metal catalyst electrode, with only a small metal loading amount as compared to a conventionally used noble metal catalyst electrode.
A catalyst electrode 100 according to an embodiment of the present disclosure may be comprised in a water electrolysis device or may be comprised in a fuel cell, but the use of a catalyst electrode 100 is not limited thereto.
In another aspect of the present disclosure, provided is a method for manufacturing a catalyst electrode 100, comprising a step of coating a metal substrate 10 with silver and iridium.
A method for manufacturing a catalyst electrode 100 according to another embodiment of the present disclosure comprises a step of coating a metal substrate 10 with silver and iridium. In addition, the method for manufacturing a catalyst electrode according to another embodiment of the present disclosure may further comprise a step of acid-treating the metal substrate 10 before the step of coating the metal substrate 10 with silver and iridium. The metal substrate 10 may be a feature that is identical to the above-described metal layer 10, and accordingly, in an embodiment, the metal layer 10 may comprise one or more selected from the group consisting of a metal mesh, metal foam, metal foil, metal felt, and metal fiber, and in one embodiment, the metal layer may comprise one or more metals or metal alloy selected from the group consisting of titanium, nickel, and stainless steel.
Referring to
The S110 operation may be performed by inputting a metal substrate 10 to a silver precursor solution 200 comprising a silver ion (
The S110 operation may further comprise heat-treating the metal substrate 10 coated with the first layer 21 comprising silver. The heat-treating step may be performed at a temperature ranging from 100° C. to 900° C. for 10 minutes to 10 hours. Accordingly, the silver in the first layer 21 coated on the metal substrate 10 may have a stable metal phase, and impurities on the metal substrate 10 may be removed.
The S120 operation may be performed by adding the metal substrate 10 on which the first layer 21 is formed to an iridium precursor solution 300 comprising an iridium ion (
The S120 operation may further comprise heat-treating the substrate coated with the second layer 22 comprising iridium. The heat-treating step may be performed at a temperature ranging from 100° C. to 900° C. for 10 minutes to 10 hours. Accordingly, the iridium in the second layer 22 coated on the first layer 21 may have a stable metal phase.
Accordingly, as shown in
In another aspect of the present disclosure, provided is a membrane electrode assembly comprising an electrolyte membrane; an anode positioned on one surface of the electrolyte membrane; and a cathode positioned on the other surface of the electrolyte membrane, wherein the anode comprises: a metal layer; and a catalyst layer formed on the metal layer and comprising silver and iridium.
A membrane electrode assembly provided in another aspect of the present disclosure may comprise the above-described catalyst electrode 100 as an anode. In other words, the anode may comprise a metal layer 10; and a catalyst layer 20 formed on the metal layer 10 and comprising silver and iridium.
In addition, a membrane electrode assembly provided in another aspect of the present disclosure may comprise a cathode comprising a cathode catalyst, and the cathode catalyst may be a material commonly used in the art. For example, as a cathode catalyst, one single substance or a mixture of two or more substances selected the group consisting of platinum, ruthenium, iridium, osmium, palladium, platinum-ruthenium alloys, platinum-osmium alloys, platinum-palladium alloys, and oxides thereof may be used, but is not limited thereto.
In addition, a membrane electrode assembly provided in another aspect of the present disclosure may comprise an electrolyte membrane disposed between the anode and the cathode. For example, an electrolyte membrane may be a polymer electrolyte membrane comprising a fluorine-based polymer or a hydrocarbon-based polymer, but is not limited thereto.
A membrane electrode assembly provided in another aspect of the present disclosure may be comprised in a water electrolysis device or a fuel cell.
Hereinafter, a catalyst electrode, a method for manufacturing catalyst electrode and a membrane electrode assembly according to the present disclosure will be described in more detail based on examples and comparative examples. However, the following examples and comparative examples are only examples to describe the present disclosure in more detail, and the present disclosure is not limited by the following examples and comparative examples.
Silver nitrate (Sigma) was added to a mixed solution of distilled water/ethanol (volume ratio 1:1), and sonicated and stirred until it was completely dissolved to prepare a silver precursor solution with a concentration of 100 mM.
A titanium mesh acid-treated with oxalic acid (10 weight percent (wt. %)) was dip-coated by adding it to the prepared silver precursor solution and dried at 80° C. on a hot plate, and this process was repeated three times. Afterwards, a silver-coated titanium electrode was manufactured through a process of heat-treating at 300° C. for one hour.
Iridium chloride hydrate (Sigma) was added to a mixed solvent of distilled water/ethanol (volume ratio 1:1), and then sonicated and stirred until it was completely dissolved to prepare an iridium precursor solution with a concentration of 6.7 mM.
The silver-coated titanium electrode was dip-coated by adding it to the prepared iridium precursor solution and dried at 80° C. on a hot plate, and this process was repeated three times. Afterwards, an iridium-silver/titanium (Ir—Ag/Ti) electrode coated with silver and iridium was manufactured through a process of heat-treating at 300° C. for one hour.
An electrode was manufactured in the same manner as in Example 1, except that the process of adding the titanium mesh to a silver precursor solution was not performed.
An electrode was manufactured in the same manner as in Example 1, except that the process of adding the silver-coated titanium mesh to an iridium precursor solution was not performed.
IrO2 black (100% by weight, Alfa Aesar), a commercial anode catalyst, was used to prepare an IrO2 electrode.
spectroscopy (EDS) detector, EDS mapping analysis results for the electrode of Example 1 were obtained, and the results are shown in
Referring to
The metal crystal planes of the electrodes of Example 1, Comparative Example 1, and Comparative Example 2 were confirmed using X-ray diffraction (XRD; manufactured by PANalytical). The measurement was performed at 40 kV and 100 mA using Cu Kα radiation in a range of 10° to 80° at a scan speed of 6° per minute at intervals of 0.01°, and the results are shown in
Referring to
In addition, the electronic structure of the metal present on the electrode surface was confirmed through X-ray photoelectron spectroscopy (XPS) for the electrodes of Example 1 and Comparative Example 1, and the results are shown in
Referring to
In addition, for the electrodes of Example 1 and Comparative Example 3, the content of iridium (% by weight) present in the catalyst layer of each of the manufactured electrodes was obtained using inductively coupled plasma atomic emission spectroscopy (ICP-AES, NexION 300X), and the results are shown in
Referring to
The electrodes of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were used as a working electrode, Ag/AgCl (sat. 3 M KCl) was used as a reference electrode, and a graphite rod was used as a counter electrode to measure the polarization of the OER for the electrodes of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3. Each electrode was put into a 0.5 M H2SO4 acid solution, and OER was performed at a scan rate of 10 mV/s and room temperature.
The polarization results for the OER are shown in
Referring to
In Example 1, an overpotential of only 287 mV was required to obtain a current density value of 10 mAcm−2, which is a value 15 mV smaller than that of Comparative Example 3 and 53 mV smaller than that of Comparative Example 1.
As confirmed through the ICP analysis results of Example 1, it can be seen that although Example 1 had a significantly lower catalyst metal loading amount than that of Comparative Example 3, the OER performance of Example 1 was superior to Comparative Example 3.
In other words, it can be assumed that in the electrode of Example 1, as both iridium and silver were deposited on a titanium mesh and interact with each other, the electronic structure of iridium, which was the active metal, was changed, and so the OER performance was significantly improved.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0136656 | Oct 2023 | KR | national |
