Patent Application
20220324882
Aspects of the present disclosure generally relate to functionalized metals, to processes for producing functionalized metals, and to uses of functionalized metals as, e.g., sensing materials for chemiresistive sensors.
Chemiresistive sensors change their electrical resistance in response to variations in the chemical environment based on chemical interactions between the sensing material of the sensor and the analyte. Because the sensing material has an inherent resistance, interactions (e.g., bonding or absorption) of the analyte to the sensing material restricts the flow of electrons in the sensing material, causing the resistance of the sensing material to change. Chemiresistive sensors to detect various analytes, such as ammonia (NH3), find use in a variety of applications. For example, such sensors are used in industrial situations where gases pose a risk to worker safety, automotive applications to detect gas emissions, as well as environmental gas analysis where field-portable monitors based on chemiresistive sensors enable measuring and monitoring of trace amounts of gases.
Conventional sensing materials for chemiresistive sensors include metal oxides, conducting polymers, or carbon nanostructures as the sensing material. Such sensing materials, however, suffer from various drawbacks. For example, conducting polymers are thermally unstable and cannot be used at temperatures where gas-solid interactions proceed rapidly. As another example, metal oxides such as SnO2 require high operating temperatures for analyte selectivity. Carbon nanostructures lack sensitivity, rendering them inoperable at low concentration levels of gaseous species. Moreover, the fabrication of nanostructures can be complex. Besides these drawbacks of analyte selectivity, sensitivity, and long-term stability issues, chemiresistive sensors made of state-of-the-art sensing materials lack portability and have poor response time.
There is a need for improved materials, processes for making such materials, and to uses of such materials as, e.g., sensing materials, that overcome one or more of the aforementioned deficiencies of conventional sensing materials.
Aspects of the present disclosure generally relate to functionalized metals, to processes for producing functionalized metals, and to uses of functionalized metals, e.g., sensing materials for chemiresistive sensors.
In an aspect, a process for producing a functionalized metal is provided. The process includes introducing, under first conditions, a first precursor comprising a Group 10 to Group 14 metal with an amine to form a second precursor comprising the Group 10 to Group 14 metal. The process further includes introducing, under second conditions, the second precursor with a third precursor to form the functionalized metal, the third precursor comprising an organic material having the formula HS—R—COOH, wherein R is an unsubstituted hydrocarbyl, a substituted hydrocarbyl, an unsubstituted alkoxy, or a substituted alkoxy.
In another aspect, a composition is provided. The composition includes a Group 10 to Group 14 metal, and an organic group bonded to the Group 10 to Group 14 metal, the organic group comprising S—R—COOH, wherein
represents a bond to the Group 10 to Group 14 metal; and R is an unsubstituted hydrocarbyl, a substituted hydrocarbyl, an unsubstituted alkoxy, or a substituted alkoxy.
In another aspect, a device for detecting an analyte is provided. The device includes a substrate, a source electrode and a drain electrode disposed on the substrate, and a film disposed on a surface of the substrate. The film includes a Group 10 to Group 14 metal and an organic group bonded to the Group 10 to Group 14 metal, the organic group comprising S—R—COOH, wherein
represents a bond to the Group 10 to Group 14 metal, and R is an unsubstituted hydrocarbyl, a substituted hydrocarbyl, an unsubstituted alkoxy, or a substituted alkoxy.
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary aspects and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective aspects.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one example may be beneficially incorporated in other examples without further recitation.
Aspects of the present disclosure generally relate to functionalized metals and to processes for producing functionalized metals. The functionalized metals can be utilized for, e.g., analyte sensing in a variety of applications including gas monitoring in industrial, transportation, and environmental settings. In these and other applications, the functionalized metals can be at least a portion of a sensing material of a sensor device (e.g., chemiresistive sensor). Briefly, the functionalized metal includes a metal bound to an organic group (also referred to as an organic functional group). The organic group includes a mercapto moiety (or thiol moiety) and a carboxyl moiety. The metal is bound to the sulfur atom of the mercapto moiety such that the carboxyl moiety is located distal to the metal. During analyte sensing, the carboxyl moiety can interact with an analyte, and a change in resistance due to the interaction is detected, monitored, measured, determined, or otherwise sensed.
With respect to ammonia sensing, conducting polymers, semiconductive metal oxides, and nanostructures have been heavily investigated as sensing materials. While conducting polymers can be utilized for room temperature detection of ammonia, their lack of long-term stability and sensitivity to humidity and air remain challenges to their implementation. While semiconductive metal oxides (e.g., SnO2) exhibit better stability than conducting polymers, conventional sensors incorporating such metal oxides must operate at temperatures above 400° C. for high selectivity.
In contrast to conventional sensing materials, the functionalized metals described herein can operate at room temperature (e.g., from about 15° C. to about 25° C.). The functionalized metals described herein also exhibit excellent sensitivity. For example, target ammonia species can be detected at concentration levels in the parts-per-million (ppm) range and parts-per-billion (ppb) range, even in the presence of other gases such as carbon monoxide (CO), nitrogen dioxide (NO2), and methane (CH4).
The present disclosure generally relates to functionalized metals, and more specifically to carboxyl functionalized metals. With its free carboxyl group (COOH) or carboxylate ion (COO−), such functionalized metals can be useful for, e.g., detecting, monitoring, measuring, determining, or otherwise sensing analytes such as ammonia.
The functionalized metal can be in the form of a complex, a coordination compound, or the like. The functionalized metal can be a composition or form a portion of a composition. The functionalized metal(s) can be in the form of a structure such as particles (nanoparticles, microparticles, or macroparticles), a monolayer film, a multilayer film, or other structure as described below.
The functionalized metal includes, or is selected from, one or more elements (e.g., metals) from Group 10 to Group 14 of the periodic table of elements, such as Ni, Pd, Pt, Cu, Ag, Au, Cd, Hg, Zn, Al, Ga, In, Tl, Sn, Pb, or combinations thereof. The Group 10 to Group 14 metal is bound (chemically and/or physically) to one or more organic groups. The organic group(s) can have the formula:
S—R—X1,
wherein: “” represents a bond to the Group 10 to Group 14 metal;
X1 is, or is selected from, carboxyl (COOH) or carboxylate ion (COO−); and
R is, or is selected from, an unsubstituted hydrocarbyl (such as a C1-C100 unsubstituted hydrocarbyl, such as C1-C40 unsubstituted hydrocarbyl, such as C1-C20 unsubstituted hydrocarbyl, such as C1-C10 unsubstituted hydrocarbyl, such as C1-C6 unsubstituted hydrocarbyl), a substituted hydrocarbyl (such as a C1-C100 substituted hydrocarbyl, such as C1-C40 substituted hydrocarbyl, such as C1-C20 substituted hydrocarbyl, such as C1-C10 substituted hydrocarbyl, such as C1-C6 substituted hydrocarbyl), an unsubstituted alkoxy (such as a C1-C100 unsubstituted alkoxy, such as C1-C40 unsubstituted alkoxy, such as C1-C20 unsubstituted alkoxy, such as C1-C10 unsubstituted alkoxy, such as C1-C6 alkoxy), a substituted alkoxy (such as a C1-C100 substituted alkoxy, such as C1-C40 substituted alkoxy, such as C1-C20 substituted alkoxy, such as C1-C10 substituted alkoxy, such as C1-C6 substituted alkoxy), an unsubstituted aryl (such as a C4-C100 unsubstituted aryl, such as C4-C40 unsubstituted aryl, such as C4-C20 unsubstituted aryl, such as C4-C10 unsubstituted aryl), or a substituted aryl (such as a C4-C100 substituted aryl, such as a C4-C40 substituted aryl, such as C4-C20 substituted aryl, such as C4-C10). R can be can be saturated or unsaturated, linear or branched, cyclic or acyclic, aromatic or non-aromatic.
In at least one aspect, and when R is a substituted hydrocarbyl, a substituted alkoxy, or a substituted aryl, at least one carbon of the substituted hydrocarbyl, the substituted alkoxy, the substituted aryl has been substituted with at least one heteroatom or heteroatom-containing group, such as one or more elements from Group 13-Group 17 of the periodic table of the elements, such as halogen (e.g., F, Cl, Br, or I), O, N, Se, Te, P, As, Sb, S, B, Si, Ge, Sn, Pb, and the like, such as NR*2, OR* (e.g., OH or O2H), SeR*, TeR*, PR*2, AsR*2, SbR*2, SR*, SOX (where x=2 or 3), BR*2, SiR*3, GeR*3, SnR*3, PbR*3, and the like, where each R* is independently hydrogen, a hydrocarbyl radical (e.g., C1-C10), or two or more R* may join together to form a substituted or unsubstituted, fully saturated, partially unsaturated, fully unsaturated, aromatic, cyclic, or polycyclic ring structure. “Alkoxy” includes ethers and polyethers.
R can include polymers, such as homopolymers and copolymers. Illustrative, but non-limiting, examples of polymers can include, or can be selected from, polyglycols (also called polyethers, polyether glycols or polyols), such as polyethylene glycol (PEG), polyethylene oxide (PEO), polyoxyethylene (POE), polypropylene glycol (PPG), polypropylene oxide (PPDX), polyoxypropylene (POP), polytetramethylene glycol (PTMG), polytetramethylene ether glycol (PTMEG), polytetrhadrofuran, polyacetal, and paraformaldehyde; polyaryls such as polymers having styrene, aniline; polyolefins such as polyethylene or polypropylene; polyesters such as polyethylene terepthalate (PET); polyureas and block copolymers thereof such as polyurethaneureas; polyurethanes, including polyurethane block copolymers; polyethers, including polyether copolymers such as polyether-polyurea copolymers; polyparaphenylenevinylenes, polyanilines, polyazines, polythiophenes, poly-p-phenylene sulfides, polyfuranes, polypyrroles, polyselenophene, and/or polyacetylenes. The average number molecular weight (Mn) of the polymers can be from about 250 g/mol to about 100,000 g/mol, such as from about 450 g/mol to about 50,000 g/mol, such as from about 650 g/mol to about 25,000 g/mol, such as from about 900 g/mol to about 10,000, such as from about 2,000 g/mol to about 7,500, such as from about 3,000 g/mol to about 6,000 g/mol, such as from about 4,000 to about 5,000 g/mol.
In at least one aspect, the organic group has the formula:
HS—CxHy—(COOH)z,
wherein:
x is a positive number such as about 1 or more, such as from about 1 to about 5,000, such as from about 1 to about 500, such as from about 1 to about 50, such as from about 1 to about 10;
y is a positive number such as about 1 or more, such as from about 1 to about 10,000, such as from about 1 to about 1,000, such as from about 1 to about 100, such as from about 1 to about 20; and
z is a positive number such as about 1 or more, such as from about 1 to about 50, such as from about 1 to about 10, such as from about 1 to about 3.
The carbon chain CxHy can be a substituted hydrocarbyl or unsubstituted hydrocarbyl, substituted alkoxy or unsubstituted alkoxy, substituted aryl or unsubstituted aryl, polymeric or non-polymeric, saturated or unsaturated, linear or branched, cyclic or acyclic, aromatic or non-aromatic as described herein.
Illustrative, but non-limiting, examples of precursors of the organic group include, or be selected from, mercaptosuccinic acid (MSA), 3-mercaptopropionic acid (MPA), mercaptopoly(ethylene glycol) carboxylic acid, thioglycolic acid, thiolactic acid, mercaptoisobutyric acid, mercaptobutyric acid, mercaptohexanoic acid, cysteine, mercaptooctanoic acid, mercaptoundecanoic acid, mercaptododecanoic acid, mercaptohexadecanoic acid, homocysteine, N-acetyl-cysteine, glutathione, mercaptobenzoic acid, mercaptophenylacetic acid, or combinations thereof in any suitable proportion. The structures of MSA (1), MPA (2), and mercaptopoly(ethylene glycol) carboxylic acid (3) are
With respect to mercaptopoly(ethylene glycol) carboxylic acid (3), p is a positive number greater than about 1, such as about 2 or more, such as about 5 or more, such as from about 10 to about 1,000, such as from about 15 to about 500, such as from about 20 to about 200, such as from about 50 to about 150, such as from about 75 to about 125. In some aspects, the average number molecular weight (Mn) of the mercaptopoly(ethylene glycol) carboxylic acid can be from about 250 g/mol to about 100,000 g/mol, such as from about 450 g/mol to about 50,000 g/mol, such as from about 650 g/mol to about 25,000 g/mol, such as from about 900 g/mol to about 10,000, such as from about 2,000 g/mol to about 7,500, such as from about 3,000 g/mol to about 6,000 g/mol, such as from about 4,000 to about 5,000 g/mol.
The organic group can include, or be selected from, 3-mercaptopropionic acid, mercaptosuccinic acid, mercaptopoly(ethylene glycol) carboxylic acid, or combinations thereof.
In some aspects, the functionalized metal is represented by:
Mm(S—R—X1)m,
wherein m is a positive number from about 3×102 to about 1×1021, such as from about 3×105 to about 1×1018, such as from about 3×108 to about 1×1015, such as from about 3×1010 to about 1×1012;
n is a positive number from about 1 to about 1×1014, such as from about 1×102 to about 1×1012, such as from about 1×104 to about 1×1010, such as from about 1×106 to about 1×108;
and M, R, and X1 are described above. The metal (M) is bound, chemically and/or physically (e.g., covalent, dative, ionic, etc.), to the sulfur atom of the organic group such that a metal-sulfur (M—S) bond is formed.
A ratio of m to n can be from about 300:1 to about 1×107:1, such as from about 3×103:1 to about 1×106:1, such as from about 3×105:1 to about 1×105:1.
In at least one aspect, the organic group comprises, or is selected from,
or combinations thereof, wherein:
“” represents a bond to the Group 10 to Group 14 metal; and
p is a positive number greater than about 1, such as about 2 or more, such as about 5 or more, such as from about 10 to about 1,000, such as from about 15 to about 500, such as from about 20 to about 200, such as from about 50 to about 150, such as from about 75 to about 125.
The average number molecular weight (Mn) of the mercaptopoly(ethylene glycol) carboxylic acid can be those described above.
In some aspects, and when the functionalized metal is in the form of particles, an average particle size of the particles is from about 2 nm to about 2000 μm, such as from about 20 nm to about 200 μm, such as from about 200 nm to about 20 μm, such as from about 500 nm to about 2 μm. In at least one aspect, the average particle size of the particles is from about 1 nm to about 100 nm, such as from about 5 nm to about 50 nm, such as from about 10 nm to about 25 nm. The average particle size is measured by transmission electron spectroscopy (TEM). For spherical particles, the average particle size is the average diameter as measured by TEM, and for non-spherical particles, the average particle size is an equivalent edge length. The equivalent edge length is measured from TEM.
In some aspects, and when the functionalized metal is in the form of particles, an average particle surface area of the particles can be from about 12.56 nm2 to about 1.256×107 μm2, such as from about 1256 nm to about 1.256×105 μm, such as from about 12.56 μm to about 1.256×103 μm. The average particle surface area of the particles is determined by the equation
surface area=4πr2
where r is the radius of the spherical particle as determined from the diameter according to TEM.
In some aspects, the functionalized metal can have a molar ratio of Group 10 to Group 14 metal(s) to sulfur atom(s) that is about 1:1 to about 1×107:1, such as from about 1:1 to about 1×105:1, such as from about 1:1 to about 1×103:1 to about. In at least one aspect, the functionalized metal has a molar ratio of Group 10 to Group 14 metal(s) to sulfur atom(s) from about 10:1 to about 100:1, such as from about 20:1 to about 80:1, such as from about 30:1 to about 70:1, such as from about 40:1 to about 60:1. In other aspects, the molar ratio of Group 10 to Group 14 metal(s) to sulfur atom(s) is from about 1:1 to about 1000:1, such as from about 1:1 to about 800:1, such as from about 1:1 to about 500:1, such as from about 1:1 to about 200:1, such as from about 1:1 to about 50:1, such as from about 1:1 to about 5:1.
For the functionalized metal, the molar ratio of Group 10 to Group 14 to sulfur atom(s) is measured by transmission electron microscopy of the functionalized metal being analyzed.
For processes for producing a functionalized metal (described below), the molar ratio of the Group 10 to Group 14 metal(s) to sulfur atom(s) of the functionalized metal is determined based on the starting material molar ratio used for the synthesis.
The present disclosure also relates to processes for forming functionalized metals such as those described above.
The process 200 can include introducing, under first conditions, a first precursor comprising one or more elements (e.g., metals) from Group 10 to Group 14 of the periodic table of elements with an amine to form a second precursor comprising the Group 10 to Group 14 metal at operation 210. The second precursor can be, e.g., an amine-stabilized metal. “Second precursor” and “amine-stabilized metal” are used interchangeably. The second precursor can be in the form of, e.g., nanoparticles.
As a non-limiting example, the second precursor can be an alkylamine-stabilized metal particle such as an alkylamine-stabilized gold particle. The amine can act as a solvent and/or a stabilizer.
According to at least some aspects, the first precursor comprising one or more elements from Group 10 to Group 14 of the periodic table of elements includes Ni, Pd, Pt, Cu, Ag, Au, Cd, Hg, or combinations thereof. The first precursor can also include one or more ligands. Such ligands can include, or can be selected from, halide (e.g., I−, Br−, Cl−, or F−), acetylacetonate (O2C5H7−), hydride (H−), SCN−, NO2−, NO3−, N3−, OH−, oxalate (C2O42), H2O, acetate (CH3COO−), O2−, CN−, OCN−, OCN−, CNO−, NH2−, NH2−, NC−, NCS−, N(CN)2−, pyridine (py), ethylenediamine (en), 2,2′-bipyridine (bipy), PPh3, or combinations thereof. In some aspects, the first precursor can include metal acetates, metal acetylacetonates, metal halides, and/or metal nitrates. As illustrative, but non-limiting, examples, the first precursor can include, or be selected from, chloroauric acid (HAuCl4), copper acetylacetonate Cu(O2C5H7)2, silver nitrate (AgNO3), or combinations thereof.
The amine can be a primary amine, a secondary amine, a tertiary amine, or combinations thereof. The amine can include an unsubstituted hydrocarbyl or a substituted hydrocarbyl (as described above) bonded to the nitrogen of the amine, where the unsubstituted hydrocarbyl or substituted hydrocarbyl can be saturated or unsaturated, linear or branched, cyclic or acyclic, aromatic or non-aromatic. Illustrative, but non-limiting, examples of amines include oleylamine (OLA), octadecylamine (ODA), hexadecylamine (HDA), dodecylamine (DDA), tetradecylamine (TDA), or combinations thereof.
In some examples, the first precursor is introduced to more than one amine, where each amine is in suitable proportions relative to the first precursor. As non-limiting examples, the first precursor can be introduced to OLA and TDA, or DDA and TDA, or HDA and TDA, or OLA and HDA. Other amine combinations are contemplated.
For operation 210, the molar ratio of materials can be adjusted as desired. In some examples, the molar ratio of first precursor to amine(s) is from about 1:1 to about 1×107:1, such as from about 1:1 to about 1×105:1, such as from about 1:1 to about 1×103:1, such as from about 1:1 to about 100:1, such as from about 1:1 to about 50:1, such as from about 1:1 to about 20:1, such as from about 1:1 to about 5:1.
The first conditions in operation 210 can include a reaction temperature and a reaction time. The reaction temperature of operation 210 can be from about 100° C. to about 320° C., such as from about 110° C. to about 310° C., such as from about 120° C. to about 300° C., such as from about 130° C. to about 290° C., such as from about 140° C. to about 280° C., such as from about 150° C. to about 270° C., such as from about 160° C. to about 260° C., such as from about 170° C. to about 250° C., such as from about 180° C. to about 240° C., such as from about 190° C. to about 230° C., such as from about 200° C. to about 220° C. In some aspects, the reaction temperature of operation 210 is from about 150° C. to about 280° C. or from about 180° C. to about 250° C. Higher or lower temperatures can be used when appropriate. The reaction time of operation 210 can be at least about 1 minute (min), such as from about 5 min to about 6 hours (h), such as from about 10 min to about 5.5 h, such as from about 15 min to about 5 h, such as from about 30 min to about 4 h, such as from about 45 min to about 3 h, such as from about 1 h to about 2 h. The reaction time of operation 210 can be more or less depending on, e.g., the level of conversion desired. Any reasonable pressure can be used during operation 210.
The first conditions of operation 210 can include stirring, mixing, and/or agitation to, e.g., ensure homogeneity of the mixture. The first conditions can also include performing the reaction under a non-reactive gas, such as N2 and/or Ar. The mixture of the first precursor and the amine can be degassed with these or other non-reactive gases prior to, during, and/or after, adjusting the temperature. After a suitable time, the reaction mixture comprising the reaction product (e.g., the second precursor) of operation 210 can be subjected to filtration, separation, cleaning, quenching, washing, purification, and/or other suitable processes to remove undesired components and isolate the second precursor from the other components of the reaction mixture. For example, the mixture comprising the reaction product of operation 210 can be centrifuged to separate the second precursor particles from the mixture. Additionally, or alternatively, the second precursor can be washed with polar solvent(s), such as water, acetone, ethanol, methanol, or combinations thereof, and/or non-polar solvent(s), such as hexane, pentane, toluene, or combinations thereof. Other solvents for washing can include ether solvents such as diethyl ether and tetrahydrofuran; chlorocarbon solvents such as dichloromethane and chloroform; as well as ethyl acetate, dimethylformamide, acetonitrile, benzene, isopropanol, n-butanol, n-propanol. Mixtures of two or more solvents such as those listed above, in suitable proportions, can be utilized for washing or otherwise separating the second precursor from other components in the reaction mixture. As an example, a solvent can be added to the second precursor and centrifuged. The supernatant can be discarded and the remaining pellet can be dispersed in a suitable solvent or mixture of solvents such as those listed above. The resultant pellet and solvent(s) can then be centrifuged to obtain the second precursor.
The process 200 can further include introducing, under second conditions, the second precursor with a third precursor to form the functionalized metal at operation 220. Operation 220 can be referred to as a ligand exchange reaction. The functionalized metal can be a reaction product of operation 220 where the sulfur atom of the third precursor is bound to a metal. The third precursor includes, or is, the starting material that contains the organic group as described above. Illustrative, but non-limiting, examples of the third precursor include MSA, MPA, mercaptopoly(ethylene glycol) carboxylic acid, thioglycolic acid, thiolactic acid, mercaptoi sobutyric acid, mercaptobutyric acid, mercaptohexanoic acid, cysteine, mercaptooctanoic acid, mercaptoundecanoic acid, mercaptododecanoic acid, mercaptohexadecanoic acid, homocysteine, N-acetyl-cysteine, glutathione, mercaptobenzoic acid, mercaptophenylacetic acid, or combinations thereof in any suitable proportion. Other compounds comprising organic groups are described above.
For operation 220, the molar ratio of materials can be adjusted as desired. In some examples, the molar ratio of second precursor to third precursor is from about 1:1 to about 1×107:1, such as from about 10:1 to about 1×106:1, such as from about 100:1 to about 1×105:1, such as from about 1×103:1 to about 1×104:1. In other aspects, the molar ratio of second precursor to third precursor is from about 1:1 to about 100:1, from about 1:1 to about 80:1, from about 1:1 to about 50:1, from about 1:1 to about 20:1, from about 1:1 to about 10:1, or from about 1:1 to about 5:1.
Operation 220 can include introducing the second precursor and the third precursor with a solvent such as those described above, such as water. The reaction mixture formed, which includes the second precursor, the third precursor, and an optional solvent can be stirred, mixed, and/or agitated to, e.g, ensure homogeneity of the mixture. The second conditions in operation 220 can include a reaction temperature and a reaction time. The reaction temperature of operation 220 can be from about 20° C. to about 320° C., such as from about 110° C. to about 310° C., such as from about 120° C. to about 300° C., such as from about 130° C. to about 290° C., such as from about 140° C. to about 280° C., such as from about 150° C. to about 270° C., such as from about 160° C. to about 260° C., such as from about 170° C. to about 250° C., such as from about 180° C. to about 240° C., such as from about 190° C. to about 230° C., such as from about 200° C. to about 220° C. Higher or lower temperatures can be used when appropriate. The reaction time for operation 220 can be at least about 1 minute (min), such as from about 5 min to about 48 h, such as from about 10 min to about 24 h, such as from about 30 min to about 10 h, such as from about 1 h to about 8 h, such as from about 2 h to about 7 h, such as from about 3 h to about 6 h, such as from about 4 h to about 5 h. The reaction time for operation 220 can be more or less depending on, e.g., the level of conversion desired. Any reasonable pressure can be used during the reaction to form the functionalized metal of operation 220.
The second conditions can also include performing the reaction under a non-reactive gas, such as N2 and/or Ar. The mixture of the second precursor, the third precursor, and the optional solvent, can be degassed with these or other non-reactive gases prior to, during, and/or after, adjusting the temperature. After a suitable time, the reaction mixture comprising the reaction product of operation 220 (e.g., the functionalized metal) can be subjected to filtration, separation, cleaning, quenching, washing, purification, and/or other suitable processes to remove undesired components and isolate the functionalized metal from the other components of the reaction mixture. For example, the mixture comprising the reaction product of operation 220 can be centrifuged to separate the functionalized metal (which may be in the form of particles) from the mixture. Additionally, or alternatively, the functionalized metal can be washed with polar solvent(s), such as water, acetone, ethanol, methanol, or combinations thereof, and/or non-polar solvent(s), such as hexane, pentane, toluene, or combinations thereof. Other solvents for washing can include ether solvents such as diethyl ether and tetrahydrofuran; chlorocarbon solvents such as dichloromethane and chloroform; as well as ethyl acetate, dimethylformamide, acetonitrile, benzene, isopropanol, n-butanol, n-propanol. Mixtures of two or more solvents such as those listed above, in suitable proportions, can be utilized for washing or otherwise separating the functionalized metal from other components in the reaction mixture. As an example, a solvent can be added to the functionalized metal and centrifuged. The supernatant can be discarded and the remaining pellet can be dispersed in a suitable solvent or mixture of solvents such as those listed above. The resultant pellet and solvent(s) can then be centrifuged to obtain the functionalized metal.
The present disclosure also relates to uses of the functionalized metals described herein. In some aspects, the functionalized metal can be used in gas sensing applications and/or can be incorporated into devices (e.g., gas sensor devices, chemoresistive sensors) useful for such applications. In some aspects, the functionalized metal can be utilized to detect, monitor, measure, determine, or otherwise sense, the presence of analytes (such as amines, such as NH3) in a variety of settings or environments. As an example, the functionalized metal can be incorporated into a chemoresistive sensor to detect, monitor, measure, determine, or otherwise sense, the presence of NH3 formed in, e.g., the catalytic converter of an automobile. In addition to NH3, engine exhaust contains various gases such as CO, CO2, O2, N2O, NO, NO2, H2O, and CH4. Cross interference effects from these gases can be detrimental to NH3 sensing. As described herein, use of the functionalized metal can overcome such cross-interference effects due to, e.g., its selectivity for NH3. Such sensors can also be used in other transportation applications such as other land vehicles (trucks), trains, aircraft, and watercraft.
As another example, the functionalized metal can be incorporated into field-portable monitors for environmental monitoring. Here, the sensitivity and selectivity of the functionalized metal enables detection, monitoring, measurement, determining, or otherwise sensing, of trace amounts of an analyte. As another example, the functionalized metal can be incorporated into chemoresistive sensors useful in personal protective equipment, industrial settings, and other applications, as an alert for the presence of an analyte. In these and other applications, the functionalized metal can be the sensing material of a sensor or the sensing material of the sensor can include the functionalized metal.
The functionalized metal 401 can be deposited using various techniques. Deposition techniques can include syringe coating, dip coating, knife edge coating, and/or spin coating, micro-inject coating, and 3D print coating to produce a particle, a film, or other suitable structure on the substrate 402 and/or electrodes. For deposition, the functionalized metal 401 can be in the form of a solution or suspension in a solvent such as a hydrophilic solvent, such as water, ethanol, and/or acetone. After depositing the functionalized metal 401, the device 400 can be dried by air drying at room temperature (e.g., about 15° C. to about 25° C.) or heated in an oven to evaporate the solvent.
The functionalized metal 401 acts as a sensing material that changes its electrical resistance in response to variations in the chemical environment around the device 400. The change in the resistance of the functionalized metal 401, between the absorbed state and desorbed state, can be used to detect, monitor, measure, determine, or otherwise sense, an analyte such as NH3.
In operation, a voltage is applied to the electrodes 404a, 404b of the device 400 and the current is measured. Based on the applied voltage and the measured current, the resistance change of the functionalized metal 401 can be calculated using Ohm's law.
In operation, a voltage is applied to the electrodes 404a, 404b of the device 450 and the current is measured. Based on the applied voltage and the measured current, the resistance of the functionalized metal 401 in the presence of an analyte can be calculated using Ohm's law.
As shown, the device 450 can further include a controller 470, the controller being electrically coupled to various elements of the device 450. The controller is used to measure the current flowing through the functionalized metal 401 and calculate a resistance (R) of the functionalized metal 401. The controller 470 can also be utilized to control the voltage source 455. The controller 470 can also be used to send a signal to an input/output device, such as a display unit or an audio device (not shown) indicating a resistance change. The controller 470 can include a processor 472, memory 474, and support circuits 476.
The processor 472 may be one of any suitable form of general purpose microprocessor, or a general purpose central processing unit (CPU), each of which can be used in an industrial setting, such as a programmable logic controller (PLC), supervisory control and data acquisition (SCADA) systems, or other suitable industrial controller. The memory 474 is non-transitory and may be one or more of readily available memory such as random access memory (RAM), read only memory (ROM), or any other form of digital storage, local or remote. The memory 474 contains instructions, that when executed by the processor 472, can facilitate one or more operations of, e.g., applying a voltage, the current measurement, the resistance calculation. The instructions in the memory 474 are in the form of a program product such as a program that implements the method of the present disclosure. The program code of the program product may conform to any one of a number of different programming languages. Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips, or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, are examples of the present disclosure. In one example, the disclosure may be implemented as the program product stored on a computer-readable storage media (e.g., memory 474) for use with a computer system (not shown). The program(s) of the program product define functions of the disclosure, described herein.
The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use aspects of the present disclosure, and are not intended to limit the scope of aspects of the present disclosure. Further, while the present disclosure refers to “nanoparticles”, it will be appreciated that the disclosure may be applied to particles having a larger size (e.g., “microparticles” and “macroparticles”). Similarly, while the present disclosure refers to films, it will be appreciated that the disclosure may be applied to layer(s), monolayer films, and multilayer films. In addition, efforts have been made to ensure accuracy with respect to numbers used (e.g. amounts, dimensions, etc.) but some experimental errors and deviations should be accounted for.
Chloroauric acid (HAuCl4), copper acetylacetonate, silver nitrate (AgNO3), OLA, DDA, HDA, ODA, mercaptopoly(ethylene glycol) carboxylic acid (SH-PEG-COOH), 3-mercaptopropionic acid (MPA), and mercaptosuccinic acid (MSA) were purchased from Sigma Aldrich. All chemicals were used as received.
X-ray diffraction patterns were obtained using a Bruker D8 Advance X-ray diffractometer with Cu Ka radiation operated at a tube voltage of 40 kV and a current of 40 mA. Surface morphologies were investigated using a QUANTA™ FEG 650 scanning electron microscope (from FEI Tecnai) with a field emitter as the electron source. Transmission electron microscopy (TEM) images were captured using an FEI Tecnai 20 microscope with an accelerating voltage of 200 kV. FT-IR spectra were obtained using a NEXUS 670 ThermoNicolet FT-IR. For characterization by FT-IR, sample suspensions were drop casted onto KBr crystal plates and allowed to dry as a film prior to the measurement.
A UV-Vis spectrometer (Cary 5000) was used to record the extinction spectra of the metal nanoparticles. For characterization by UV-Vis spectrometry, solvents sufficient to disperse the functionalized metal (e.g., functionalized metal nanoparticles) were used such as hydrophobic solvents, such as hexane, toluene, and/or chloroform.
Example 1A. Gold Nanoparticles: HAuCl4 (50 mg) was mixed with oleylamine (3 mL) and tetradecylamine (3 g) in a flask under an Ar and/or N2 environment to form a solution/suspension. After degassing for 10 minutes, the solution/suspension was heated to 150° C. under Ar and/or N2. After keeping the solution/suspension at this temperature for 60 minutes, the solution was cooled to room temperature. The products were isolated by centrifugation at 6000 rpm for 15 minutes, and the supernatant was discarded. The pellet was then washed (2×) with hexane and ethanol, sequentially. The second precursor (e.g., gold nanoparticles) was stored in a hydrophobic solvent (e.g., hexane, toluene, and/or chloroform). The gold nanoparticles had a molar ratio of gold to amine of about 4:1.
Example 1B. Silver Nanoparticles: AgNO3 (51 mg) was mixed with oleylamine (3 mL) and tetradecylamine (3 g) in a flask under an Ar and/or N2 environment to form a solution/suspension. After degassing for 10 minutes, the solution/suspension was heated to 150° C. under Ar and/or N2. After keeping the solution/suspension at this temperature for 60 minutes, the solution was cooled to room temperature. The products were isolated by centrifugation at 6000 rpm for 15 minutes, and the supernatant was discarded. The pellet was then washed (2×) with hexane and ethanol, sequentially. The second precursor (e.g., silver nanoparticles) were stored in a hydrophobic solvent (e.g., hexane, toluene, and/or chloroform). The silver nanoparticles had a molar ratio of silver to amine of about 4:1.
Example 1C. Copper Nanoparticles: Copper acetylacetonate (52 mg) was mixed with oleylamine (3 mL) and tetradecylamine (3 g) in a flask under an Ar and/or N2 environment to form a solution/suspension. After degassing for 10 minutes, the solution/suspension was heated to 150° C. under Ar and/or Na. After keeping the solution/suspension at this temperature for 60 minutes, the solution was cooled to room temperature. The products were isolated by centrifugation at 6000 rpm for 15 minutes, and the supernatant was discarded. The pellet was then washed (2×) with hexane and ethanol, sequentially. The second precursor (e.g., copper nanoparticles) were stored in a hydrophobic solvent (e.g., hexane, toluene, and/or chloroform). The copper nanoparticles had a molar ratio of copper to amine of about 4:1.
The second precursor, e.g., gold nanoparticles (10 mg) from Example 1A, were mixed with mercaptosuccinic (2 mL) acid and water (5 mL), and stirred for 8 hours under an Ar and/or N2 environment while monitoring ligand exchange. The resulting products were washed twice with deionized water by centrifugation at 4000 rpm for 5 minutes. The functionalized metal (MSA-modified Au nanoparticles) were stored in a hydrophilic solvent (e.g., water, acetone, ethanol, and/or methanol) before characterization. Similar procedures were utilized to convert the silver-amine nanoparticles (Example 1B) and copper-amine nanoparticles (Example 1C) to their respective functionalized metal nanoparticles.
Metal nanoparticles modified with different functional groups were also synthesized. Here, similar procedures were used to convert the second precursor to 3-mercaptopropioninc acid-modified Au nanoparticles (MPA-modified Au nanoparticles) and to mercaptopoly(ethylene glycol) carboxylic acid-modified Au nanoparticles (SH-PEG-COOH modified Au nanoparticles).
A sensor device (e.g., device 400) was fabricated with Cr/Au source and drain electrodes 404a, 404b patterned using electron beam lithography on the substrate 402. The substrate 402 for this example was a degenerately doped silicon substrate and used as a backgate. A solution/suspension of the functionalized metal 401 (in this example, MSA-modified Au nanoparticles) is deposited on portions of the substrate 402 and/or electrodes 404a, 404b via micropipette and microsyringe in the form of a solution or suspension in water or other hydrophilic solvent, and then dried at about 15° C. to about 25° C.
Resistance Measurements: The source-drain current (I) was measured as a function of bias voltage and gate voltage applied to the electrodes 404a, 404b under ambient laboratory conditions. Based on the bias voltage (V) (or applied voltage) of about 5 V and the source-drain current (I), resistance (R) or resistance change (ΔR) of the functionalized metal 401 can then be calculated using Ohm's law: R=V|I.
All gas sensing measurements were performed within a stainless steel gas chamber in the background of N2 at room temperature. The mixtures containing different concentrations of the target gas were prepared by diluting the target gas with N2. The total flow rate was maintained at 200 cm3/min with an automated gas delivery system operated by mass flow controllers. The sensors were pretreated in N2 for 2 h before each measurement to acquire a stable baseline. The resistances of the sensors were recorded by a Keysight 34980A multifunction switch/measurement unit. The response value was defined as the ratio between the resistance change of a sensor (ΔR) in the presence of the target gas and the baseline resistance in N2 (R0). The response and recovery time were defined as the time required to reach 90% of its final stable reading upon exposure or removal of the target gas. The voltage applied was 5 V.
Sensitivity of the sensor was evaluated by investigating the between gas (NH3 and NO2) concentration and the magnitude of the sensor response.
While not wishing to be bound by theory, it is believed that the resistance increases because the NH3 molecules coordinate with the carboxyl groups of the example MSA-modified Au nanoparticles. Such coordination increases the average distance between two nanoparticles which the electrons must tunnel through when a voltage is applied and electric current flows, thereby increasing the resistance. The increased resistance upon exposure to NH3 and the decreased resistance upon exposure to NO2 indicates the selectivity of the example MSA-modified Au nanoparticles toward NH3.
In addition,
Specifically,
The selectivity of a sensor device incorporating MSA-modified nanoparticles was also evaluated by exposing the sensor device to various gases—NO, CO2, CO, H2, ethanol, acetone, NH3, NO2, and CH4—at concentrations of ˜25 ppm, ˜100 ppm, ˜200 ppm, and ˜250 ppm in N2.
Functionalized metals, syntheses of functionalized metals, and uses of functionalized metals in, e.g., sensor devices are described herein. The functionalized metals exhibit high-performance detection of NH3. Syntheses of the functionalized metals can be easily scaled-up, with lower production costs, relative to nanostructure-based NH3 sensing materials. The functionalized metals are also fabricated by simpler methods than such nanostructures. Moreover the functionalized metals described herein, and sensor devices incorporating functionalized metals, can operate at room temperature with high sensitivity and high selectivity, whereas conventional materials incorporating semiconductive metal oxides must operate at temperatures above 400° C. for high NH3 selectivity. Overall, the functionalized metals show, e.g., high selectivity, sub-ppm sensitivity, as well as high stability to air, moisture, and time.
The present disclosure provides, among others, the following aspects, each of which can be considered as optionally including any alternate aspects:
Clause 1. A process for producing a functionalized metal, comprising:
HS—R—COOH,
Clause 2. The process of Clause 1, wherein the functionalized metal has the formula:
Mm(S—R—COOH)n,
Clause 3. The process of Clause 1 or Clause 2, wherein R is a polymer having an Mn of about 100,000 g/mol or less.
Clause 4. The process of any one of Clauses 1-3, wherein R is an unsubstituted C1-C20 hydrocarbyl or a substituted C1-C20 hydrocarbyl.
Clause 5. The process of any one of Clauses 1-4, wherein the third precursor comprises mercaptosuccinic acid, 3-mercaptopropionic acid, mercaptopoly(ethylene glycol), or combinations thereof.
Clause 6. The process of any one of Clauses 1-5, wherein the Group 10 to Group 14 metal comprises Ni, Pd, Pt, Cu, Ag, Au, Cd, Hg, Zn, Al, Ga, In, Tl, Sn, Pb, or combinations thereof
Clause 7. The process of any one of Clauses 1-6, wherein the Group 10 to Group 14 metal comprises Au, Ag, Cu, Pt, Pd, Ni, or combinations thereof.
Clause 8. The process of any one of Clauses 1-7, wherein the amine is an alkylamine.
Clause 9. The process of Clause 8, wherein the alkylamine comprises tetradecylamine, oleylamine, octadecylamine, hexadecylamine, dodecylamine, or combinations thereof.
Clause 10. The process of Clause 8 or Clause 9, wherein the Group 10 to Group 14 metal comprises Au, Ag, Cu, or combinations thereof.
Clause 11. The process of any one of Clauses 1-10, wherein the functionalized metal is in the form of nanoparticles having an average particle size of about 2 nm to about 100 nm, as determined by transmission electron microscopy.
Clause 12. A composition, comprising:
S—R—COOH,
Clause 13. The composition of Clause 12, wherein R is a polymer.
Clause 14. The composition of Clause 12 or Clause 13, wherein R is an unsubstituted C1-C20 hydrocarbyl or a substituted C1-C20 hydrocarbyl.
Clause 15. The composition of any one of Clauses 11-14, wherein the organic group comprises
or combinations thereof, wherein:
Clause 16. The composition of any one of Clauses 11-15, wherein p is from about 20 to about 200.
Clause 17. The composition of any one of Clauses 11-16, wherein the Group 10 to Group 14 metal comprises Ni, Pd, Pt, Cu, Ag, Au, Cd, Hg, Zn, Al, Ga, In, Tl, Sn, Pb, or combinations thereof.
Clause 18. The composition of any one of Clauses 11-17, wherein the Group 10 to
Group 14 metal comprises Au, Ag, Cu, Pt, Pd, Ni, or combinations thereof.
Clause 19. The composition of any one of Clauses 11-18, wherein:
Clause 20. A device for detecting an analyte, comprising:
S—R—COOH,
Clause 21. The device of Clause 20, wherein the film is further disposed on a surface of the source electrode, a surface of the drain electrode, or both.
Clause 22. The device of Clause 20 or Clause 21, wherein the device is configured to detect ammonia.
Clause 23. The device of any one of Clauses 20-22, wherein the film comprises a composition of any one of Clauses 12-19.
Clause 24. The device of any one of Clauses 20-23, wherein the device is configured to detect ammonia at a concentration of less than 500 ppm.
Clause 25. A device for detecting an analyte, comprising:
As used herein, and unless otherwise specified, the term “Cn” means hydrocarbon(s) having n carbon atom(s) per molecule, wherein n is a positive integer. The term “hydrocarbon” means a class of compounds containing hydrogen bound to carbon, and encompasses (i) saturated hydrocarbon compounds, (ii) unsaturated hydrocarbon compounds, and (iii) mixtures of hydrocarbon compounds (saturated and/or unsaturated), including mixtures of hydrocarbon compounds having different values of n. Likewise, a “Cm-Cy” group or compound refers to a group or compound comprising carbon atoms at a total number thereof in the range from m to y. Thus, a C1-C50 alkyl group refers to an alkyl group comprising carbon atoms at a total number thereof in the range from 1 to 50.
For purposes of this disclosure, and unless otherwise specified, the terms “hydrocarbyl radical,” “hydrocarbyl group,” or “hydrocarbyl” interchangeably refer to a group consisting of hydrogen and carbon atoms only. A hydrocarbyl group can be saturated or unsaturated, linear or branched, cyclic or acyclic, aromatic, or non-aromatic. For the purposes of this disclosure, and unless otherwise specified, the term “aryl” or “aryl group” interchangeably refers to a hydrocarbyl group comprising an aromatic ring structure therein.
For the purposes of this present disclosure, and unless otherwise specified, the terms “alkoxy” refers to an alkyl or aryl group bound to an oxygen atom, such as an alkyl ether or aryl ether group/radical connected to an oxygen atom and can include those where the alkyl/aryl group is a C1-C10 hydrocarbyl. The alkyl group may be straight chain, branched, or cyclic. The alkyl group may be saturated or unsaturated. Examples of suitable alkoxy can include methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, iso-butoxy, sec-butoxy, tert-butoxy, phenoxyl. “Alkoxy” includes ethers and polyethers.
Chemical moieties of the application can be substituted or unsubstituted unless otherwise specified. For purposes of this disclosure, and unless otherwise specified, a substituted hydrocarbyl, a substituted alkoxy, and a substituted aryl refers to a hydrocarbyl, alkoxy, and aryl radical, respectively, in which at least one hydrogen atom has been substituted with a heteroatom or heteroatom containing group, such as with at least one functional group, such as one or more of halogen (Cl, Br, I, F), NR*2, OR* (e.g., OH or O2H), SeR*, TeR*, PR*2, AsR*2, SbR*2, SR*, SOx (where x=2 or 3), BR*2, SiR*3, GeR*3, SnR*3, PbR*3, and the like or where at least one heteroatom has been inserted within the hydrocarbyl radical, such as one or more of halogen (Cl, Br, I, F), O, S, Se, Te, NR*, PR*, AsR*, SbR*, BR*, SiR*2, GeR*2, SnR*2, PbR*2, and the like, where R* is, independently, hydrogen or a hydrocarbyl.
Where isomers of a named molecule group exist (e.g., n-butanol, sec-butanol, iso-butanol, and tert-butanol), reference to one member of the group (e.g., n-butanol) shall expressly disclose all remaining isomers (e.g., sec-butanol, iso-butanol, and tert-butanol) unless specified to the contrary or the context clearly indicates otherwise. Likewise, reference to a compound without specifying a particular isomer (e.g., butanol) expressly discloses all isomers and stereoisomers (e.g., sec-butanol, iso-butanol, and tert-butanol) unless specified to the contrary or the context clearly indicates otherwise.
“Carboxyl group” and “carboxyl moiety” are used interchangeably herein. “Mercapto moiety” and “thiol moiety” and are used interchangeably herein.
As used herein, a “composition” can include component(s) of the composition and/or reaction product(s) of two or more components of the composition. Compositions of the present disclosure can be prepared by any suitable mixing process.
As is apparent from the foregoing general description and the specific aspects, while forms of the aspects have been illustrated and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby. Likewise, the term “comprising” is considered synonymous with the term “including.” Likewise whenever a composition, an element or a group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “Is” preceding the recitation of the composition, element, or elements and vice versa, e.g., the terms “comprising,” “consisting essentially of,” “consisting of” also include the product of the combinations of elements listed after the term.
For purposes of this present disclosure, and unless otherwise specified, all numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and consider experimental error and variations that would be expected by a person having ordinary skill in the art. For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.
As used herein, the indefinite article “a” or “an” shall mean “at least one” unless specified to the contrary or the context clearly indicates otherwise. For example, aspects comprising “a metal” include aspects comprising one, two, or more metals, unless specified to the contrary or the context clearly indicates only one metal is included.
While the foregoing is directed to aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
