Oxygen evolution reaction catalysts, methods of making and using the same

Abstract

The present disclosure provides an oxygen evolution reaction catalyst and a preparation method and application thereof, and belongs to the technical field of catalysts and the technical field of electrochemistry. The preparation method comprises: performing air calcination on a mixture of an iridium salt, a ruthenium salt, a tungsten salt, an alkali metal nitrate and a carbon-nitrogen material to obtain an oxygen evolution reaction catalyst.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of catalysts and the technical field of electrochemistry, in particular to an oxygen evolution reaction catalyst and a preparation method and application thereof. BACKGROUND

[0002] Oxygen evolution reaction (Oxygen Evolution Reaction, OER) is one of the important electrochemical reactions in the new energy technologies such as water electrolysis hydrogen production and fuel cells. However, due to its complex multi-electron transfer process, OER usually exhibits a high reaction overpotential, which becomes a limiting factor for the efficiency of electrochemical devices, and compared with alkaline conditions, acidic conditions are thermodynamically unfavorable for the oxygen evolution electrocatalysis on the anode side, which puts higher requirements on the selection of active materials.

[0003] In the related art, the acidic OER catalyst is mainly derived from iridium, which has a low global reserve. Iridium-based catalysts have excellent electrocatalytic performance and high stability under acidic conditions, and have become the research focus of acidic OER catalysts. However, iridium resources are scarce and expensive. SUMMARY

[0004] Therefore, in order to at least partially solve at least one of the above-mentioned technical problems, the present disclosure provides an oxygen evolution reaction catalyst and a preparation method and application thereof.

[0005] According to an embodiment of the present disclosure, a preparation method of an oxygen evolution reaction catalyst is provided, comprising: air calcining a mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material to obtain the oxygen evolution reaction catalyst.

[0006] According to an embodiment of the present disclosure, the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material is prepared by heating a dispersion liquid containing iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material until the solvent in the dispersion liquid evaporates to obtain the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material.

[0007] According to an embodiment of the present disclosure, in the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material, the molar ratio of iridium salt to ruthenium salt is 1: (0.1-10).

[0008] According to an embodiment of the present disclosure, in the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material, the molar ratio of the sum of iridium salt and ruthenium salt to tungsten salt is 1: (0.01-0.20).

[0009] According to an embodiment of the present disclosure, in the mixture of the iridium salt, the ruthenium salt, the tungsten salt, the alkali metal nitrate, and the carbon-nitrogen material, a molar ratio of a sum of the iridium salt, the ruthenium salt, and the tungsten salt to the alkali metal nitrate is (1-10):100.

[0010] According to an embodiment of the present disclosure, in the mixture of the iridium salt, the ruthenium salt, the tungsten salt, the alkali metal nitrate, and the carbon-nitrogen material, a mass ratio of the carbon-nitrogen material to the alkali metal nitrate is 1:(50-1000).

[0011] According to an embodiment of the present disclosure, the temperature of the calcination is 300-700°C.

[0012] According to an embodiment of the present disclosure, the time of the calcination is 1-6h.

[0013] According to an embodiment of the present disclosure, the temperature increasing rate of the calcination is 1-10°C / min.

[0014] According to an embodiment of the present disclosure, the temperature of the calcination is 350-400°C.

[0015] According to an embodiment of the present disclosure, the carbon-nitrogen material is selected from one or more of melamine, urea, and a metal organic framework material.

[0016] According to an embodiment of the present disclosure, the alkali metal nitrate is selected from one or more of sodium nitrate, potassium nitrate, and lithium nitrate.

[0017] According to an embodiment of the present disclosure, the iridium salt is selected from one or more of chloro iridate, chloro iridate hydrate, and iridium nitrate.

[0018] According to an embodiment of the present disclosure, the ruthenium salt is selected from one or more of tris nitro nitrosyl ruthenium, ruthenium trichloride hydrate, ruthenium trichloride, and dichloride ruthenium.

[0019] According to an embodiment of the present disclosure, the tungsten salt is selected from one or more of tungsten chloride, oxide, or alkali metal tungsten salt.

[0020] According to an embodiment of the present disclosure, the dispersion liquid containing the iridium salt, the ruthenium salt, the tungsten salt, the alkali metal nitrate, and the carbon-nitrogen material is prepared by mixing a solution containing the iridium salt and a solution containing the ruthenium salt to obtain a first mixed liquid, adding the alkali metal nitrate to the first mixed liquid to obtain a second mixed liquid, and adding a solution containing the tungsten salt and the carbon-based material to the second mixed liquid to obtain the dispersion liquid.

[0021] According to an embodiment of the present disclosure, the concentration of the solution containing the iridium salt is 0.01-1.00 mol / L.

[0022] According to an embodiment of the present disclosure, the concentration of the solution containing the ruthenium salt is 0.02-2.00 mol / L.

[0023] According to an embodiment of the present disclosure, the concentration of the solution containing the tungsten salt is 0.001-0.5 mol / L.

[0024] According to an embodiment of another aspect of the present disclosure, there is provided an oxygen evolution reaction catalyst prepared by the preparation method.

[0025] According to an embodiment of another aspect of the present disclosure, there is provided an application of the oxygen evolution reaction catalyst in the field of electrochemical oxygen production.

[0026] According to an embodiment of the present disclosure, by air calcining a mixture of an iridium salt, a ruthenium salt, a tungsten salt, an alkali metal nitrate and a carbon-nitrogen material, the alkali metal nitrate acts as a fluxing agent and the carbon-nitrogen material acts as a regulating material during the calcination process, which promotes the formation of an oxygen evolution reaction catalyst with a nanosheet structure; and the carbon-nitrogen material can also regulate the valence state and stability of the catalyst during the sintering process, so that a certain low-valence metal exists in the catalyst, which is conducive to the electrical conductivity of the material. The preparation method provided in the embodiment of the present disclosure simplifies the process and is conducive to large-scale production and application.

[0027] The oxygen evolution reaction catalyst provided in the embodiment of the present disclosure has a nanosheet structure, which significantly increases the specific surface area of the catalyst and provides more active sites; by regulating the valence state of the oxygen evolution reaction catalyst, the electrical conductivity and corrosion resistance of the catalyst are enhanced, and the OER catalytic efficiency is further improved. The oxygen evolution reaction catalyst provided in the embodiment of the present disclosure not only has high OER catalytic performance, but also exhibits excellent stability and can work stably in an acidic medium for a long time.

[0028] The oxygen evolution reaction catalyst provided in the embodiment of the present disclosure is not only suitable for electrochemical oxygen pumps, but also has the potential for application in other electrochemical devices in acidic media, such as proton exchange membrane electrolysis cells, etc., which provides new possibilities for the development of new energy technologies. BRIEF DESCRIPTION OF DRAWINGS

[0029] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which:

[0030] Figure 1 FIG. 1 shows a scanning electron microscope image of an oxygen evolution reaction catalyst provided in Embodiment 1 of the present disclosure;

[0031] Figure 2 FIG. 2 shows a scanning electron microscope image of an oxygen evolution reaction catalyst provided in Comparative Example 1 of the present disclosure;

[0032] Figure 3A transmission electron microscope image of the oxygen evolution reaction catalyst according to Example 1 of the present disclosure is shown.

[0033] Figure 4 A transmission electron microscope image of the oxygen evolution reaction catalyst according to Comparative Example 1 of the present disclosure is shown.

[0034] Figure 5 XRD images of the oxygen evolution reaction catalysts according to Example 1 and Comparative Example 1 of the present disclosure are shown.

[0035] Figure 6 Polarization curves of the oxygen evolution reaction catalysts according to Example 1, Comparative Example 1 and Comparative Example 2 of the present disclosure are shown.

[0036] Figure 7 An oxygen production effect diagram of the assembled membrane electrode of the oxygen evolution reaction catalyst according to Example 1 of the present disclosure is shown.

[0037] Figure 8 An oxygen production test curve of the oxygen pump assembled using the oxygen evolution reaction catalysts according to Example 1 and Comparative Example 1 of the present disclosure is shown. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood, however, that the description is merely exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description of the embodiments of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it would be apparent to those skilled in the art that the embodiments of the present disclosure can be practiced without these specific details. In other instances, well-known structures and techniques have been omitted in order to avoid obscuring the concepts of the present disclosure.

[0039] The terms used herein are merely used to describe specific embodiments and are not intended to limit the present disclosure. The term "include" used herein indicates the presence of a feature, step, operation, but does not exclude the presence or addition of one or more other features.

[0040] In the case of using expressions such as "at least one of A, B, and C", it will be understood that the meaning is that "at least one of A or B or C, or any combination thereof" in general. In the case of using expressions such as "at least one of A, B, or C", it will be understood that the meaning is that "at least one of A or B or C, or any combination thereof" in general.

[0041] Due to the scarcity and high price of iridium resources, how to reduce the use amount and improve the specific activity of the catalyst while ensuring the high catalytic performance of iridium has become a hot research issue.

[0042] In the process of implementing the present disclosure, it is found that by introducing transition metals such as ruthenium and tungsten, ternary or multi-component composite oxides can be prepared to improve the performance of iridium-based catalysts. Ruthenium and tungsten can not only regulate the electronic structure of iridium, but also enhance the electrical conductivity and corrosion resistance of the catalyst, thereby further improving the OER catalytic efficiency. At the same time, the introduction of alkali metal nitrate as a fluxing agent and carbon-nitrogen material as a regulating material can promote the formation of oxygen evolution reaction catalysts with nanosheet structure.

[0043] Specifically, according to an embodiment of one aspect of the present disclosure, a preparation method of an oxygen evolution reaction catalyst is provided, comprising: air calcining a mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material to obtain an oxygen evolution reaction catalyst.

[0044] According to the embodiments of the present disclosure, by ternary design of iridium salt, ruthenium salt and tungsten salt, the charge transfer path is optimized, and the electrocatalytic performance and stability are improved. By introducing abundant ruthenium and tungsten, the dependence on scarce and expensive iridium resources is reduced, while maintaining the high catalytic performance of the catalyst. The oxygen evolution reaction catalyst provided by the embodiments of the present disclosure is not only environmentally friendly, but also helps to reduce material costs and improve the sustainable use of resources.

[0045] According to the embodiment of the present disclosure, the microstructure of the oxygen evolution reaction catalyst is optimized by adding the carbon-nitrogen material, which not only effectively prevents the agglomeration of the catalyst, but also effectively regulates the microstructure of the catalyst by consuming local oxygen during air calcination, exposes more active sites, thereby enhancing the electrocatalytic activity of the catalyst; the carbon-nitrogen material can also adjust the valence and stability of the catalyst during sintering, and effectively consumes the local oxygen around the catalyst during air calcination, adjusts the valence of the catalyst, enhances the conductivity and corrosion resistance of the catalyst, and further improves the OER catalytic efficiency.

[0046] According to the embodiment of the present disclosure, the alkali metal nitrate has the functions of auxiliary oxidant and solid-phase catalyst carrier, which helps to form a uniform catalyst structure.

[0047] According to the embodiment of the present disclosure, by air calcination of the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material, during the calcination process, the alkali metal nitrate acts as a fluxing agent, and the carbon-nitrogen material acts as a regulating material, which promotes the formation of the oxygen evolution reaction catalyst with nanosheet structure; and the carbon-nitrogen material can also adjust the valence and stability of the catalyst during sintering, which is conducive to the conductivity of the material. The preparation method provided by the embodiment of the present disclosure simplifies the process, which is conducive to large-scale production and application.

[0048] According to the embodiment of the present disclosure, the present disclosure does not limit the types of iridium salt, ruthenium salt and tungsten salt, and any salt that can obtain metal and its oxide through calcination reaction is within the scope of the present disclosure.

[0049] Preferably, the iridium salt is selected from one or more of chloroiridic acid, chloroiridic acid hydrate and iridium nitrate. Preferably, the ruthenium salt is selected from one or more of trisnitroso ruthenium, hydrated ruthenium trichloride, ruthenium trichloride and dichloride. Preferably, the tungsten salt is selected from one or more of tungsten chloride, oxide or alkali tungsten salt.

[0050] According to the embodiment of the present disclosure, the present disclosure does not limit the types of alkali metal nitrate, and any alkali metal nitrate that can be used as a molten salt method reaction medium is within the scope of the present disclosure.

[0051] Preferably, the alkali metal nitrate is selected from one or more of sodium nitrate, potassium nitrate and lithium nitrate. The preferred alkali metal nitrate has the advantages of high boiling point, low viscosity, high volumetric heat and chemical stability as a molten salt, which ensures the smooth progress of the calcination reaction.

[0052] According to the embodiment of the present disclosure, the present disclosure does not limit the types of carbon-nitrogen material, and any carbon-nitrogen material that can react and consume oxygen during calcination is within the scope of the present disclosure.

[0053] Preferably, the carbon-nitrogen material is selected from one or more of melamine, urea and metal organic framework materials.

[0054] According to embodiments of the present disclosure, the present disclosure is not limited to the preparation method of the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material. The mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material can be obtained by solution mixing or solid mixing. Preferably, the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material is obtained by solution mixing.

[0055] According to embodiments of the present disclosure, the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material is prepared by heating a dispersion liquid containing iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material to evaporate the solvent in the dispersion liquid, thereby obtaining the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material.

[0056] According to embodiments of the present disclosure, by solution mixing, the iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material can be uniformly mixed, which is helpful for the formation of the oxygen evolution reaction catalyst with nanosheet structure.

[0057] According to embodiments of the present disclosure, in the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material, the molar ratio of iridium salt to ruthenium salt is 1:(0.1-10), preferably 1:(1-5). Specifically, in the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material, the molar ratio of iridium salt to ruthenium salt can be 1:0.1, 1:0.2, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0058] According to embodiments of the present disclosure, in the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material, the molar ratio of the sum of iridium salt and ruthenium salt to tungsten salt is 1:(0.01-0.20), preferably 1:(0.05-0.15). Specifically, in the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material, the molar ratio of the sum of iridium salt and ruthenium salt to tungsten salt can be 1:0.01, 1:0.02, 1:0.05, 1:0.10, 1:0.12, 1:0.15, 1:0.18 or 1:0.20.

[0059] According to embodiments of the present disclosure, by precisely controlling the ratio of iridium (Ir), ruthenium (Ru) and tungsten (W), the OER catalytic performance in acidic medium is significantly improved.

[0060] According to an embodiment of the present disclosure, in the mixture of the iridium salt, the ruthenium salt, the tungsten salt, the alkali metal nitrate and the carbon-nitrogen material, the molar ratio of the sum of the iridium salt, the ruthenium salt and the tungsten salt to the alkali metal nitrate is (1-10):100, preferably (4-6):100. Specifically, in the mixture of the iridium salt, the ruthenium salt, the tungsten salt, the alkali metal nitrate and the carbon-nitrogen material, the molar ratio of the sum of the iridium salt, the ruthenium salt and the tungsten salt to the alkali metal nitrate can be 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100 or 10:100.

[0061] According to an embodiment of the present disclosure, the appropriate addition ratio of the alkali metal nitrate can provide the necessary reaction environment and promote the progress of the calcination reaction.

[0062] According to an embodiment of the present disclosure, in the mixture of the iridium salt, the ruthenium salt, the tungsten salt, the alkali metal nitrate and the carbon-nitrogen material, the mass ratio of the carbon-nitrogen material to the alkali metal nitrate is 1:(50-1000), preferably 1:(100-300). Specifically, in the mixture of the iridium salt, the ruthenium salt, the tungsten salt, the alkali metal nitrate and the carbon-nitrogen material, the mass ratio of the carbon-nitrogen material to the alkali metal nitrate can be 1:50, 1:100, 1:200, 1:300, 1:400, 1:500, 1:600, 1:700, 1:800, 1:900 or 1:1000.

[0063] According to an embodiment of the present disclosure, the appropriate addition amount of the carbon-nitrogen material can effectively prevent the agglomeration of the catalyst, and also effectively regulate the microstructure of the catalyst and the valence state of the catalyst by consuming local oxygen during air calcination.

[0064] According to an embodiment of the present disclosure, the calcination temperature is 300-700°C, preferably 350-400°C. Specifically, the calcination temperature can be 300°C, 350°C, 370°C, 400°C, 450°C, 500°C, 600°C or 700°C.

[0065] According to an embodiment of the present disclosure, the calcination time is 1-6h, preferably 2-3h. Specifically, the calcination time can be 1h, 2h, 3h, 4h, 5h or 6h.

[0066] According to an embodiment of the present disclosure, if the calcination temperature is too low, the reaction cannot proceed; if the calcination temperature is too high, it is not conducive to the formation of the nanosheet structure. The appropriate calcination temperature and time can ensure the smooth progress of the calcination reaction and make the prepared oxygen evolution reaction catalyst have a nanosheet structure.

[0067] According to an embodiment of the present disclosure, the heating rate of the calcination is 1 to 10°C / min, preferably 4 to 6°C / min. Specifically, the heating rate of the calcination can be 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min, preferably 5°C / min.

[0068] According to an embodiment of the present disclosure, a dispersion containing iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material is prepared by the following method: mixing a solution containing iridium salt and a solution containing ruthenium salt to obtain a first mixed solution; adding alkali metal nitrate to the first mixed solution to obtain a second mixed solution; adding a solution containing tungsten salt and a carbon-based material to the second mixed solution to obtain a dispersion.

[0069] According to the embodiments of the present disclosure, the dispersion can be made more uniform by mixing in steps, which is beneficial to the formation of the oxygen evolution reaction catalyst having a nanosheet structure.

[0070] According to an embodiment of the present disclosure, in the solution containing an iridium salt, the solution containing a ruthenium salt, and the solution containing a tungsten salt, the solvent can be selected according to the type of metal salt. For example, for WCl6, the solution containing a tungsten salt can be an ethanol solution containing WCl6.

[0071] According to an embodiment of the present disclosure, the concentration of the solution containing the iridium salt is 0.01-1.00 mol / L.

[0072] According to an embodiment of the present disclosure, the concentration of the solution containing the ruthenium salt is 0.02-2.00 mol / L.

[0073] According to an embodiment of the present disclosure, the concentration of the solution containing the tungsten salt is 0.001-0.5 mol / L.

[0074] According to an embodiment of another aspect of the present disclosure, an oxygen evolution reaction catalyst prepared by the above preparation method is provided.

[0075] The oxygen evolution reaction (OER) catalyst provided by the disclosed embodiments has a nanosheet structure, significantly increasing the catalyst's specific surface area and providing more active sites. By adjusting the valence state of the OER catalyst, the catalyst's conductivity and corrosion resistance are enhanced, further improving OER catalytic efficiency. The OER catalyst provided by the disclosed embodiments not only has efficient OER catalytic performance but also exhibits excellent stability, capable of stable operation in acidic media for extended periods.

[0076] According to an embodiment of another aspect of the present disclosure, there is provided an application of the above oxygen evolution reaction catalyst in the field of electrochemical oxygen production.

[0077] The oxygen evolution reaction catalyst provided by the embodiments of the present disclosure is not only suitable for electrochemical oxygen pumps, but also has potential applications in electrochemical devices in other acidic media, such as proton exchange membrane electrolyzers, and the like, thereby providing new possibilities for the development of new energy technologies.

[0078] The technical solutions of the present disclosure are described in detail below by listing a plurality of specific embodiments. It should be noted that the specific embodiments below are only for illustration and do not limit the present disclosure.

[0079] Embodiment 1

[0080] The present embodiment provides a preparation method of an oxygen evolution reaction catalyst, comprising the following steps:

[0081] (1) Preparation of solution

[0082] H2IrCl6·6H2O and RuCl3·xH2O were dissolved in deionized water to obtain 0.1 mol / L iridium salt solution and 0.2 mol / L ruthenium salt solution, respectively.

[0083] WCl6 was dissolved in super-dry ethanol to obtain 0.05 mol / L tungsten salt solution.

[0084] (2) Preparation of dispersion

[0085] 8 mL of iridium salt solution and 5 mL of ruthenium salt solution were mixed and ultrasonically mixed for 30 minutes to obtain a first mixed solution.

[0086] NaNO3 corresponding to a total amount ratio of metal of 1:10 was added to the first mixed solution, and ultrasonication was performed until complete dissolution to obtain a second mixed solution.

[0087] Melamine corresponding to a mass ratio of NaNO3 of 1:100 was added to the second mixed solution as a carbon-nitrogen material and 1 mL of tungsten salt solution, and mixed uniformly to obtain a dispersion.

[0088] (3) Solvent evaporation and grinding

[0089] The dispersion was placed in a vacuum drying box and heated at 60°C until the solvent was completely evaporated to obtain a mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material.

[0090] The mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material was ground into fine powder.

[0091] (4) Calcination

[0092] The powder was loaded into a porcelain boat and placed in a tube furnace, and the temperature was raised to 400°C at a rate of 5°C / min and maintained for 3 hours.

[0093] (5) Post-treatment

[0094] After calcination, the sample was cooled to room temperature and washed with deionized water for several times until the filtrate was colorless.

[0095] The washed sample was dried in a vacuum drying oven at 60°C for 12 hours to obtain an oxygen evolution reaction catalyst.

[0096] Example 2

[0097] The present example provides a method for preparing an oxygen evolution reaction catalyst, comprising the following steps:

[0098] (1) Preparation of solution

[0099] H2IrCl6·6H2O and RuCl3·xH2O were dissolved in deionized water respectively to obtain an iridium salt solution of 0.05 mol / L and a ruthenium salt solution of 0.3 mol / L.

[0100] WCl6 was dissolved in super-dry ethanol to obtain a tungsten salt solution of 0.05 mol / L.

[0101] (2) Preparation of dispersion

[0102] 5 mL of the iridium salt solution and 8 mL of the ruthenium salt solution were mixed and ultrasonically mixed for 30 minutes to obtain a first mixed solution.

[0103] NaNO3 corresponding to a total amount ratio of 1:8 of the metal was added to the first mixed solution, and ultrasonically dissolved until completely dissolved to obtain a second mixed solution.

[0104] Urea corresponding to a mass ratio of 1:200 of NaNO3 was added to the second mixed solution as a carbon-nitrogen material and 1 mL of the tungsten salt solution was added, and mixed uniformly to obtain a dispersion.

[0105] (3) Solvent evaporation and grinding

[0106] The dispersion was placed in a vacuum drying oven and heated to 60°C until the solvent was completely evaporated to obtain a mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material.

[0107] The mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material was ground into fine powder.

[0108] (4) Calcination

[0109] The powder was loaded into a porcelain boat and placed in a tube furnace, and the temperature was raised to 350°C at a rate of 5°C / min and maintained for 2 hours.

[0110] (5) Post-treatment

[0111] After calcination, the sample was cooled to room temperature and washed with deionized water for several times until the filtrate was colorless.

[0112] The washed sample is dried in a vacuum drying oven at 60°C for 12 hours to obtain an oxygen evolution reaction catalyst.

[0113] Example 3

[0114] The present example provides a method for preparing an oxygen evolution reaction catalyst, comprising the following steps:

[0115] (1) Preparation of dispersion liquid

[0116] H2IrCl6·6H2O, RuCl3·xH2O, WCl6, NaNO3 and melamine are added to deionized water, and ultrasonic mixing is performed to obtain a dispersion liquid containing iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material. The addition amount of H2IrCl6·6H2O, RuCl3·xH2O, WCl6, NaNO3 and melamine is the same as that in Example 1.

[0117] The dispersion liquid is subjected to solvent evaporation and grinding, calcination and post-treatment to obtain an oxygen evolution reaction catalyst. For specific steps, refer to Example 1, which will not be repeated here.

[0118] Comparative Example 1

[0119] The present comparative example provides a method for preparing an oxygen evolution reaction catalyst, which refers to Example 1, except that in step (2), only sodium nitrate is added, and no carbon-nitrogen material is added.

[0120] Comparative Example 2

[0121] The present comparative example provides a method for preparing an oxygen evolution reaction catalyst, which refers to Example 1, except that in step (2), only carbon-nitrogen material is added, and no sodium nitrate is added.

[0122] The oxygen evolution reaction catalysts provided in Example 1 and Comparative Example 1 are subjected to scanning electron microscope detection, and the scanning electron microscope images are shown in Figure 1 and Figure 2 As can be seen from the analysis of Figure 1 and Figure 2 , the oxygen evolution reaction catalyst provided in the present example has a smaller size, so the exposed active sites are relatively more, which is more conducive to the reaction.

[0123] The oxygen evolution reaction catalysts provided in Example 1 and Comparative Example 1 are subjected to transmission electron microscope detection, and the transmission electron microscope images are shown in Figure 3 and Figure 4 As can be seen from the analysis of Figure 3 and Figure 4It can be known from the analysis that the oxygen evolution reaction catalyst provided in Embodiment 1 of the present disclosure has a sheet structure with a nanoscale thickness, and the oxygen evolution reaction catalyst particles provided in Comparative Example 1 are obviously thickened and the agglomeration is more obvious.

[0124] The oxygen evolution reaction catalysts provided in Embodiment 1 and Comparative Example 1 were subjected to X-ray diffraction (XRD) detection, and the detection results are shown in FIG. 2. Figure 5 Figure 5 It can be known from the analysis that the oxygen evolution reaction catalyst prepared without adding carbon-nitrogen material (Comparative Example 1) is obviously a mixed oxide peak shape, and the metal valence of the oxygen evolution reaction catalyst prepared by adding carbon-nitrogen material (Embodiment 1) is obviously different, and a pure metal diffraction peak appears at more than forty degrees, which indicates that there is a certain low-valence metal (for example, zero-valence metal) in the catalyst.

[0125] The oxygen evolution reaction (OER) tests were performed on the oxygen evolution reaction catalysts provided in Embodiment 1, Comparative Examples 1 and 2. The test conditions are as follows:

[0126] Electrolyte: The electrolyte used is a 1.0 mol / L H2SO4 solution to ensure that the test is performed in an acidic environment;

[0127] Electrode configuration: A three-electrode system is used, including a working electrode (catalyst), a counter electrode (platinum electrode) and a reference electrode (Ag / AgCl).

[0128] Polarization curve measurement: Linear sweep voltammetry (LSV) is used for polarization curve measurement, and the scan rate is 1-5 mV / s to ensure that the electrode surface is basically in a steady state.

[0129] The polarization curves obtained by the test are shown in FIG. 3. Figure 6 Figure 6 It can be known from the analysis that the overpotential of Embodiment 1 of the present disclosure at 10 mA / cm 2 is optimal.

[0130] The oxygen evolution reaction catalysts provided in Embodiment 1 and Comparative Example 1 were coated on a proton exchange membrane (acidic) using a conventional membrane electrode process as an anode of an oxygen pump, and a standard platinum carbon catalyst was used as a cathode for comparison, and the reaction area was 4 cm x 4 cm. The membrane electrode coated with the catalyst was assembled into a current collector to form a complete oxygen pump system. Among them,

[0131] The anode reaction is:

[0132]

[0133] The cathode reaction is:

[0134]

[0135] ​​The oxygen pump was tested for performance in air, and the oxygen evolution effect, concentration and stability at different voltages were recorded. The oxygen evolution effect is shown in Figure 7 The oxygen evolution test results are shown in Figure 8 The oxygen evolution test results are shown in Figure 8 It can be seen from the analysis that the oxygen pump assembled using the oxygen evolution reaction catalyst provided in Embodiment 1 can be stably operated for more than 120 hours at a voltage of 1.5 V, showing excellent catalytic performance and stability. The oxygen pump assembled using the oxygen evolution reaction catalyst provided in Comparative Example 1 has a significantly increased voltage after 50 hours, and cannot effectively perform the catalytic reaction any more.

[0136] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above-described specific embodiments are merely examples of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for preparing an oxygen evolution reaction catalyst, characterized in that: include: calcining a mixture of iridium salt, ruthenium salt, tungsten salt, flux alkali metal nitrate and carbon-nitrogen material in air to obtain an oxygen evolution reaction catalyst; The mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material is prepared by the following method: heating a dispersion containing iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material until the solvent in the dispersion evaporates to obtain the mixture of iridium salt, ruthenium salt, tungsten salt, alkali metal nitrate and carbon-nitrogen material; In the mixture of the iridium salt, the ruthenium salt, the tungsten salt, the alkali metal nitrate and the carbon-nitrogen material: the molar ratio of the iridium salt to the ruthenium salt is 1:(0.1-10); the molar ratio of the sum of the iridium salt and the ruthenium salt to the tungsten salt is 1:(0.01-0.20); the molar ratio of the sum of the iridium salt, the ruthenium salt and the tungsten salt to the alkali metal nitrate is (1-10):100; the mass ratio of the carbon-nitrogen material to the alkali metal nitrate is 1:(50-1000); The calcination temperature is 300-700°C; the calcination time is 1-6 hours; The carbon-nitrogen material is selected from one or more of melamine and urea.

2. The preparation method according to claim 1, characterized in that The heating rate of the calcination is 1-10°C / min; The calcination temperature is 350-400°C.

3. The preparation method according to claim 1, characterized in that The alkali metal nitrate is selected from one or more of sodium nitrate, potassium nitrate and lithium nitrate; The iridium salt is selected from one or more of chloroiridic acid, chloroiridic acid hydrate and iridium nitrate; The ruthenium salt is selected from one or more of trinitronitrosylruthenium, hydrated ruthenium trichloride, ruthenium trichloride and ruthenium dichloride; The tungsten salt is selected from one or more of tungsten chloride, oxide or alkali metal tungsten salt.

4. The preparation method according to claim 1, characterized in that The dispersion containing iridium salt, ruthenium salt, tungsten salt, nitrate of alkali metal and carbon nitrogen material is prepared by the following method: mixing a solution containing an iridium salt and a solution containing a ruthenium salt to obtain a first mixed solution; adding the alkali metal nitrate to the first mixed solution to obtain a second mixed solution; A solution containing tungsten salt and the carbon-nitrogen material are added to the second mixed liquid to obtain the dispersion.

5. The preparation method according to claim 4, characterized in that The concentration of the solution containing the iridium salt is 0.01 to 1.00 mol / L; The concentration of the solution containing ruthenium salt is 0.02-2.00 mol / L; The concentration of the solution containing the tungsten salt is 0.001-0.5 mol / L.

6. An oxygen evolution reaction catalyst obtained by the preparation method according to any one of claims 1 to 5, characterized in that: The oxygen evolution reaction catalyst is a nanosheet structure.

7. Use of the oxygen evolution reaction catalyst according to claim 6 in the field of electrochemical oxygen production.

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