An alloy catalyst for fuel cells and a method for preparing the same

Abstract

The application provides a preparation method of an alloy catalyst for a fuel cell, comprising the following steps: mixing an acid containing a heteroatom with carbon carrier powder, stirring, filtering, cleaning and drying to obtain a modified carbon carrier; mixing the modified carbon carrier with a solvent to form a carbon carrier solution mixture; adding a platinum source compound and an M metal source compound, reacting with a reducing agent, filtering, cleaning and drying to obtain a first semi-finished product; placing the first semi-finished product in an atmosphere furnace or a tube furnace, passing a reducing gas, heating to T1 temperature, reacting for a certain time, then heating to T2 temperature, reacting for a certain time, cooling to room temperature, and obtaining a second semi-finished product; placing the second semi-finished product in an acid solution with a certain concentration, reacting at a certain temperature for a certain time, filtering, cleaning and drying to obtain a third semi-finished product; and heating and cooling the third semi-finished product to obtain the alloy catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy fuel cells, and in particular relates to an alloy catalyst for fuel cells and a preparation method thereof. Background Art

[0002] Currently, proton exchange membrane fuel cells primarily use platinum-based precious metal catalysts, the most typical being platinum-supported carbon (Pt / C) catalysts. However, Pt-based catalysts require a high Pt metal loading, which can lead to poor durability and low mass activity. To address these issues, Pt-M / C alloy catalysts (M = Ni, Co, Fe, Cu, Zn, Cr) have been developed in recent years. These catalysts offer significant improvements in electrical performance compared to traditional catalysts, and their application as fuel cell cathode catalysts, in particular, holds great promise. To further enhance the performance of Pt-M / C alloy catalysts, a high-temperature alloying treatment is required at the end of the preparation process. This treatment aims to systematically rearrange the different metal atoms in the catalyst, forming an ordered alloy structure. This improves the catalyst's stability and durability, extending its lifespan, and minimizing the dissolution of different metals from the Pt-M / C alloy catalyst during long-term fuel cell operation, which can lead to performance degradation.

[0003] However, typical high-temperature alloying treatments involve calcining the catalyst semi-finished product under an inert gas atmosphere at elevated temperatures exceeding 500°C. The biggest challenge with this process is that as the high-temperature treatment time increases, the catalyst nanoparticles agglomerate, increasing their size, reducing electrochemical activity, and ultimately degrading fuel cell performance.

[0004] In order to reduce the problem of agglomeration of catalyst particles during high-temperature alloying, researchers have tried various methods, including doping the catalyst carrier with heteroatoms (such as N, S, Mn, P, and B), and using the strong interaction between platinum-heteroatom-carbon carrier to anchor the catalyst Pt-M alloy particles and inhibit agglomeration during alloying. This method requires mixing the heteroatom-containing compound with the carrier and calcining it at high temperature to form bonds between the heteroatoms and carbon atoms. However, high-temperature calcination can also have negative effects, such as the loss of active sites on the carrier and the decomposition of some functional groups on the carrier surface, which makes it impossible to evenly disperse the catalyst when using this type of carrier for liquid-phase synthesis, and destroys the pore structure of the carrier. Ultimately, during the synthesis of catalysts using this type of carrier, it is difficult for the catalyst particles to be evenly dispersed on the carrier, and the performance of the prepared catalyst samples deteriorates. Summary of the Invention

[0005] In view of the above, the present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention provides an alloy catalyst for fuel cells and a method for preparing the same. The alloy catalyst for fuel cells provided by the present invention has a novel and unique structure and exhibits excellent catalytic activity and stability. Furthermore, the preparation method is simple in process flow and suitable for large-scale industrial production.

[0006] To this end, in the first aspect, an embodiment of the present invention provides a method for preparing an alloy catalyst for a fuel cell, the preparation method comprising: adding an acid containing a heteroatom to water to form an acid solution, adding carbon carrier powder, mixing and stirring at a certain temperature for a certain time to dope the surface of the carbon carrier with acid radical groups containing heteroatoms, and then filtering, washing and drying to obtain a modified carbon carrier; mixing the modified carbon carrier with a solvent to form a carbon carrier solution mixture; adding a platinum source compound, an M metal source compound, a reducing agent and a carbon carrier solution mixture in a certain proportion to a reactor, reacting at a certain temperature for a certain time, and then After filtering, washing and drying, a primary semi-finished product is obtained; the primary semi-finished product is placed in an atmosphere furnace, a tubular furnace or the like, a reducing gas is introduced, the temperature is raised to T1 and reacted for a certain time, the temperature is then raised to T2 and reacted for a certain time, and the product is cooled to room temperature to obtain a secondary semi-finished product; the secondary semi-finished product is placed in an acid solution of a certain concentration, the product is reacted at a certain temperature for a certain time, the product is filtered, washed and dried to obtain a tertiary semi-finished product; the tertiary semi-finished product is placed in an atmosphere furnace, a tubular furnace or the like, a reducing gas is introduced, the temperature is raised to T3 and reacted for a certain time, the product is cooled to room temperature and taken out to obtain the alloy catalyst.

[0007] Preferably, the acid containing heteroatoms is one or more of sulfuric acid, sulfurous acid, nitric acid, nitrous acid, boric acid, phosphoric acid, phosphorous acid, and permanganic acid; the concentration of the acid solution is 0.1-20 mol / L; the mixing method is one or more of ball milling, sand milling, high-speed dispersion, ultrasonic dispersion, etc.; the stirring temperature is 20-100° C.; the stirring time is 30-300 min; and the drying method is vacuum drying.

[0008] Preferably, the ratio of heteroatom element mass to carbon element mass in the modified carbon support material is 0.01-5%; and the solvent is one or more of ethylene glycol, water, oleylamine, diphenyl ether, dibenzyl ether, o-dichlorobenzene, chloroform, and tetralin.

[0009] Preferably, the platinum source compound is one or more of chloroplatinic acid, platinum acetylacetonate, potassium chloroplatinate, and platinum chloride; the M metal source compound is one or more of cobalt acetate, cobalt hydroxide, cobalt chloride, cobalt nitrate, cobalt sulfate, basic cobalt carbonate, cobalt acetylacetonate III, cobalt acetylacetonate II, copper acetate, copper hydroxide, copper chloride, copper nitrate, copper sulfate, copper acetylacetonate, ferric acetate, ferric hydroxide, ferric chloride, ferric acetylacetonate, nickel acetylacetonate, nickel hydroxide, nickel chloride, zinc nitrate, zinc chloride, zinc acetylacetonate, and chromium chloride; the reducing agent is one or more of sodium hypophosphite, formaldehyde, sodium borohydride, tetradecanediol, dimethylaminoborane, and borane-tert-butylamine complex; the reaction temperature is 90-300° C., and the reaction time is 30-1200 min.

[0010] Preferably, the molar ratio of the platinum element in the platinum source compound to the M element in the M metal source compound is (1:1)-(5:1); the mass ratio of the platinum element in the platinum source compound to the carbon support is (5:95)-(7:3).

[0011] Preferably, the reducing gas is hydrogen, acetylene, or a mixture of hydrogen and inert gas with a certain concentration, the T1 temperature is 100-450° C., and the T1 temperature reaction time is 30-1200 min.

[0012] Preferably, the T2 temperature is 450-1000° C., and the T2 temperature reaction time is 30-1200 min.

[0013] Preferably, the acid solution is one or more of perchloric acid, nitric acid, sulfuric acid, and acetic acid, the acid solution concentration is 0.01-0.5 mol / L, the reaction temperature is 40-100° C., the reaction time is 60-1200 min, the cleaning agent is water, and the drying method is vacuum drying.

[0014] Preferably, the reducing gas is hydrogen, acetylene, and a mixture of hydrogen and inert gas of a certain concentration; the T3 temperature is 200-400° C., the reaction time is 30-1200 min, and the mass fraction of heteroatomic elements in the alloy catalyst is 0.005-2%.

[0015] In a second aspect, an embodiment of the present invention provides an alloy catalyst for a fuel cell prepared using the method described in the first aspect, wherein the alloy catalyst includes a complex formed by platinum and a transition metal element, and the complex is supported on a carbon material; the transition metal is one or more of nickel, cobalt, iron, copper, chromium and zinc.

[0016] The preparation method provided by the present invention utilizes the acid containing heteroatom groups to directly treat the carbon support during the preparation process, and the heteroatom is doped in a group manner. At the same time, during the acid treatment process, the number of active sites on the carbon support surface is not only not lost, but the active sites are increased, making it easier to disperse the support of the catalyst prepared in the later stage, and the loading is more uniform. In addition, for the problem of particle agglomeration caused by general alloying process treatment, the preparation method provided by the present invention is that during the preparation process, the heteroatom-doped support is first heat-treated at a temperature lower than the alloying temperature under a reducing gas atmosphere, so that the heteroatom groups on the support are decomposed to form a heteroatom-doped support, and then the temperature is increased to a temperature higher than the alloying temperature, and a high-temperature alloying treatment is performed, using Pt-heteroatom-carbon support interaction to suppress the agglomeration problem during the alloying process, thereby effectively improving the catalytic activity and stability of the Pt-M / C alloy catalyst. At the same time, the preparation method process is simple, suitable for application in large-scale industrial production, and the preparation method process is simple, suitable for application in large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a method for preparing an alloy catalyst for a fuel cell provided in an embodiment of the present invention;

[0018] Figure 2 TEM image of the alloy catalyst prepared in Example 1 of the present invention;

[0019] Figure 3 TEM image of the alloy catalyst prepared in Example 6 of the present invention;

[0020] Figure 4 TEM image of the alloy catalyst prepared in Comparative Example 1 of the present invention;

[0021] Figure 5 This is a TEM image of the alloy catalyst prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0022] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0023] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will appreciate the reusability of other processes and / or the use of other materials.

[0024] The present invention aims to provide an alloy catalyst for fuel cells and a method for preparing the same. The alloy catalyst comprises a complex of platinum and a transition metal element, the complex being supported on a carbon material; the transition metal being one or more of nickel, cobalt, iron, copper, chromium, and zinc. Specifically, the alloy catalyst is a Pt-M / C alloy catalyst, where M can be one or more of nickel, cobalt, iron, copper, chromium, and zinc. The preparation method comprises first modifying a carbon support with an acid containing a heteroatom (wherein the heteroatom-acid may be: S-sulfuric acid, sulfurous acid; N-nitric acid, nitrous acid; B-boric acid; P-phosphoric acid, phosphorous acid; Mn-permanganic acid) to increase the number of active sites on the carbon support surface for binding to catalyst particles, while retaining the heteroatoms within the carbon support in the form of groups, without undergoing high-temperature calcination. After filtering and cleaning the modified carbon support, a platinum source, an M metal source compound, a reducing agent, and a solvent are added to conduct a synthesis reaction, thereby obtaining a catalyst semi-finished product with uniformly bonded and distributed particles and containing heteroatoms. After drying, the semi-finished catalyst is heat-treated in a reducing atmosphere below the alloying temperature, then heated to above the alloying temperature for alloying. Finally, the alloyed semi-finished catalyst is treated with acid and then with high temperature to obtain a heteroatom-doped Pt-M / C alloy catalyst.

[0025] The preparation method provided by the present invention utilizes an acid containing a heteroatom group to directly treat a carbon support during the preparation process, and the heteroatom is doped in a group manner. At the same time, during the acid treatment process, the number of active sites on the carbon support surface is not only not lost, but the active sites are increased, making it easier to disperse the support of the catalyst prepared in the later stage, and the loading is more uniform. In addition, for the problem of particle agglomeration caused by general alloying process treatment, the preparation method provided by the present invention is due to the heteroatom-doped support in the preparation process. In a reducing gas atmosphere, the first heat treatment is performed below the alloying temperature so that the heteroatom groups on the support are decomposed to form a heteroatom-doped support, and then the temperature is increased to above the alloying temperature, and a high-temperature alloying treatment is performed. The Pt-heteroatom-carbon support interaction is utilized to suppress the agglomeration problem during the alloying process, thereby effectively improving the catalytic activity and stability of the Pt-M / C alloy catalyst. At the same time, the preparation method process is simple and suitable for application in large-scale industrial production.

[0026] The present invention provides a method for preparing an alloy catalyst for a fuel cell. Figure 1 As shown, the preparation method comprises the following steps:

[0027] Step S1: adding a heteroatom-containing acid to water to form an acid solution, adding carbon support powder, mixing, and stirring at a certain temperature for a certain time to dope the surface of the carbon support with heteroatom-containing acid groups, and then filtering, washing, and drying to obtain a modified carbon support;

[0028] The heteroatom-containing acid may be one or more of sulfuric acid, sulfurous acid, nitric acid, nitrous acid, boric acid, phosphoric acid, phosphorous acid, and permanganic acid; the concentration of the acid solution is 0.1-20 mol / L; the mixing method is one or more of ball milling, sand milling, high-speed dispersion, ultrasonic dispersion, etc.; the stirring temperature is 20-100° C.; the stirring time is 30-300 min; and the drying method is vacuum drying.

[0029] Step S2: mixing the modified carbon support with a solvent to form a carbon support solution mixture;

[0030] Wherein, the solvent and the mixing method are one or more of ball milling, sand milling, high-speed dispersion, ultrasonic dispersion, etc.

[0031] Step S3: adding a mixture of a platinum source compound, an M metal source compound, a reducing agent, and a carbon support solution into a reactor in a certain proportion, reacting at a certain temperature for a certain time, filtering, washing, and drying to obtain a primary semi-finished product;

[0032] Wherein, the platinum source compound can be one or more of chloroplatinic acid, platinum acetylacetonate, potassium chloroplatinate, and platinum chloride; the M metal source compound can be one or more of cobalt acetate, cobalt hydroxide, cobalt chloride, cobalt nitrate, cobalt sulfate, basic cobalt carbonate, cobalt acetylacetonate III, cobalt acetylacetonate II, copper acetate, copper hydroxide, copper chloride, copper nitrate, copper sulfate, copper acetylacetonate, ferric acetate, ferric hydroxide, ferric chloride, ferric acetylacetonate, nickel acetylacetonate, nickel hydroxide, nickel chloride, zinc nitrate, zinc chloride, zinc acetylacetonate, and chromium chloride; the reducing agent is one or more of sodium hypophosphite, formaldehyde, sodium borohydride, tetradecanediol, dimethylaminoborane, and borane-tert-butylamine complex; the reaction temperature is 90-300°C, and the reaction time is 30-1200min.

[0033] In addition, in this step, after filtering the above-mentioned reactants, they can be washed with a liquid compatible with the solvent, such as water, ethanol, n-propanol, isopropanol, n-hexane, and chloroform, to remove excess solvent, platinum source compound, M metal source compound, reducing agent and other impurities; the drying method can be vacuum drying.

[0034] Step S4: placing the primary semi-finished product in an atmosphere furnace, a tubular furnace, or the like, introducing a reducing gas, heating the product to a temperature T1 for a certain reaction time, then heating the product to a temperature T2 for a certain reaction time, and cooling the product to room temperature to obtain a secondary semi-finished product;

[0035] Among them, the reducing gas can be hydrogen, acetylene gas and a certain concentration of hydrogen-inert gas mixture; the T1 temperature can be 100-450°C, and the T1 temperature reaction time can be 30-1200min; the T2 temperature can be 500-1000°C, and the T2 temperature reaction time can be 30-1200min.

[0036] In the present embodiment, at temperature T1, the platinum source, heteroatoms in the form of groups, and the carbon support in the primary semi-finished product form a Pt-heteroatom-carbon support interaction. At temperature T2, the Pt-M in the primary semi-finished product undergoes a regular rearrangement, forming an ordered alloy structure. It is understood that temperature T1 is above the decomposition temperature of the corresponding heteroatom groups but below the alloying treatment temperature; temperature T2 is above the alloying treatment temperature.

[0037] Step S5: placing the secondary semi-finished product into an acid solution of a certain concentration, reacting at a certain temperature for a certain time, filtering, washing, and drying to obtain a tertiary semi-finished product;

[0038] The acid solution is one or more of perchloric acid, nitric acid, sulfuric acid, and acetic acid, the acid solution concentration is 0.01-0.5 mol / L, the reaction temperature is 40-100° C., the reaction time is 60-1200 min, the cleaning agent is water, and the drying method is vacuum drying.

[0039] In this step, the secondary semi-finished product is placed in the acid solution to wash away surface impurities and M metal, so that more Pt metal is on the surface, thereby further improving the catalyst performance, and is washed with water to remove excess acid.

[0040] Step S6: placing the three semi-finished products in an atmosphere furnace, a tubular furnace or the like, introducing a reducing gas, heating to T3, reacting for a certain period of time, cooling to room temperature and taking out to obtain the alloy catalyst.

[0041] The reducing gas may be hydrogen, acetylene, or a mixture of hydrogen and inert gas of a certain concentration; the T3 temperature may be 200-400°C, the reaction time may be 30-1200 min, and the mass fraction of heteroatomic elements in the alloy catalyst may be 0.005-2%.

[0042] In this step, the T3 temperature is lower than the T2 temperature. This is because the Pt-M ratio of the surface layer of the three semi-finished products changes after acid treatment in step S5. In order to make the arrangement of metal atoms on the surface of the catalyst after acid treatment more regular and stable, heat treatment is performed. At the same time, in order not to cause particle agglomeration, the T3 temperature is lower than the T2 temperature.

[0043] The preparation method provided by the present invention utilizes an acid containing a heteroatom group to directly treat a carbon support during the preparation process, and the heteroatom is doped in a group manner. At the same time, during the acid treatment process, the number of active sites on the carbon support surface is not only not lost, but the active sites are increased, making it easier to disperse the support of the catalyst prepared in the later stage, and the loading is more uniform. In addition, for the problem of particle agglomeration caused by general alloying process treatment, the preparation method provided by the present invention is due to the heteroatom-doped support in the preparation process. In a reducing gas atmosphere, the first heat treatment is performed below the alloying temperature so that the heteroatom groups on the support are decomposed to form a heteroatom-doped support, and then the temperature is increased to above the alloying temperature, and a high-temperature alloying treatment is performed. The Pt-heteroatom-carbon support interaction is utilized to suppress the agglomeration problem during the alloying process, thereby effectively improving the catalytic activity and stability of the Pt-M / C alloy catalyst. At the same time, the preparation method process is simple and suitable for application in large-scale industrial production.

[0044] The following examples are further listed to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description herein, and are not limited to the specific numerical values ​​exemplified below.

[0045] Modified carrier preparation:

[0046] Modified carrier 1:

[0047] 20 g of carbon powder XC-72 (Cabot Corporation, USA) was added to 3 L of a pre-prepared 10 mol / L sulfuric acid solution and placed in a jacketed glass reactor. The carbon support acid solution was heated to 70°C by oil bath circulation heating; then, a high-speed disperser was used at a speed of 10,000 rpm for 250 minutes; the mixture was filtered and repeatedly washed with deionized water until the pH value of the liquid reached 7; the dispersion was filtered and vacuum dried at 100 degrees for 24 hours to obtain a modified carbon support 1.

[0048] Modified carrier 2:

[0049] 20 g of carbon black EC300J (Lion Corporation, Japan) was added to 1.8 L of a pre-prepared 20 mol / L phosphoric acid solution and dispersed at 3000 rpm for 30 min using a high-speed disperser; filtered and repeatedly washed with deionized water until the pH value of the liquid reached 7; the dispersion was filtered and vacuum dried at 100°C for 24 hours to obtain a modified carbon support 2.

[0050] Modified carrier 3:

[0051] 24 g of acetylene black (Nippon Denki Kagaku Kogyo Co., Ltd.) was added to 4 L of a pre-prepared 10 mol / L nitric acid solution and dispersed using a 5 mm ball mill at 600 rpm for 120 min; filtered and repeatedly washed with deionized water until the liquid pH reached 7; the dispersion was filtered and vacuum dried at 100°C for 24 hours to obtain a modified carbon support 3.

[0052] Modified carrier 4:

[0053] 30 g of carbon nanotubes MWNT-10 (Shenzhen Nanoport Co., Ltd.) were added to 25 L of a pre-prepared 0.1 mol / L permanganate solution and dispersed in a nano sand mill at 3900 rpm for 70 min. The mixture was filtered and repeatedly washed with deionized water until the pH value of the liquid reached 7. The dispersion was filtered and vacuum dried at 100°C for 24 h to obtain a modified carbon support 4.

[0054] Modified carrier 5:

[0055] 30 g of graphitized carbon powder SD600 (Shenzhen BTR New Energy Materials Co., Ltd.) was added to 18 L of a pre-prepared 2 mol / L permanganate solution and ultrasonically dispersed at 60 Hz for 300 min at 20°C using an ultrasonic grinder; the mixture was filtered and repeatedly washed with deionized water until the pH value of the liquid reached 7; the dispersion was filtered and vacuum dried at 100°C for 24 hours to obtain a modified carbon support 5.

[0056] Modified carrier 6:

[0057] 20 g of carbon powder XC-72 (Cabot Corporation, USA) was added to 10 L of a pre-prepared sulfuric acid solution with a concentration of 20 mol / L, placed in a jacketed glass reactor, and the carbon support acid solution was heated to 100°C by oil bath circulation heating; then, a high-speed disperser was used at a speed of 15,000 rpm for 300 minutes; filtered, and repeatedly washed with deionized water until the pH value of the liquid reached 7; the dispersion was filtered and vacuum dried at 100°C for 24 hours to obtain a modified carbon support 6.

[0058] Example 1

[0059] This embodiment provides an alloy catalyst for a fuel cell and a preparation method thereof, comprising the following steps:

[0060] (1) 16 g of the modified carbon support 1 was added to 2 L of ethylene glycol and dispersed using a 5 mm ball mill at 400 rpm for 2 h;

[0061] (2) The dispersion was taken out and placed in a 5 L reactor. 14.9 g of platinum acetylacetonate, 3.6 g of basic cobalt carbonate, and 1.2 g of sodium hypophosphite were added, and the mixture was heated to 175° C. and reacted for 200 min. The mixture was cooled to room temperature, the reaction liquid was taken out, and the mixture was repeatedly washed with a large amount of water until the pH value was 7. The mixture was filtered and vacuum dried at 100° C. for 24 hours to obtain a semi-finished product.

[0062] (3) The semi-finished product obtained in the previous step is placed in a high-temperature atmosphere furnace, heated to 340°C in a 5% concentration of hydrogen and nitrogen mixed gas atmosphere for 120 minutes, then further heated to 700°C for 60 minutes, and naturally cooled to obtain a secondary semi-finished product;

[0063] (4) The secondary semi-finished product obtained in the previous step was placed in a pre-prepared 0.1 mol / L perchloric acid aqueous solution, ultrasonicated for 30 minutes, heated to 80°C, treated for 600 minutes, filtered, repeatedly washed with water until the pH value was 7, filtered and dried to obtain a tertiary semi-finished product;

[0064] (5) The three semi-finished products obtained in the previous step were placed in a high-temperature atmosphere furnace, heated to 300° C. and treated for 60 min in a 5% concentration of hydrogen and nitrogen mixed gas atmosphere to obtain an alloy catalyst.

[0065] Figure 2 Shown is a TEM image of the alloy catalyst prepared in this example.

[0066] Example 2

[0067] The preparation process of the alloy catalyst for fuel cells in this embodiment is similar to that in Example 1, with the only difference being that the modified carbon support 1 in Example 1 is replaced by the modified carbon support 2, and the other steps are the same as those in Example 1.

[0068] Example 3

[0069] The preparation process of the alloy catalyst for fuel cells in this embodiment is similar to that in Example 1, with the only difference being that the modified carbon support 1 in Example 1 is replaced by the modified carbon support 3, and the other steps are the same as those in Example 1.

[0070] Example 4

[0071] The preparation process of the alloy catalyst for fuel cells in this embodiment is similar to that in Example 1, with the only difference being that the modified carbon support 1 in Example 1 is replaced by the modified carbon support 4, and the other steps are the same as those in Example 1.

[0072] Example 5

[0073] The preparation process of the alloy catalyst for fuel cells in this embodiment is similar to that in Example 1, with the only difference being that the modified carbon support 1 in Example 1 is replaced by the modified carbon support 5, and the other steps are the same as those in Example 1.

[0074] Example 6

[0075] The preparation process of the alloy catalyst for fuel cells in this embodiment is similar to that in Example 1, with the only difference being that the modified carbon support 1 in Example 1 is replaced by the modified carbon support 6, and the other steps are the same as those in Example 1.

[0076] Figure 3 Shown is a TEM image of the alloy catalyst prepared in this example.

[0077] Example 7

[0078] This embodiment provides an alloy catalyst for a fuel cell and a preparation method thereof, comprising the following steps:

[0079] (1) 16 g of the modified carbon support 1 was added to 2 L of diphenyl ether and dispersed using a sand mill at 2400 rpm for 4 hours;

[0080] (2) The dispersion was taken out and placed in a 5 L reactor, and 8 g of platinum acetylacetonate, 2.7 g of nickel acetylacetonate and 1.2 g of tert-butylamine borane complex were added, and the mixture was heated to 220 ° C for reaction for 1200 min, cooled to room temperature, and the reaction liquid was taken out. The solution was repeatedly washed with a large amount of ethanol until the conductivity was less than 20 μs / cm, and then repeatedly washed with a large amount of water until the pH value was 7, filtered, and vacuum dried at 100 ° C for 24 hours to obtain a semi-finished product;

[0081] (3) placing the primary semi-finished product obtained in the previous step into a high-temperature atmosphere furnace, heating it to 450°C at a rate of 4°C per minute in an acetylene gas atmosphere for 1200 min, then heating it to 700°C for 90 min, and cooling it naturally to obtain a secondary semi-finished product;

[0082] (4) The secondary semi-finished product obtained in the previous step was placed in a pre-prepared 0.5 mol / L nitric acid aqueous solution, sonicated for 30 minutes, heated to 70°C, treated for 720 minutes, filtered, and repeatedly washed with water until the pH value reached 7, filtered and dried to obtain a tertiary semi-finished product;

[0083] (5) The three semi-finished products obtained in the previous step were placed in a high-temperature atmosphere furnace, and heated to 300 degrees at a rate of 4 degrees per minute under an acetylene gas atmosphere for 60 minutes to obtain an alloy catalyst.

[0084] Example 8

[0085] This embodiment provides an alloy catalyst for a fuel cell and a preparation method thereof, comprising the following steps:

[0086] (1) 16 g of the modified carbon support 1 was added to 2 L of diphenyl ether and dispersed using a sand mill at 2400 rpm for 4 hours;

[0087] (2) The dispersion was taken out and placed in a 5 L reactor, and 8 g of chloroplatinic acid, 2.1 g of copper chloride and 1.2 g of borane tert-butylamine complex were added, and the mixture was heated to 300 ° C for 1200 min. The mixture was cooled to room temperature, and the reaction liquid was taken out and repeatedly washed with a large amount of n-hexane: ethanol mixture with a volume ratio of 1:1 until the solution conductivity was less than 20 μs / cm. The mixture was then repeatedly washed with a large amount of water until the pH value was 7, filtered, and vacuum dried at 100 ° C for 24 hours to obtain a semi-finished product;

[0088] (3) placing the primary semi-finished product obtained in the previous step into a high-temperature atmosphere furnace, heating it to 100°C at a rate of 4°C per minute in an acetylene gas atmosphere for 30 minutes, then heating it to 1000°C for 90 minutes, and cooling it naturally to obtain a secondary semi-finished product;

[0089] (4) The secondary semi-finished product obtained in the previous step was placed in a pre-prepared 0.5 mol / L nitric acid aqueous solution, sonicated for 30 minutes, heated to 70°C, treated for 720 minutes, filtered, repeatedly washed with water until the pH value was 7, filtered and dried to obtain a tertiary semi-finished product;

[0090] (5) The three semi-finished products obtained in the previous step were placed in a high-temperature atmosphere furnace, and heated to 300°C at a rate of 4 degrees per minute under an acetylene gas atmosphere for 60 minutes to obtain an alloy catalyst.

[0091] Example 9

[0092] This embodiment provides an alloy catalyst for a fuel cell and a preparation method thereof, comprising the following steps:

[0093] (1) 16 g of the modified carbon support 1 was added to 2 L of pure water and dispersed using a sand mill at 2400 rpm for 4 hours;

[0094] (2) The dispersion was taken out and placed in a 5 L reactor. 8 g of potassium chloroplatinate, 2.1 g of ferric nitrate, and 8 g of formaldehyde solution were added. The mixture was heated to 90° C. and reacted for 1200 min. The mixture was cooled to room temperature. The reaction liquid was taken out and then repeatedly washed with a large amount of water until the pH value was 7. The mixture was filtered and vacuum dried at 100° C. for 24 hours to obtain a semi-finished product.

[0095] (3) placing the primary semi-finished product obtained in the previous step into a high-temperature atmosphere furnace, heating it at a rate of 4 degrees per minute to 100 degrees Celsius for 30 minutes in an acetylene gas atmosphere, then heating it to 1000 degrees Celsius for 90 minutes, and then cooling it naturally to obtain a secondary semi-finished product;

[0096] (4) The secondary semi-finished product obtained in the previous step was placed in a pre-prepared 0.5 mol / L perchloric acid aqueous solution, ultrasonicated for 30 minutes, heated to 80°C, treated for 1200 minutes, filtered, repeatedly washed with water until the pH value was 7, filtered and dried to obtain a tertiary semi-finished product;

[0097] (5) The three semi-finished products obtained in the previous step were placed in a high-temperature atmosphere furnace, and heated to 300°C at a rate of 4 degrees per minute under an acetylene gas atmosphere for 60 minutes to obtain an alloy catalyst.

[0098] Example 10

[0099] This embodiment provides an alloy catalyst for a fuel cell and a preparation method thereof, comprising the following steps:

[0100] (1) 16 g of the modified carbon support 1 was added to 2 L of oleylamine and dispersed using a sand mill at 2400 rpm for 4 hours;

[0101] (2) The dispersion was taken out and placed in a 5 L reactor. 8 g of potassium chloroplatinate, 1.8 g of chromium chloride, and 8 g of formaldehyde solution were added. The mixture was heated to 290° C. for reaction for 1200 min. The mixture was cooled to room temperature. The reaction liquid was taken out and repeatedly washed with a large amount of ethanol until the solution conductivity was less than 20 μS / cm. The solution was then repeatedly washed with a large amount of water until the pH value was 7. The mixture was filtered and vacuum dried at 100° C. for 24 hours to obtain a semi-finished product.

[0102] (3) placing the primary semi-finished product obtained in the previous step into a high-temperature atmosphere furnace, heating it to 450°C at a rate of 4°C per minute in an acetylene gas atmosphere for 1200 min, then heating it to 1000°C for 1200 min, and cooling it naturally to obtain a secondary semi-finished product;

[0103] (4) The secondary semi-finished product obtained in the previous step was placed in a pre-prepared 0.5 mol / L nitric acid aqueous solution, sonicated for 30 minutes, heated to 70°C, treated for 720 minutes, filtered, repeatedly washed with water until the pH value was 7, filtered and dried to obtain a tertiary semi-finished product;

[0104] (5) The three semi-finished products obtained in the previous step were placed in a high-temperature atmosphere furnace, and heated to 300°C at a rate of 4 degrees per minute under an acetylene gas atmosphere for 60 minutes to obtain an alloy catalyst.

[0105] Example 11

[0106] This embodiment provides an alloy catalyst for a fuel cell and a preparation method thereof, comprising the following steps:

[0107] (1) 16 g of the modified carbon support 1 was added to 2 L of ethylene glycol and dispersed using a sand mill at 2400 rpm for 4 hours;

[0108] (2) The dispersion was taken out and placed in a 5 L reactor. 8 g of potassium chloroplatinate, 1.8 g of zinc acetylacetonate, and 2.4 g of sodium hypophosphite were added. The mixture was heated to 190° C. and reacted for 1200 min. The mixture was cooled to room temperature. The reaction liquid was taken out and then repeatedly washed with a large amount of water until the pH value reached 7. The mixture was filtered and vacuum dried at 100° C. for 24 hours to obtain a semi-finished product.

[0109] (3) placing the primary semi-finished product obtained in the previous step into a high-temperature atmosphere furnace, heating it to 400°C at a rate of 4°C per minute in an acetylene gas atmosphere for 100 min, then heating it to 500°C for 180 min, and cooling it naturally to obtain a secondary semi-finished product;

[0110] (4) The secondary semi-finished product obtained in the previous step was placed in a pre-prepared 0.5 mol / L sulfuric acid aqueous solution, ultrasonicated for 30 minutes, heated to 70°C, treated for 720 minutes, filtered, repeatedly washed with water until the pH value was 7, filtered and dried to obtain a tertiary semi-finished product.

[0111] (5) The three semi-finished products obtained in the previous step were placed in a high-temperature atmosphere furnace, and heated to 300° C. at a rate of 4 degrees per minute in a 5% hydrogen and nitrogen mixed gas atmosphere for 60 minutes to obtain an alloy catalyst.

[0112] Example 12

[0113] (1) 16 g of the modified carbon support 1 was added to 2 L of ethylene glycol and dispersed using a sand mill at 2400 rpm for 4 hours;

[0114] (2) The dispersion was taken out and placed in a 5 L reactor, and 8 g of potassium chloroplatinate, 1.75 g of nickel acetylacetonate, 0.9 g of zinc acetylacetonate, and 2.4 g of sodium hypophosphite were added. The mixture was heated to 190° C. and reacted for 1200 min. The mixture was cooled to room temperature, and the reaction liquid was taken out. The mixture was then repeatedly washed with a large amount of water until the pH value was 7, filtered, and vacuum dried at 100° C. for 24 hours to obtain a semi-finished product.

[0115] (3) placing the primary semi-finished product obtained in the previous step into a high-temperature atmosphere furnace, heating it to 400°C at a rate of 4°C per minute in an acetylene gas atmosphere for 100 min, then heating it to 500°C for 180 min, and cooling it naturally to obtain a secondary semi-finished product;

[0116] (4) The secondary semi-finished product obtained in the previous step was placed in a pre-prepared 0.5 mol / L sulfuric acid aqueous solution, ultrasonicated for 30 minutes, heated to 70°C, treated for 720 minutes, filtered, repeatedly washed with water until the pH value was 7, filtered and dried to obtain a tertiary semi-finished product;

[0117] (5) The three semi-finished products obtained in the previous step were placed in a high-temperature atmosphere furnace, and heated to 300° C. at a rate of 4 degrees per minute in a 5% hydrogen and nitrogen mixed gas atmosphere for 60 minutes to obtain an alloy catalyst.

[0118] Comparative Example 1

[0119] The preparation process of the alloy catalyst for fuel cells in this embodiment refers to that in Example 1, with the only difference being that the modified carbon support 1 in Example 1 is replaced with carbon powder XC-72, and the other steps are the same as in Example 1.

[0120] Figure 4 Shown is a TEM image of the alloy catalyst prepared in this example.

[0121] Comparative Example 2

[0122] The preparation process of the alloy catalyst for fuel cells in this embodiment refers to that in Example 1, with the only difference being that the modified carbon support 1 in Example 1 is replaced with carbon black EC300, and the other steps are the same as in Example 1.

[0123] Figure 5 Shown is a TEM image of the alloy catalyst prepared in this example.

[0124] Comparative Example 3

[0125] Pt-Co / C catalyst product TEC36F52 from Tanaka Precious Metals Co., Ltd. of Japan.

[0126] Note: Comparative Examples 1 and 2 use unmodified carbon supports. Although unmodified carbon supports do not contain heteroatoms and heat treatment at temperature T1 is ineffective, in order to verify the effect of the technical solution of the present invention, the heat treatment method still adopts the same treatment process as in the embodiment.

[0127] The products prepared in Examples 1-12 and Comparative Examples 1-3 were subjected to performance tests, including the following tests:

[0128] Electrochemically active area, output voltage in polarization curve, ratio of electrochemically active area after 30,000 cycles to initial electrochemically active area, and 1A / cm in polarization curve after 30,000 cycles 2 Output voltage and initial 1A / cm 2 The specific test method for the output voltage ratio refers to GBT20042.5-2009 "Proton Exchange Membrane Fuel Cell Part 5: Membrane Electrode Test Method" and T / CAAMTB 12-2020 "Proton Exchange Membrane Fuel Cell Membrane Electrode Test Method". The element content test uses a scanning electron microscope energy dispersive spectrometer (SEM-EDS) to test the content of heteroatom elements, carbon elements, oxygen elements, platinum elements, and M elements in the modified carbon support material. The molar ratio of different elements can be simply calculated by measuring the corresponding element content and the corresponding element molecular weight using SEM-EDS. Scanning electron microscope energy dispersive spectrometer (SEM-EDS) is a relatively common test method for quantitatively testing element content. Catalyst particle morphology and particle size were measured by taking photos of catalyst particles using a transmission electron microscope (TEM). The average particle size of the Pt-M particles in the catalyst and the D90 particle size (the particle size corresponding to the cumulative particle size distribution number reaching 90%) were statistically calculated using particle size statistics software based on the particle photos. The specific test results are shown in Table 1.

[0129] Table 1. Test items and test results of Examples 1-12 and Comparative Examples 1-3

[0130]

[0131] The alloy catalysts prepared in Example 1, Example 6 and Comparative Example 1 and Comparative Example 2 were tested by TEM. The results are as follows: Figure 2 、 3 , 4, and 5. By comparison, it is found that the alloy catalyst prepared by the preparation method provided by the present invention can effectively inhibit the agglomeration of nanoparticles during the alloying process, maintain the uniformity of particle size, and effectively improve the activity of the alloy catalyst.

[0132] In addition, according to Table 1, it can be seen that the alloy catalyst particles obtained in Example 1 and Example 6 of the present invention are uniform in size and are evenly distributed, and no particle agglomeration phenomenon is found. Wherein Example 6 of the present invention is because acid concentration is higher, temperature is higher, dispersion linear velocity is larger, and dispersion time is longer in the modified carbon support preparation process, so that the heteroatom element mass ratio in the carrier is higher. In the subsequent alloy catalyst prepared, heteroatom element mass is higher, stronger Pt-heteroatom-carbon support interaction can be formed, and particle agglomeration in the alloying process can be more effectively suppressed, so that the alloy catalyst particles are distributed more evenly on the carbon support, and are more difficult to agglomerate after alloying treatment, and the particle size of the alloy catalyst prepared is finally made smaller, more uniform, and electrochemical active area is higher, and output voltage is higher under equal current density, and output voltage retention rate is higher under electrochemical active area and equal current density after 30000 cycles. And the alloy catalyst particles obtained in Comparative Examples 1 and 2 are unevenly distributed, and obvious agglomeration occurs in the alloying process, and final catalyst performance is all relatively poor.

[0133] In addition, according to Table 1, it can be seen that the alloy catalysts for fuel cells prepared in Examples 1-12 of the present invention have a higher electrochemical active area and a higher output voltage at the same current density than the alloy catalysts prepared in Comparative Example 1 and Comparative Example 2. This shows that the alloy catalyst prepared by the preparation method provided by the present invention has a greater output power.

[0134] In addition, it can be seen from Table 1 that the alloy catalysts for fuel cells prepared in Examples 1-12 of the present invention have higher electrochemical active areas and output voltage retention rates at the same current density after 30,000 cycles than the alloy catalysts prepared in Comparative Example 1 and Comparative Example 2 and the catalyst of Comparative Example 3. This shows that the alloy catalysts prepared using the preparation method provided by the present invention have better durability.

[0135] At the same time, it can be seen from Example 12 of the present invention that the preparation method provided by the present invention can still achieve good results when preparing a ternary alloy Pt-Ni-Zn / C catalyst in which the M metals are Ni and Zn, indicating that the preparation method provided by the present invention is also suitable for the preparation of a multi-element Pt-M / C catalyst.

[0136] In the description of this specification, the reference terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0137] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for preparing an alloy catalyst for a fuel cell, characterized in that: The preparation method comprises: Step S1: adding a heteroatom-containing acid to water to form an acid solution, adding carbon support powder, mixing, and stirring at a certain temperature for a certain time to dope the surface of the carbon support with heteroatom-containing acid groups, and then filtering, washing, and drying to obtain a modified carbon support; Step S2: mixing the modified carbon support with a solvent to form a carbon support solution mixture; Step S3: adding a mixture of a platinum source compound, an M metal source compound, a reducing agent, and a carbon support solution into a reactor in a certain proportion, reacting at a certain temperature for a certain time, filtering, washing, and drying to obtain a primary semi-finished product; Step S4: placing the primary semi-finished product in an atmosphere furnace or a tubular furnace, introducing a reducing gas, heating it to temperature T1 for a certain reaction time, then heating it to temperature T2 for a certain reaction time, and cooling it to room temperature to obtain a secondary semi-finished product; Step S5: placing the secondary semi-finished product into an acid solution of a certain concentration, reacting at a certain temperature for a certain time, filtering, washing, and drying to obtain a tertiary semi-finished product; Step S6: The three semi-finished products are placed in an atmosphere furnace or a tubular furnace, a reducing gas is introduced, the temperature is raised to T3, the reaction time is set, and the reaction is cooled to room temperature and removed to obtain the alloy catalyst; In step S4, the reducing gas is hydrogen, acetylene or a mixture of hydrogen and inert gas with a certain concentration, the T1 temperature is 100-450°C, and the T1 temperature reaction time is 30-1200 minutes; in step S4, the T2 temperature is 450-1000°C, and the T2 temperature reaction time is 30-1200 minutes.

2. The method for preparing an alloy catalyst for a fuel cell according to claim 1, wherein: In step S1, the acid containing heteroatoms is one or more of sulfuric acid, sulfurous acid, nitric acid, nitrous acid, boric acid, phosphoric acid, phosphorous acid, and permanganic acid; the concentration of the acid solution is 0.1-20 mol / L; the mixing method is one or more of ball milling, sand milling, high-speed dispersion, and ultrasonic dispersion; the stirring temperature is 20-100° C.; and the stirring time is 30-300 min; and the drying method is vacuum drying.

3. The method for preparing an alloy catalyst for a fuel cell according to claim 1, wherein: In step S2, the ratio of heteroatom element mass to carbon element mass in the modified carbon support material is 0.01-5%; and the solvent is one or more of ethylene glycol, water, oleylamine, diphenyl ether, dibenzyl ether, o-dichlorobenzene, chloroform, and tetralin.

4. The method for preparing an alloy catalyst for a fuel cell according to claim 1, wherein: In step S3, the platinum source compound is one or more of chloroplatinic acid, platinum acetylacetonate, potassium chloroplatinate, and platinum chloride; the M metal source compound is one or more of cobalt acetate, cobalt hydroxide, cobalt chloride, cobalt nitrate, cobalt sulfate, basic cobalt carbonate, cobalt acetylacetonate III, cobalt acetylacetonate II, copper acetate, copper hydroxide, copper chloride, copper nitrate, copper sulfate, copper acetylacetonate, ferric acetate, ferric hydroxide, ferric chloride, ferric acetylacetonate, nickel acetylacetonate, nickel hydroxide, nickel chloride, zinc nitrate, zinc chloride, zinc acetylacetonate, and chromium chloride; the reducing agent is one or more of sodium hypophosphite, formaldehyde, sodium borohydride, tetradecanediol, dimethylaminoborane, and borane-tert-butylamine complex; the reaction temperature is 90-300° C., and the reaction time is 30-1200 min.

5. The method for preparing an alloy catalyst for a fuel cell according to claim 1, wherein: In step S3, the molar ratio of the platinum element in the platinum source compound to the M element in the M metal source compound is (1:1)-(5:1); the mass ratio of the platinum element in the platinum source compound to the carbon support is (5:95)-(7:3).

6. The method for preparing an alloy catalyst for a fuel cell according to claim 1, wherein: In step S5, the acid solution is one or more of perchloric acid, nitric acid, sulfuric acid, and acetic acid, the acid solution concentration is 0.01-0.5 mol / L, the reaction temperature is 40-100° C., the reaction time is 60-1200 min, the cleaning agent is water, and the drying method is vacuum drying.

7. The method for preparing an alloy catalyst for a fuel cell according to claim 1, wherein: In step S6, the reducing gas is hydrogen, acetylene or a mixture of hydrogen and inert gas of a certain concentration; the T3 temperature is 200-400°C, the reaction time is 30-1200 min, and the mass fraction of heteroatom elements in the alloy catalyst is 0.005-2%.

8. The alloy catalyst for fuel cells prepared by the method according to any one of claims 1 to 7, characterized in that: The alloy catalyst includes a complex formed by platinum and a transition metal element, and the complex is supported on a carbon material; the transition metal is one or more of nickel, cobalt, iron, copper, chromium and zinc.

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