Nitrogen-doped platinum alloy catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of fuel cell catalysts, and provides a nitrogen-doped platinum alloy catalyst and a preparation method and application thereof. The nitrogen-doped platinum alloy catalyst comprises an active component and a conductive carrier, wherein the active component comprises a transition metal crystal nucleus and a nitrogen-doped platinum shell layer coating the surface of the transition metal crystal nucleus. The nitrogen-doped platinum alloy catalyst provided by the invention has a unique core-shell structure, and transition metal can be protected from being eroded by acid, so that the durability of the catalyst is improved; the preparation process is simple, a surfactant and a complex solvent system are not needed, the cost is low, and the method can be used for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell catalysts, and more specifically, to a nitrogen-doped platinum alloy catalyst and a preparation method and application thereof. Background Art

[0002] Energy shortage and environmental pollution have become increasingly serious problems in today's world, so fuel cells that efficiently use clean and renewable fuels to generate electricity are attracting more and more attention. A fuel cell is a battery device that uses a catalyst to convert chemical energy into electrical energy. Unlike ordinary batteries, as long as there is a continuous supply of fuel and oxidant, it can discharge continuously without repeated charging. Proton exchange membrane fuel cells (PEMFC) are a new energy power generation device with broader application prospects. Due to its low operating temperature and small size, it is suitable as a power source for electric vehicles. It is recognized by the industry as the future development direction of electric vehicle batteries and has become a hot spot for fuel cell research in countries around the world.

[0003] In practical applications, carbon materials loaded with highly dispersed platinum metal (such as Pt / C catalyst) and its alloy materials have long been very effective catalysts for oxygen reduction reaction and hydrogen oxidation reaction in commercial PEMFC. However, considering the small reserves and high price of Pt, as well as the sluggish ORR kinetics of Pt-based catalysts, it is hoped that nitrogen atoms with stronger electronegativity than carbon atoms will be introduced into carbon materials, so that the electrons around carbon atoms will be transferred to nitrogen atoms, thereby improving the ability of carbon atoms to adsorb oxygen and promoting the ORR kinetic process. Therefore, nitrogen atoms are usually doped into carbon materials to obtain better electrocatalytic performance and anti-poisoning ability.

[0004] For example, the patent CN115133051A applied by Beijing Yihuatong Technology Co., Ltd. indicates that the ultra-low platinum fuel cell catalyst prepared by it belongs to the field of fuel cell technology, and solves the problems of high cost, low platinum utilization rate and easy corrosion of carbon carriers of existing fuel cell catalysts. However, when the fuel cell catalyst prepared by this method works under acidic conditions, the transition metal therein will gradually dissolve, thereby causing the catalyst to be deactivated. The patent CN115799531A of the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences indicates that the method uses the metal nitrogen carbon obtained by high-temperature carbonization of the imidazole metal organic framework as a carrier, and the precursor of platinum and the metal nitrogen carbon are ultrasonically dispersed, dried, heat-treated in a reducing atmosphere and combined with an acid pickling and etching process to obtain a catalyst. The nitrogen-doped carbon carrier can inhibit the agglomeration of nanoparticles during high-temperature calcination, which is conducive to obtaining a catalyst with small and uniformly dispersed metal nanoparticles. However, when the catalyst prepared in this way works under acidic conditions, there is also the problem of gradual dissolution of the transition metal, and the metal organic framework preparation method is complicated and costly, and the operation of first preparing the nitrogen-doped carrier and then loading platinum is more complicated, which is not conducive to scale-up production. Summary of the invention

[0005] The purpose of the present invention is to provide a nitrogen-doped platinum alloy catalyst and a preparation method and application thereof, so as to solve the technical problems in the prior art that the preparation method of the nitrogen-doped catalyst is complicated and the transition metal in the catalyst is easily soluble in acid.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a nitrogen-doped platinum alloy catalyst, comprising an active component and a conductive carrier, wherein the active component comprises a transition metal crystal core and a nitrogen-doped platinum shell layer coated on the surface of the transition metal crystal core.

[0008] In the nitrogen-doped platinum alloy catalyst provided by the present invention, the transition metal crystal core is wrapped by the nitrogen-doped platinum shell layer, which can effectively avoid the risk of the transition metal being corroded in an acidic environment.

[0009] According to some embodiments of the present invention, the transition metal includes at least one of manganese, iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, osmium, and iridium, preferably at least one of cobalt, nickel, copper, ruthenium, rhodium, and iridium.

[0010] According to some embodiments of the present invention, the molar ratio of platinum to transition metal is 1:(0.2-5), preferably 1:(0.5-4), and more preferably 1:(2-3.5).

[0011] According to some embodiments of the present invention, the ratio of the sum of the masses of the platinum and the transition metal to the mass of the conductive carrier is 1:(0.05-9), preferably 1:(1-4).

[0012] According to some embodiments of the present invention, the doping amount of nitrogen is 1 to 15 wt %.

[0013] According to some embodiments of the present invention, the electrochemical mass activity of the catalyst is >0.33 A / mgPt.

[0014] According to some embodiments of the present invention, the electrochemical mass activity of the catalyst is >0.52 A / mgPt.

[0015] According to some embodiments of the present invention, the catalyst is saturated with 0.1 mol·L -1 In the hypochlorous acid solution, the voltage was 200 mV·s in the range of 0.6 to 1.0 V. -1 The half-wave potential drop amplitude before and after the accelerated aging test of 5000 cyclic voltammetry scans at a scan rate of 0.09 V is less than 0.09 V. The nitrogen-doped platinum alloy catalyst provided by the present invention has good corrosion resistance and durability.

[0016] According to some embodiments of the present invention, the catalyst is saturated with 0.1 mol·L -1 In the hypochlorous acid solution, the voltage was 200 mV·s in the range of 0.6 to 1.0 V. -1 The half-wave potential drop before and after the accelerated aging test of 5000 cyclic voltammetry scans was ≤0.07V.

[0017] In a second aspect, the present invention provides a method for preparing a nitrogen-doped platinum alloy catalyst, comprising:

[0018] S1. Adding a transition metal precursor to a solvent containing a controlled coordination agent, mixing and dissolving; then dropping an alkaline solution; then adding a platinum precursor and mixing and dissolving; finally adding a nitrogen-containing additive and mixing and dissolving to obtain a mixed solution;

[0019] S2. mixing the mixed solution with a conductive carrier, and hydrothermally crystallizing to obtain the catalyst;

[0020] Optionally, the method further comprises S3. calcining the catalyst under a hydrogen environment and / or subjecting the catalyst to an acid treatment.

[0021] The preparation method of the catalyst provided by the present invention forms a complex with a platinum precursor by using a controlled coordination reagent, so that the reduction rates of the platinum precursor and the transition metal precursor are different during the reduction process by a solvent, and the transition metal salt is preferentially reduced to form a nanocrystalline core, and then a platinum shell layer is controlled to be generated on the surface of the crystal core to protect the crystal core and prevent the transition metal in the crystal core from being corroded.

[0022] The present invention adopts a one-pot hydrothermal method to produce the nitrogen-doped platinum alloy catalyst, the preparation method is simple, and no surfactant and complex solvent system are required.

[0023] The nitrogen-doped platinum alloy catalyst prepared by the above method includes a conductive carrier and an active component loaded on the conductive carrier, and the active component includes a transition metal nucleus and a nitrogen-doped platinum shell coated on the surface of the transition metal nucleus. Since the catalyst is prepared by a one-pot method, nitrogen is inevitably doped into the conductive carrier while doping the platinum shell. The introduction of nitrogen into the catalyst can, on the one hand, change the local electron density of the conductive carrier, trigger the redistribution of electrons between the carrier and the active component, thereby realizing the regulation of the electronic structure of the active component; on the other hand, it provides lone pairs of electrons for forming a hydrogen bond network, thereby regulating the hydrophilicity of the catalyst and improving the dispersibility of the catalyst in the reaction system, and the rich nitrogen species can provide a stable anchoring point for the active component, thereby improving the dispersibility and stability of the active component on the carbon carrier. In addition, some nitrogen species provide alkaline sites for the catalyst, which can participate in the reaction as a solid base, enriching the application range of the nitrogen-doped platinum alloy catalyst.

[0024] According to some embodiments of the present invention, the catalyst is obtained after the hydrothermal crystallization is subjected to solvent removal (washing with ultrapure water), washing (washing with an organic solvent), and (standing) drying.

[0025] According to some embodiments of the present invention, the transition metal precursor includes at least one of transition metal chlorides, bromides, nitrates, sulfates, acetates, and acetylacetonates, preferably at least one of transition metal chlorides, nitrates, acetates, and acetylacetonates.

[0026] According to some embodiments of the present invention, the transition metal is selected from at least one of manganese, iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, osmium and iridium, preferably at least one of cobalt, nickel, copper, ruthenium, rhodium and iridium.

[0027] According to some embodiments of the present invention, the controlled coordination agent includes at least one of benzoic acid, 4'-aminomethylfluorescein (AMF), polyvinylpyrrolidone (PVP), cyclohexylamine, and aniline.

[0028] According to some embodiments of the present invention, the solvent includes at least one of water, polyols, benzyl alcohol, and N,N-dimethylformamide (DMF), preferably a polyol, and more preferably at least one selected from ethylene glycol, glycerol, diethylene glycol, and triethylene glycol.

[0029] In the present invention, polyols are used as solvents, which are more conducive to controlling the reduction rate of platinum precursors and transition metal precursors by solvents compared to other solvents, so that the transition metal salts are preferentially reduced to form nanocrystalline cores, and then the reduction process of controlling the formation of a platinum shell on the surface of the crystal core is more controllable, which can better protect the crystal core and prevent the transition metal in the crystal core from being corroded.

[0030] According to some embodiments of the present invention, the alkaline solution includes at least one of aqueous ammonia, ammonium chloride solution and sodium hydroxide solution.

[0031] According to some embodiments of the present invention, the platinum precursor includes at least one of chloroplatinic acid, potassium chloroplatinate, potassium chloroplatinite, platinum acetylacetonate, platinum acetate, tetraamine platinum dichloride and tetraamine platinum nitrate, preferably at least one of potassium chloroplatinite, platinum acetylacetonate and platinum acetate.

[0032] According to some embodiments of the present invention, the nitrogen-containing auxiliary agent includes at least one of melamine, urea, aniline and ammonium carbonate.

[0033] According to some embodiments of the present invention, the conductive carrier includes at least one of a conductive carbon carrier, a metal oxide and a metal carbide, preferably at least one of carbon black XC-72 and carbon black BP2000.

[0034] According to some embodiments of the present invention, the ratio of the sum of the masses of the platinum precursor and the transition metal precursor to the mass of the coordination control reagent is 1:(1-9), preferably 1:(3-7), and more preferably 1:(4-6).

[0035] According to some embodiments of the present invention, the molar ratio of platinum contained in the platinum precursor to the transition metal contained in the transition metal precursor is 1:(0.2-5), preferably 1:(0.5-4), and more preferably 1:(2-3.5).

[0036] According to some embodiments of the present invention, the ratio of the sum of the mass of platinum contained in the platinum precursor and the transition metal contained in the transition metal precursor to the mass of the conductive carrier is 1:(0.05-9), preferably 1:(1-4).

[0037] According to some embodiments of the present invention, the mass ratio of the nitrogen-containing auxiliary agent to the conductive carrier is (1-4):1.

[0038] According to some embodiments of the present invention, in step S1, an alkaline solution is added dropwise until the pH value of the system is 5 to 10, preferably 7 to 10, and more preferably 7.5 to 9.7.

[0039] According to some embodiments of the present invention, the hydrothermal crystallization temperature is 150-200° C. and the time is 6-24 hours.

[0040] According to some embodiments of the present invention, the hydrogen environment is a mixture of hydrogen and argon; preferably, the concentration of the hydrogen is 1-6%.

[0041] According to some embodiments of the present invention, the calcination temperature is 100 to 800° C., preferably 300 to 600° C.; and the calcination time is 1 to 6 hours.

[0042] According to some embodiments of the present invention, the acid treatment includes impregnating the catalyst with an acid and then performing a heat treatment.

[0043] According to some embodiments of the present invention, the acid comprises at least one of dilute hydrochloric acid, dilute sulfuric acid, acetic acid and citric acid solution.

[0044] In the present invention, the concentration of the dilute hydrochloric acid, dilute sulfuric acid, and citric acid solution used can be a common concentration that is conducive to acid treatment, such as 1 mol / L.

[0045] According to some embodiments of the present invention, the temperature of the heating treatment is 40 to 80° C., and the time is 0.5 to 3 hours.

[0046] In a third aspect, the present invention provides a nitrogen-doped platinum alloy catalyst prepared by the preparation method described in the second aspect.

[0047] In a fourth aspect, the present invention provides use of the nitrogen-doped platinum alloy catalyst described in the first aspect or the nitrogen-doped platinum alloy catalyst described in the third aspect in a fuel cell system, especially in a proton membrane exchange fuel cell system.

[0048] The beneficial effects of the present invention are at least:

[0049] (1) The nitrogen-doped platinum alloy catalyst provided by the present invention has a low platinum content and a unique core-shell structure, which can protect the transition metal from being corroded by acid, thereby improving the durability of the catalyst.

[0050] (2) The nitrogen-doped platinum alloy catalyst provided by the present invention can improve the electrochemical activity of the catalyst through nitrogen doping. On the other hand, nitrogen can inhibit the agglomeration of nanoparticles during high-temperature calcination, which is conducive to obtaining a catalyst with small and uniformly dispersed metal nanoparticles.

[0051] (3) The present invention adopts a one-pot hydrothermal method to produce nitrogen-doped platinum alloy catalysts. The preparation method is simple in process, does not require the use of surfactants and complex solvent systems, is low in cost, and can be used for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is an XPS photo of the catalyst of Example 1;

[0053] Figure 2 Comparison image of CV curves of the catalysts of Example 1 and Comparative Example 1

[0054] Figure 3 This is the ORR reaction polarization curve of Example 1 before and after aging.

[0055] Figure 4 HAADF-STEM image of the catalyst of Example 1 and EDS element mapping images of Pt and Ni in the catalyst. DETAILED DESCRIPTION

[0056] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this patent in detail and do not limit the scope of protection of the present invention in any way.

[0057] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples, etc., can all be purchased on the market or can be obtained by existing methods; the reagent amounts, unless otherwise specified, are the reagent amounts used in conventional experimental operations; the experimental methods, unless otherwise specified, are all conventional methods.

[0058] In each embodiment and comparative example of the present invention, each performance data is tested according to the following test method:

[0059] (1) Electrochemical performance of the catalyst: A standard three-electrode system was used, with a platinum sheet as the counter electrode, a silver chloride electrode as the reference electrode, and a 0.1 M HClO4 electrolyte. Cyclic voltammetry (CV) was performed at 50 mVs in a N2-saturated electrolyte. -1 The oxygen reduction reaction was carried out in an oxygen-saturated electrolyte with an electrode rotation speed of 1600 rpm and a scan rate of 5 mVs -1 .

[0060] (2) Catalyst aging resistance: The catalyst was tested in an O2-saturated 0.1 M HClO4 electrolyte at 200 mV·s in the range of 0.6 to 1.0 V. -1 The cyclic voltammetry scans were performed 5000 times at a scan rate as an accelerated aging test, and the aging degree of the catalyst was determined by comparing the difference in half-wave potential before and after aging.

[0061] Example 1

[0062] The preparation method of the catalyst comprises:

[0063] First, dissolve 250 mg of benzoic acid in 15 mL of ethylene glycol; then add 35.8 mg of nickel chloride hexahydrate to the solution, stir until completely dissolved, slowly add ammonia water and control the pH value of the solution to 8; then add 21 mg of potassium chloroplatinite and stir for 30 minutes to obtain a clear solution; then dissolve 200 mg of urea in the solution; finally, add 63 mg of carbon black XC-72 to the clear solution and stir until uniform to obtain a mixed solution.

[0064] The mixed solution was added to a 200 mL hydrothermal autoclave, reacted at 180°C and normal pressure for 12 hours, ultrapure water was added to the cooled solution and centrifuged for washing, the above steps were repeated several times, and then added to ethanol for ultrasonic dispersion and dried to obtain a catalyst. The obtained catalyst was then calcined at 600°C for 4 hours in a tubular furnace in a 5% hydrogen and argon mixed gas atmosphere, and finally soaked in acetic acid in a centrifuge tube and placed in a water bath and heated at 60°C for 1 hour.

[0065] The sample catalyst was analyzed by XPS. Figure 1 As shown, there are three characteristic peaks of Pt, C and O in the catalyst. In addition, the high-resolution N1s signal at ~400.1eV proves the existence of N element, proving that the N element in urea has been successfully doped into the platinum alloy catalyst.

[0066] The CV curves of Example 1 and Comparative Example 1 are as follows: Figure 2 As shown. Figure 2 It can be found that the nitrogen-doped platinum alloy catalyst of this embodiment has a higher electrochemical active surface area and stronger unit activity than the commercial platinum carbon catalyst, indicating that nitrogen doping can achieve the regulation of the electronic structure of the active component on the one hand; on the other hand, it provides lone pairs of electrons for forming a hydrogen bond network, thereby regulating the hydrophilicity of the catalyst and improving the dispersion of the catalyst in the reaction system; and the rich nitrogen species can provide a stable anchoring point for the active component, thereby improving the dispersion and stability of the active component on the carbon carrier and improving the electrochemical performance of the catalyst. The electrochemical surface area (ECSA) of the two catalysts was calculated by double-layer correction of the charge integral on the adsorption peak (0.02-0.4V) of the CV curve, and the electrochemical mass activity of the catalyst was further calculated, and the results are shown in Table 1.

[0067] The ORR reaction polarization curves of the nitrogen-doped platinum alloy catalyst before and after aging are shown in the figure below: Figure 3 The test was carried out in an oxygen atmosphere at room temperature with a concentration of 0.1 mol·L -1Perchloric acid was used as the electrolyte, and the ORR reaction polarization curve of the catalyst was tested by a rotating disk electrode electrochemical workstation at a constant potential of 0.1VvsRHE and a disk speed of 1600rpm. The difference data of the half-wave potential before and after aging are shown in Table 1. Figure 3 From the data in the table, it can be found that the addition of nitrogen and the use of a dual alloy core-shell structure greatly improve the electrochemical durability of the catalyst. This is because nitrogen doping can inhibit the agglomeration of nanoparticles during high-temperature calcination, thereby improving the corrosion resistance of the catalyst.

[0068] The HAADF-STEM image of the nitrogen-doped platinum alloy catalyst of this embodiment and the EDS element mapping image of Pt and Ni in the catalyst are shown in Figure 4 .from Figure 4 As can be seen in (a), in the nitrogen-doped platinum alloy catalyst of this embodiment, more nanoparticles are gathered in the core center compared to the edge shell. Figure 4 From (b) to (d), it can be found that Ni is mainly concentrated in the inner layer of the alloy and is surrounded by a shell layer composed of Pt. Figure 4 It can be found that in the synthesis of nitrogen-doped platinum alloy catalysts, due to the addition of the coordination control reagent benzoic acid, the reduction rates of the two metal precursors by ethylene glycol are significantly different. The Ni precursor is first reduced to form Ni polyhedral nanoparticles, and then the Pt precursor is reduced and coated around the Ni nanoparticles to form a core-shell structured alloy.

[0069] Example 2

[0070] The preparation method of the catalyst comprises:

[0071] First, dissolve 240 mg of benzoic acid in 15 mL of ethylene glycol; then add 34.5 mg of nickel chloride hexahydrate to the solution, stir until completely dissolved, slowly add ammonia water and control the pH value of the solution to 8; then add 19 mg of potassium chloroplatinite and stir for 30 minutes to obtain a clear solution; then dissolve 180 mg of urea in the solution; finally, add 60 mg of carbon black BP2000 to the clear solution and stir until uniform to obtain a mixed solution.

[0072] The mixed solution was added to a 200 mL hydrothermal autoclave, reacted at 160°C and normal pressure for 18 hours, ultrapure water was added to the cooled solution and centrifuged for washing, the above steps were repeated several times, and then added to ethanol for ultrasonic dispersion and dried to obtain a catalyst. The obtained catalyst was then calcined at 500°C for 5 hours in a tubular furnace in a 5% hydrogen and argon mixed gas atmosphere, and finally soaked in acetic acid in a centrifuge tube and placed in a water bath and heated at 50°C for 2 hours.

[0073] Example 3

[0074] The preparation method of the catalyst is the same as that of Example 1, except that 35.8 mg of nickel chloride hexahydrate is replaced by 35.8 mg of cobalt chloride hexahydrate.

[0075] Example 4

[0076] The preparation method of the catalyst is similar to that of Example 1, except that 35.8 mg of nickel chloride hexahydrate is replaced by 26.7 mg of nickel acetate.

[0077] Example 5

[0078] The preparation method of the catalyst is similar to that of Example 1, except that 35.8 mg of nickel chloride hexahydrate is replaced by 38.7 mg of nickel acetylacetonate.

[0079] Example 6

[0080] The preparation method of the catalyst is similar to that of Example 1, except that 35.8 mg of nickel chloride hexahydrate is replaced by 27.5 mg of nickel nitrate.

[0081] Example 7

[0082] The preparation method of the catalyst is similar to that of Example 1, except that the pH value of the solution is controlled at 9 instead of 8.

[0083] Example 8

[0084] The preparation method of the catalyst is similar to that of Example 1, except that 15 mL of ethylene glycol is replaced by 15 mL of benzyl alcohol.

[0085] Example 9

[0086] The preparation method of the catalyst is the same as that of Example 1, except that 15 mL of ethylene glycol is replaced by 15 mL of N,N-dimethylformamide.

[0087] Example 10

[0088] The preparation method of the catalyst comprises:

[0089] First, dissolve 250 mg of benzoic acid in 15 mL of ethylene glycol; then add 35.8 mg of nickel chloride hexahydrate to the solution, stir until completely dissolved, slowly add ammonia water and control the pH value of the solution to 8; then add 21 mg of potassium chloroplatinite and stir for 30 minutes to obtain a clear solution; then dissolve 200 mg of urea in the solution; finally, add 63 mg of carbon black XC-72 to the clear solution and stir until uniform to obtain a mixed solution.

[0090] The mixed solution was added into a 200 mL hydrothermal autoclave and reacted at 180°C and normal pressure for 12 h. Ultrapure water was added into the cooled solution and washed by centrifugation. The above steps were repeated several times and then added into ethanol for ultrasonic dispersion and dried to obtain a catalyst.

[0091] Embodiment 11

[0092] The preparation method of the catalyst is the same as that of Example 1, except that the catalyst is not soaked with acetic acid in the centrifuge tube and is not heated in a water bath at 60° C. for 1 h.

[0093] Example 12

[0094] The preparation method of the catalyst is similar to that of Example 1, except that the high-temperature calcination is carried out in an air atmosphere.

[0095] Embodiment 13

[0096] The preparation method of the catalyst is similar to that of Example 1, except that benzoic acid is replaced with an equal amount of 4'-aminomethylfluorescein.

[0097] Embodiment 14

[0098] The preparation method of the catalyst is similar to that of Example 1, except that benzoic acid is replaced with an equal mass of polyvinyl pyrrolidone.

[0099] Embodiment 15

[0100] The preparation method of the catalyst is as in Example 1, except that benzoic acid is replaced with an equal mass of cyclohexylamine.

[0101] Example 16

[0102] The preparation method of the catalyst is similar to that of Example 1, except that benzoic acid is replaced with an equal mass of aniline.

[0103] Comparative Example 1

[0104] A commercial platinum-carbon catalyst with a platinum content of 20% (a commercial product of Premetek with the brand name P10A200) was used without any special treatment. Ethanol and nafion membrane solution were added to form a 2 mg / mL slurry, and its electrochemical performance was tested after ultrasonic dispersion.

[0105] Comparative Example 2

[0106] The preparation method of the catalyst is the same as that of Example 1, except that 200 mg of urea is not dissolved in the solution.

[0107] Comparative Example 3

[0108] The preparation method of the catalyst is similar to that of Example 1, except that benzoic acid is not dissolved in ethylene glycol.

[0109] Performance Evaluation

[0110] The electrochemical performance and aging resistance of the catalysts of various embodiments and comparative examples were tested, and the results are shown in Table 1.

[0111] Table 1

[0112]

[0113]

[0114] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A nitrogen-doped platinum alloy catalyst, characterized in that: The invention comprises active components and a conductive carrier. The active components comprise a transition metal crystal core and a nitrogen-doped platinum shell layer coated on the surface of the transition metal crystal core.

2. The catalyst according to claim 1, characterized in that The transition metal includes at least one of manganese, iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, osmium, and iridium, preferably at least one of cobalt, nickel, copper, ruthenium, rhodium, and iridium; and / or, the molar ratio of platinum to transition metal is 1:(0.2-5), preferably 1:(0.5-4), more preferably 1:(2-3.5); And / or, the ratio of the sum of the mass of the platinum and the transition metal to the mass of the conductive carrier is 1:(0.05-9), preferably 1:(1-4).

3. The catalyst according to claim 1 or 2, characterized in that The electrochemical mass activity of the catalyst is >0.33A / mgPt, preferably >0.52A / mgPt; And / or, the catalyst is saturated with 0.1 mol·L -1 In the hypochlorous acid solution, the voltage was 200 mV·s in the range of 0.6 to 1.0 V. -1 The half-wave potential drop before and after the accelerated aging test of 5000 cyclic voltammetry scans at a scan rate of is less than 0.09V, preferably ≤0.07V.

4. A method for preparing a nitrogen-doped platinum alloy catalyst, characterized in that: include: S1. adding a transition metal precursor to a solvent containing a controlled coordination agent, and mixing and dissolving the mixture; Then add alkaline solution dropwise; Then, a platinum precursor is added and mixed and dissolved; finally, a nitrogen-containing auxiliary agent is added and mixed and dissolved to obtain a mixed solution; S2. mixing the mixed solution with a conductive carrier, and hydrothermally crystallizing to obtain the catalyst; Optionally, the method further comprises S3. calcining the catalyst under a hydrogen environment and / or subjecting the catalyst to an acid treatment.

5. The preparation method according to claim 4, characterized in that: The transition metal precursor includes at least one of transition metal chloride, bromide, nitrate, sulfate, acetate, and acetylacetonate, preferably at least one of transition metal chloride, nitrate, acetate, and acetylacetonate; preferably, the transition metal includes at least one of manganese, iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, osmium, and iridium, preferably at least one of cobalt, nickel, copper, ruthenium, rhodium, and iridium; And / or, the control coordination agent includes at least one of benzoic acid, 4'-aminomethylfluorescein, polyvinylpyrrolidone, cyclohexylamine, and aniline; and / or, the solvent comprises at least one of water, polyol, benzyl alcohol, and N,N-dimethylformamide, preferably a polyol, more preferably at least one of ethylene glycol, glycerol, diethylene glycol, and triethylene glycol; And / or, the alkaline solution includes at least one of aqueous ammonia, ammonium chloride solution and sodium hydroxide solution; and / or, the platinum precursor comprises at least one of chloroplatinic acid, potassium chloroplatinate, potassium chloroplatinite, platinum acetylacetonate, platinum acetate, tetraammineplatinum dichloride and tetraammineplatinum nitrate, preferably at least one of potassium chloroplatinite, platinum acetylacetonate and platinum acetate; and / or, the nitrogen-containing auxiliary agent comprises at least one of melamine, urea, aniline and ammonium carbonate; And / or, the conductive carrier includes at least one of a conductive carbon carrier, a metal oxide and a metal carbide, preferably at least one of carbon black XC-72 and carbon black BP2000.

6. The preparation method according to claim 4 or 5, characterized in that: The ratio of the sum of the mass of the platinum precursor and the transition metal precursor to the mass of the coordination control agent is 1:(1-9), preferably 1:(3-7), and more preferably 1:(4-6); and / or, the molar ratio of platinum contained in the platinum precursor to the transition metal contained in the transition metal precursor is 1:(0.2-5), preferably 1:(0.5-4), more preferably 1:(2-3.5); and / or, the ratio of the sum of the mass of the platinum contained in the platinum precursor and the transition metal contained in the transition metal precursor to the mass of the conductive carrier is 1:(0.05-9), preferably 1:(1-4); And / or, the mass ratio of the nitrogen-containing auxiliary agent to the conductive carrier is (1-4):

1.

7. The preparation method according to any one of claims 4 to 6, characterized in that: In the step S1, an alkaline solution is added dropwise until the pH of the system is 5 to 10, preferably 7 to 10, and more preferably 7.5 to 9.7; And / or, the hydrothermal crystallization temperature is 150-200° C. and the time is 6-24 hours.

8. The preparation method according to any one of claims 4 to 7, characterized in that: The hydrogen environment is a mixture of hydrogen and argon; preferably, the concentration of the hydrogen is 1-6%; And / or, the calcination temperature is 100-800° C., preferably 300-600° C.; the calcination time is 1-6 hours.

9. The preparation method according to any one of claims 4 to 8, characterized in that: The acid treatment includes impregnating the catalyst with an acid and then performing a heating treatment; Preferably, The acid includes at least one of dilute hydrochloric acid, dilute sulfuric acid, acetic acid and citric acid solution; And / or, the heating treatment is performed at a temperature of 40 to 80° C. and for a time of 0.5 to 3 hours.

10. Use of the nitrogen-doped platinum alloy catalyst according to any one of claims 1 to 3 or the nitrogen-doped platinum alloy catalyst prepared by the preparation method according to any one of claims 4 to 9 in a fuel cell system, especially in a proton membrane exchange fuel cell system.

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