A platinum-based alloy catalyst, its preparation method and application

Abstract

The present invention provides a platinum-based alloy catalyst, a preparation method thereof and an application thereof. The preparation method includes the following steps: (1) preparing a defective carbon material by using a hard template method; (2) mixing a platinum precursor, a transition metal precursor, the defective carbon material and deionized water, and successively performing ultrasonic treatment, freeze-drying and heat treatment to obtain the platinum-based alloy catalyst. The preparation method provided by the present invention fully improves the dispersion degree and uniformity of platinum-based alloy particles on a carrier, further improves the electrochemical performance of the catalyst, reduces the preparation cost, simplifies the preparation process, and is beneficial to large-scale popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and relates to a platinum-based alloy catalyst, in particular to a platinum-based alloy catalyst, a preparation method thereof and an application thereof. Background Art

[0002] The electrochemical reduction of oxygen is a key reaction for improving the performance of energy conversion devices (such as fuel cells, metal-air batteries and electrolyzers). In particular, polymer electrolyte fuel cells (PEFCs) have been recognized as efficient energy converters, capable of achieving low emissions and being environmentally friendly. Noble metal-based (PMG) catalysts are the most widely used catalysts for the cathodic oxygen reduction reaction (ORR) in PEFCs. However, the high cost and low abundance of noble metals have always been the main obstacles to the widespread commercialization of PEFCs. Therefore, it is urgent to develop a catalyst with a low Pt content.

[0003] At present, many technicians use first-row transition metals (Fe, Co, Cu, Ni) to replace part of Pt to form PtM alloy catalysts, which can not only effectively reduce the catalyst cost, but also improve the catalytic performance of the catalyst by modifying the electronic structure of Pt.

[0004] CN 114400334A discloses a platinum-based alloy catalyst, a preparation method thereof and an application thereof. The preparation method of the platinum-based alloy catalyst includes the following steps: (1) mechanically grinding and mixing a certain proportion of Pt / C support, metal precursor and deionized water, and then rapidly freezing and forming at (-200)-(-100)°C to obtain a solid mixture; (2) transferring or in-situ freeze-drying the solid mixture obtained in step (1) to obtain a solid powder; (3) performing rapid heating and sintering treatment on the solid powder in step (2) under a reducing atmosphere, and then rapidly cooling to room temperature to obtain the final catalyst product. However, the preparation method provided by the invention separately loads Pt and the substituted metal, the preparation process is relatively cumbersome, the dispersion degree of platinum-based alloy particles on the C support still needs to be further improved, and there is still great room for improvement in the electrochemical performance of the obtained catalyst.

[0005] Therefore, how to provide a platinum-based alloy catalyst and a preparation method thereof, which can fully improve the dispersion degree and uniformity of platinum-based alloy particles on the support, further improve the electrochemical performance of the catalyst, while reducing the preparation cost and simplifying the preparation process, has become an urgent problem to be solved by those skilled in the art at present. Summary of the Invention

[0006] The object of the present invention is to provide a platinum-based alloy catalyst, a preparation method thereof and an application thereof. The preparation method fully improves the dispersion and uniformity of platinum-based alloy particles on the carrier, further improves the electrochemical performance of the catalyst, reduces the preparation cost, simplifies the preparation process, and is conducive to large-scale popularization and application.

[0007] To achieve the object of this invention, the following technical solutions are adopted in the present invention:

[0008] In a first aspect, the present invention provides a preparation method of a platinum-based alloy catalyst, and the preparation method includes the following steps:

[0009] (1) Prepare a defective-rich carbon material by using a hard template method;

[0010] (2) Mix a platinum precursor, a transition metal precursor, the defective-rich carbon material and deionized water, and sequentially carry out ultrasonic treatment, freeze-drying and heat treatment to obtain a platinum-based alloy catalyst.

[0011] The defective-rich carbon material prepared by the hard template method in the present invention is used as a carrier, which has a stronger metal-carrier interaction than commercial carbon black, avoids the agglomeration of platinum-based alloy particles, and the particle size of the metal particles obtained by freeze-drying is small, which fully improves the dispersion and uniformity of the metal particles on the carrier, further improves the electrochemical performance of the catalyst, reduces the preparation cost, simplifies the preparation process, and is conducive to large-scale popularization and application.

[0012] Preferably, the hard template method in step (1) includes the following steps:

[0013] (1.1) Mix a hard template, an organic monomer, a metal salt and a solvent, stir and evaporate until the solvent is completely removed, and obtain a metal-doped carbon material after carbonization treatment;

[0014] (1.2) Sequentially carry out alkali washing and acid washing on the metal-doped carbon material obtained in step (1.1) to obtain a defective-rich carbon material.

[0015] Preferably, the hard template in step (1.1) includes any one or at least two combinations of SiO2, Al2O3, SBA-15, ZSM-5 or HZSM-5. Typical but non-limiting combinations include the combination of SiO2 and Al2O3, the combination of Al2O3 and SBA-15, the combination of SBA-15 and ZSM-5, the combination of ZSM-5 and HZSM-5, the combination of SiO2, Al2O3 and SBA-15, the combination of Al2O3, SBA-15 and ZSM-5, or the combination of SBA-15, ZSM-5 and HZSM-5. Further preferably, it is SiO2.

[0016] Preferably, the organic monomer in step (1.1) includes any one or a combination of at least two of dicyandiamide, 4-methylimidazole, melamine, phenylenediamine, benzoquinone, dihydroxybenzene, bipyridine, dibromobipyridine, bipyrimidine, bithiophene, dibromobithiophene, phenanthroline, dibromophenanthroline, phenanthrene or bis(2-benzimidazolyl)pyridine. Typical but non-limiting combinations include the combination of dicyandiamide and 4-methylimidazole, the combination of 4-methylimidazole and melamine, the combination of melamine and phenylenediamine, the combination of phenylenediamine and benzoquinone, the combination of benzoquinone and dihydroxybenzene, the combination of dihydroxybenzene and bipyridine, the combination of bipyridine and dibromobipyridine, the combination of dibromobipyridine and bipyrimidine, the combination of bipyrimidine and bithiophene, the combination of bithiophene and dibromobithiophene, the combination of dibromobithiophene and phenanthroline, the combination of phenanthroline and dibromophenanthroline, the combination of dibromophenanthroline and phenanthrene, or the combination of phenanthrene and bis(2-benzimidazolyl)pyridine. Further preferably, it is any one of bithiophene, dibromobithiophene, phenanthroline or dibromophenanthroline.

[0017] Preferably, the metal salt in step (1.1) includes any one or a combination of at least two of Co(NO3)2, Fe(NO3)3, Cr(NO3)3, Cu(NO3)2, Mn(NO3)2, AgNO3, Ni(NO3)2 or Zn(NO3)2. Typical but non-limiting combinations include the combination of Co(NO3)2 and Fe(NO3)3, the combination of Fe(NO3)3 and Cr(NO3)3, the combination of Cr(NO3)3 and Cu(NO3)2, the combination of Cu(NO3)2 and Mn(NO3)2, the combination of Mn(NO3)2 and AgNO3, the combination of AgNO3 and Ni(NO3)2, or the combination of Ni(NO3)2 and Zn(NO3)2. Further preferably, it is Co(NO3)2 or Fe(NO3)3.

[0018] Preferably, the solvent in step (1.1) includes any one or a combination of at least two of deionized water, ethanol, N,N′-dimethylformamide or tetrahydrofuran. Typical but non-limiting combinations include the combination of deionized water and ethanol, the combination of ethanol and N,N′-dimethylformamide, the combination of N,N′-dimethylformamide and tetrahydrofuran, the combination of deionized water, ethanol and N,N′-dimethylformamide, or the combination of ethanol, N,N′-dimethylformamide and tetrahydrofuran.

[0019] In the present invention, deionized water is suitable for dissolving dicyandiamide, 4-methylimidazole and melamine, ethanol is suitable for dissolving phenylenediamine, benzoquinone, dihydroxybenzene, phenanthroline and dibromophenanthroline, N,N′-dimethylformamide is suitable for dissolving bipyridine, dibromobipyridine, bipyrimidine, phenanthrene and bis(2-benzimidazolyl)pyridine, and tetrahydrofuran is suitable for dissolving bithiophene and dibromobithiophene.

[0020] Preferably, the mixing mass ratio of the hard template, organic monomer and metal salt in step (1.1) is 1:1:(1 - 10), for example, it can be 1:1:1, 1:1:2, 1:1:3, 1:1:4, 1:1:5, 1:1:6, 1:1:7, 1:1:8, 1:1:9 or 1:1:10. Further preferably, it is 1:1:2, but it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0021] Preferably, the stirring rate in step (1.1) is 200 - 800 rpm, for example, it can be 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm or 800 rpm. However, it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0022] Preferably, the evaporation temperature in step (1.1) is 50 - 90 °C, for example, it can be 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C or 90 °C. However, it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0023] Preferably, the carbonization temperature in step (1.1) is 700 - 900 °C, for example, it can be 700 °C, 720 °C, 740 °C, 760 °C, 780 °C, 800 °C, 820 °C, 840 °C, 860 °C, 880 °C or 900 °C. However, it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0024] Preferably, the carbonization time in step (1.1) is 1 - 3 h, for example, it can be 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h or 3 h. However, it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0025] Preferably, the carbonization treatment in step (1.1) is carried out in an atmosphere of protective gas, and the protective gas includes nitrogen and / or argon, and the gas flow rate is 0.1 - 0.5 L / min. For example, it can be 0.1 L / min, 0.15 L / min, 0.2 L / min, 0.25 L / min, 0.3 L / min, 0.35 L / min, 0.4 L / min, 0.45 L / min or 0.5 L / min. However, it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0026] Preferably, the alkaline solution used in the alkali washing in step (1.2) includes NaOH solution and / or KOH solution.

[0027] Preferably, the concentration of the alkaline solution used in the alkali washing in step (1.2) is 1.0 - 5.0 mol / L. For example, it can be 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L, 4.0 mol / L, 4.5 mol / L or 5.0 mol / L. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0028] Preferably, the acid solution used in the acid washing in step (1.2) includes any one or a combination of at least two of H2SO4 solution, HCl solution or HNO3 solution. Typical but non - restrictive combinations include the combination of H2SO4 solution and HCl solution, the combination of HCl solution and HNO3 solution, the combination of H2SO4 solution and HNO3 solution, or the combination of H2SO4 solution, HCl solution and HNO3 solution.

[0029] Preferably, the concentration of the acid solution used in the acid washing in step (1.2) is 0.5 - 2.0 mol / L. For example, it can be 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L or 2.0 mol / L. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0030] Preferably, after the alkali washing and acid washing in step (1.2), filtration, washing and drying are carried out in sequence.

[0031] In the present invention, the hard template in the carbon material is removed by the alkali washing, and the unstable metal species doped in the carbon material are removed by the acid washing.

[0032] Preferably, the platinum precursor in step (2) includes chloroplatinic acid and / or tetraammineplatinum nitrate.

[0033] Preferably, the transition metal precursor in step (2) includes any one or a combination of at least two of cobalt precursor, iron precursor, copper precursor or nickel precursor. Typical but non - restrictive combinations include the combination of cobalt precursor and iron precursor, the combination of iron precursor and copper precursor, the combination of copper precursor and nickel precursor, the combination of cobalt precursor, iron precursor and copper precursor, or the combination of iron precursor, copper precursor and nickel precursor. Further preferably, it is cobalt precursor.

[0034] Preferably, the cobalt precursor includes any one or a combination of at least two of cobalt nitrate, cobalt chloride, or cobalt sulfate. Typical but non-limiting combinations include the combination of cobalt nitrate and cobalt chloride, the combination of cobalt chloride and cobalt sulfate, the combination of cobalt nitrate and cobalt sulfate, or the combination of cobalt nitrate, cobalt chloride, and cobalt sulfate.

[0035] Preferably, the mixing mass ratio of the platinum precursor, transition metal precursor, and defect-rich carbon material in step (2) satisfies m(Pt+M):m(C) = 1:(1 - 4). For example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, or 1:4, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0036] Wherein, M is a transition metal element.

[0037] Preferably, the frequency of the ultrasonic treatment in step (2) is 20 - 50 kHz. For example, it can be 20 kHz, 25 kHz, 30 kHz, 35 kHz, 40 kHz, 45 kHz, or 50 kHz, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0038] Preferably, the time of the ultrasonic treatment in step (2) is 10 - 60 min. For example, it can be 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0039] Preferably, the freeze-drying in step (2) includes pre-freezing and drying carried out in sequence.

[0040] Preferably, the temperature of the pre-freezing is -40°C to -10°C. For example, it can be -40°C, -35°C, -30°C, -25°C, -20°C, -15°C, or -10°C, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0041] Preferably, the time of the pre-freezing is 1 - 5 h. For example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0042] Preferably, the vacuum degree of the drying is ≤20 Pa. For example, it can be 2 Pa, 4 Pa, 6 Pa, 8 Pa, 10 Pa, 12 Pa, 14 Pa, 16 Pa, 18 Pa, or 20 Pa, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0043] Preferably, the temperature of the drying is from -30°C to -10°C. For example, it can be -30°C, -28°C, -26°C, -24°C, -22°C, -20°C, -18°C, -16°C, -14°C, -12°C or -10°C, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0044] Preferably, the time of the drying is 10 - 30 h. For example, it can be 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h, 26 h, 28 h or 30 h, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0045] Preferably, the heat treatment in step (2) is carried out in an atmosphere of a reducing gas, and the reducing gas includes hydrogen. The gas flow rate is 0.2 - 1.0 L / min. For example, it can be 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min, 0.9 L / min or 1.0 L / min, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0046] Preferably, the temperature of the heat treatment in step (2) is 600 - 1000°C. For example, it can be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0047] Preferably, the time of the heat treatment in step (2) is 2 - 10 h. For example, it can be 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0048] As a preferred technical solution of the first aspect of the present invention, the preparation method includes the following steps:

[0049] (1) Prepare a defect-rich carbon material by using the hard template method, specifically:

[0050] (1.1) Mix a hard template, an organic monomer, a metal salt, and a solvent, stir at 200 - 800 rpm and evaporate at 50 - 90 °C until the solvent is completely removed, and then perform carbonization treatment at 700 - 900 °C for 1 - 3 h to obtain a metal-doped carbon material; the hard template includes SiO2, the organic monomer includes any one of dithiophene, dibromodithiophene, phenanthroline, or dibromophenanthroline, the metal salt includes Co(NO3)2 or Fe(NO3)3, and the solvent includes ethanol or tetrahydrofuran; the mixing mass ratio of the hard template, the organic monomer, and the metal salt is 1:1:2; the carbonization treatment is carried out in an atmosphere of nitrogen and / or argon, and the gas flow rate is 0.1 - 0.5 L / min;

[0051] (1.2) Sequentially subject the metal-doped carbon material obtained in step (1.1) to alkali washing and acid washing to obtain a defect-rich carbon material; the alkali solution used for alkali washing includes a NaOH solution and / or a KOH solution, and the concentration of the alkali solution is 1.0 - 5.0 mol / L; the acid solution used for acid washing includes any one or a combination of at least two of an H2SO4 solution, an HCl solution, or an HNO3 solution, and the concentration of the acid solution is 0.5 - 2.0 mol / L; after alkali washing and acid washing, filtration, washing, and drying are carried out in sequence;

[0052] (2) Mix a platinum precursor, a cobalt precursor, a defect-rich carbon material, and deionized water, and sequentially perform ultrasonic treatment, freeze-drying, and heat treatment to obtain a platinum-based alloy catalyst; the platinum precursor includes chloroplatinic acid and / or tetraammineplatinum nitrate, and the cobalt precursor includes any one or a combination of at least two of cobalt nitrate, cobalt chloride, or cobalt sulfate; the mixing mass ratio of the platinum precursor, the cobalt precursor, and the defect-rich carbon material satisfies m(Pt + M):m(C) = 1:(1 - 4), and M is a transition metal element; the frequency of the ultrasonic treatment is 20 - 50 kHz, and the time is 10 - 60 min; the freeze-drying includes pre-freezing and drying carried out in sequence, the temperature of the pre-freezing is -40 °C to -10 °C, the time is 1 - 5 h, the vacuum degree of the drying is ≤20 Pa, the temperature is -30 °C to -10 °C, and the time is 10 - 30 h; the temperature of the heat treatment is 600 - 1000 °C, the time is 2 - 10 h, and the heat treatment is carried out in a hydrogen atmosphere, and the gas flow rate is 0.2 - 1.0 L / min.

[0053] In a second aspect, the present invention provides a platinum-based alloy catalyst prepared by the preparation method as described in the first aspect.

[0054] In a third aspect, the present invention provides an application of the platinum-based alloy catalyst as described in the second aspect in a fuel cell cathode catalyst.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The carbon material with rich defects prepared by the present invention using the hard template method is used as a carrier, which has a stronger metal-support interaction than commercial carbon black, avoids the aggregation of platinum-based alloy particles, and the metal particles obtained by freeze-drying have a smaller particle size, which fully improves the dispersion and uniformity of the metal particles on the carrier, further improves the electrochemical performance of the catalyst, reduces the preparation cost, simplifies the preparation process, and is conducive to large-scale popularization and application. Description of the Drawings

[0057] Figure 1 is the SEM photograph of the platinum-based alloy catalyst obtained in Example 1;

[0058] Figure 2 is the SEM photograph of the platinum-based alloy catalyst obtained in Comparative Example 1;

[0059] Figure 3 is the comparison chart of the ORR LSV curves of the platinum-based alloy catalysts obtained in Example 1 and Comparative Example 1. Detailed Embodiments

[0060] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0061] Example 1

[0062] This example provides a platinum-based alloy catalyst and a preparation method thereof. The preparation method includes the following steps:

[0063] (1) Prepare a carbon material with rich defects by the hard template method, specifically:

[0064] (1.1) Mix SiO2, dithiophene, Co(NO3)2 and tetrahydrofuran, stir at 500 rpm and evaporate at 70 °C until the tetrahydrofuran solvent is completely removed, and then perform carbonization treatment at 800 °C for 2 h to obtain Co-doped carbon material; the mixing mass ratio of SiO2, dithiophene and Co(NO3)2 is 1:1:2; the carbonization treatment is carried out in a nitrogen atmosphere, and the gas flow rate is 0.3 L / min;

[0065] (1.2) Sequentially subject the Co-doped carbon material obtained in step (1.1) to alkali washing and acid washing to obtain a carbon material with rich defects; the alkali solution used for alkali washing is NaOH solution, and the concentration of the alkali solution is 3.0 mol / L; the acid solution used for acid washing is HNO3 solution, and the concentration of the acid solution is 1.0 mol / L; after alkali washing and acid washing, filtration, washing and drying are carried out in sequence;

[0066] (2) Mix chloroplatinic acid, cobalt chloride, defective carbon material, and deionized water, and successively perform ultrasonic treatment, freeze-drying, and heat treatment to obtain a platinum-based alloy catalyst; the mixing mass ratio of chloroplatinic acid, cobalt chloride, and defective carbon material is m(Pt + Co) / m(C) = 1:1; the frequency of the ultrasonic treatment is 40 kHz, and the time is 35 min; the freeze-drying includes pre-freezing and drying carried out successively, the pre-freezing temperature is -25 °C, the time is 3 h, the vacuum degree of drying is 10 Pa, the temperature is -20 °C, and the time is 24 h; the heat treatment is carried out in a hydrogen atmosphere, the gas flow rate is 0.5 L / min, after heat treatment at 1000 °C for 2 h, it is cooled to 600 °C at a rate of 1 °C / min and kept warm for 6 h.

[0067] The SEM photograph of the platinum-based alloy catalyst obtained in this example is shown in Figure 1 .

[0068] It can be seen from Figure 1 that the PtCo alloy particles are evenly dispersed on the defective carbon support and have a small particle size, and there is no obvious agglomeration phenomenon.

[0069] Example 2

[0070] This example provides a platinum-based alloy catalyst and a preparation method thereof. The preparation method includes the following steps:

[0071] (1) Prepare a defective carbon material by using the hard template method. Specifically:

[0072] (1.1) Mix SiO2, phenanthroline, Co(NO3)2, and ethanol, stir at 200 rpm and evaporate at 90 °C until the ethanol solvent is completely removed, and perform carbonization treatment at 700 °C for 3 h to obtain Co-doped carbon material; the mixing mass ratio of SiO2, phenanthroline, and Co(NO3)2 is 1:1:5; the carbonization treatment is carried out in an argon atmosphere, and the gas flow rate is 0.1 L / min;

[0073] (1.2) Successively perform alkali washing and acid washing on the Co-doped carbon material obtained in step (1.1) to obtain a defective carbon material; the alkali solution used for alkali washing is a KOH solution, and the concentration of the alkali solution is 1.0 mol / L; the acid solution used for acid washing is an HCl solution, and the concentration of the acid solution is 0.5 mol / L; after alkali washing and acid washing, filtration, washing, and drying are carried out successively;

[0074] (2) Mix tetraammineplatinum nitrate, cobalt nitrate, defective carbon material and deionized water, and successively carry out ultrasonic treatment, freeze-drying and heat treatment to obtain a platinum-based alloy catalyst; the mixing mass ratio of tetraammineplatinum nitrate, cobalt nitrate to defective carbon material is m(Pt+Co) / m(C)=1:1; the frequency of the ultrasonic treatment is 40 kHz and the time is 10 min; the freeze-drying includes pre-freezing and drying carried out successively, and the pre-freezing temperature is -40 °C and the time is 1 h, the vacuum degree of the drying is 20 Pa, the temperature is -20 °C and the time is 10 h; the heat treatment is carried out in a hydrogen atmosphere, the gas flow rate is 1 L / min, first heat-treat at 900 °C for 2 h and then cool down to 600 °C at a rate of 1 °C / min and keep warm for 6 h.

[0075] The microscopic morphology of the platinum-based alloy catalyst obtained in this example is similar to that of Example 1, so it will not be elaborated here.

[0076] Example 3

[0077] This example provides a platinum-based alloy catalyst and a preparation method thereof. The preparation method includes the following steps:

[0078] (1) Prepare defective carbon material by using the hard template method, specifically:

[0079] : (1.1) Mix SiO2, dicyandiamide, Co(NO3)2 and deionized water, stir at 800 rpm and evaporate at 50 °C until the deionized water solvent is completely removed, and carry out carbonization treatment at 900 °C for 1 h to obtain Co-doped carbon material; the mixing mass ratio of SiO2, dicyandiamide to Co(NO3)2 is 1:1:10; the carbonization treatment is carried out in a nitrogen atmosphere, and the gas flow rate is 0.5 L / min;

[0080] (1.2) Successively carry out alkali washing and acid washing on the Co-doped carbon material obtained in step (1.1) to obtain defective carbon material; the alkali solution used for alkali washing is NaOH solution, and the concentration of the alkali solution is 5.0 mol / L; the acid solution used for acid washing is HNO3 solution, and the concentration of the acid solution is 2.0 mol / L; filtration, washing and drying are carried out successively after alkali washing and acid washing;

[0081] (2) Mix chloroplatinic acid, cobalt sulfate, defect-rich carbon material and deionized water, and successively carry out ultrasonic treatment, freeze-drying and heat treatment to obtain a platinum-based alloy catalyst; the mixing mass ratio of chloroplatinic acid, cobalt sulfate to the defect-rich carbon material is m(Pt + Co) / m(C) = 1:1; the frequency of the ultrasonic treatment is 40 kHz and the time is 60 min; the freeze-drying includes pre-freezing and drying carried out successively, and the pre-freezing temperature is -10 °C and the time is 5 h, the vacuum degree of drying is 15 Pa, the temperature is -20 °C and the time is 30 h; the heat treatment is carried out in a hydrogen atmosphere, the gas flow rate is 0.2 L / min, first heat-treat at 1000 °C for 2 h and then cool down to 600 °C at a rate of 1 °C / min and keep warm for 6 h.

[0082] The microscopic morphology of the platinum-based alloy catalyst obtained in this example is similar to that of Example 1, so it will not be elaborated here.

[0083] Example 4

[0084] This example provides a platinum-based alloy catalyst and a preparation method thereof. The preparation method is the same as that of Example 1 except that SiO2 in step (1) is changed to Al2O3, and the other steps and conditions are the same, so it will not be elaborated here.

[0085] The microscopic morphology of the platinum-based alloy catalyst obtained in this example is similar to that of Example 1, so it will not be elaborated here.

[0086] Example 5

[0087] This example provides a platinum-based alloy catalyst and a preparation method thereof. The preparation method is the same as that of Example 1 except that Co(NO3)2 in step (1) is changed to Fe(NO3)3, and the other steps and conditions are the same, so it will not be elaborated here.

[0088] The microscopic morphology of the platinum-based alloy catalyst obtained in this example is similar to that of Example 1, so it will not be elaborated here.

[0089] Comparative Example 1

[0090] This comparative example provides a platinum-based alloy catalyst and a preparation method thereof. The specific preparation method is as follows: Mix chloroplatinic acid, cobalt chloride, commercial carbon black (CABOT BP2000) and deionized water, and successively perform ultrasonic treatment, freeze-drying and heat treatment to obtain a platinum-based alloy catalyst. The mixing mass ratio of chloroplatinic acid, cobalt chloride to commercial carbon black is m(Pt+Co) / m(C)=1:1. The frequency of the ultrasonic treatment is 40 kHz and the time is 35 min. The freeze-drying includes pre-freezing and drying carried out successively. The pre-freezing temperature is -25°C and the time is 3 h. The vacuum degree of drying is 10 Pa, the temperature is -20°C, and the time is 24 h. The heat treatment is carried out in a hydrogen atmosphere with a gas flow rate of 0.5 L / min. First, heat-treat at 1000°C for 2 h and then cool down to 600°C at a rate of 1°C / min and keep warm for 6 h.

[0091] The SEM photograph of the platinum-based alloy catalyst obtained in this comparative example is shown in Figure 2 .

[0092] It can be seen from Figure 2 that the particle size distribution of PtCo alloy particles on commercial carbon black is uneven, there is obvious particle agglomeration, and the particle size of some particles > 20 nm.

[0093] The platinum-based alloy catalysts obtained in Example 1 and Comparative Example 1 were respectively used as oxygen reduction catalysts for electrochemical testing. Linear sweep testing (0.05 - 1.10 V vs RHE, 20 mV / s) was carried out in a 0.1 M HClO4 solution. The results are as Figure 3 shown.

[0094] It can be seen from Figure 3 that the initial potential, half-wave potential of Example 1 are higher than those of Comparative Example 1 and the limiting current density is larger. That is, compared with Comparative Example 1, the platinum-based alloy catalyst obtained in Example 1 has better electrocatalytic activity for the oxygen reduction reaction.

[0095] Thus, it can be seen that the defective carbon material rich in defects prepared by the hard template method of the present invention is used as a carrier, which has a stronger metal-support interaction than commercial carbon black, avoids the agglomeration of platinum-based alloy particles, and the particle size of the metal particles obtained by freeze-drying is smaller, which fully improves the dispersion degree and uniformity of the metal particles on the carrier, further improves the electrochemical performance of the catalyst, reduces the preparation cost, simplifies the preparation process, and is conducive to large-scale popularization and application.

[0096] The applicant declares that the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for preparing a platinum-based alloy catalyst, characterized in that, The preparation method includes the following steps: (1) Prepare defect-rich carbon materials by using the hard template method; The hard template method includes the following steps: (1.1) Mix the hard template, organic monomer, metal salt and solvent, stir and evaporate until the solvent is completely removed, and obtain metal-doped carbon materials after carbonization treatment; (1.2) Subject the metal-doped carbon materials obtained in step (1.1) to alkali washing and acid washing in sequence to obtain defect-rich carbon materials; The mixing mass ratio of the hard template, organic monomer and metal salt is 1:1:(1-10); the organic monomer includes any one or a combination of at least two of dicyandiamide, 4-methylimidazole, melamine, phenylenediamine, benzoquinone, dihydroxybenzene, bipyridine, dibromobipyridine, bipyrimidine, dithiophene, dibromodithiophene, phenanthroline, dibromophenanthroline, phenanthrene or bis(2-benzimidazolyl)pyridine; (2) Mix the platinum precursor, transition metal precursor, defect-rich carbon materials and deionized water, and perform ultrasonic treatment, freeze-drying and heat treatment in sequence to obtain a platinum-based alloy catalyst; The mixing mass ratio of the platinum precursor, transition metal precursor and defect-rich carbon materials satisfies m(Pt+M):m(C)=1:(1-4), and M is a transition metal element; The freeze-drying includes pre-freezing and drying carried out in sequence; the temperature of the pre-freezing is -35°C to -10°C; the temperature of the drying is -30°C to -10°C.

2. The preparation method according to claim 1, characterized in that, The hard template in step (1.1) includes any one or a combination of at least two of SiO2, Al2O3, SBA-15, ZSM-5 or HZSM-5.

3. The preparation method according to claim 2, characterized in that, The hard template in step (1.1) is SiO2.

4. The preparation method according to claim 1, wherein The organic monomer in step (1.1) is any one of dithiophene, dibromodithiophene, phenanthroline or dibromophenanthroline.

5. The preparation method according to claim 1, characterized in that, The metal salt in step (1.1) includes any one or a combination of at least two of Co(NO3)2, Fe(NO3)3, Cr(NO3)3, Cu(NO3)2, Mn(NO3)2, AgNO3, Ni(NO3)2 or Zn(NO3)2.

6. The preparation method according to claim 5, wherein The metal salt in step (1.1) is Co(NO3)2 or Fe(NO3)3.

7. The preparation method according to claim 1, characterized in that, The solvent in step (1.1) includes any one or a combination of at least two of deionized water, ethanol, N,N′-dimethylformamide or tetrahydrofuran.

8. The preparation method according to claim 1, characterized in that, The mixing mass ratio of the hard template, organic monomer and metal salt in step (1.1) is 1:1:

2.

9. The preparation method according to claim 1, characterized in that, The stirring rate in step (1.1) is 200-800 rpm.

10. The preparation method according to claim 1, wherein The evaporation temperature in step (1.1) is 50-90°C.

11. The preparation method according to claim 1, wherein, The temperature of the carbonization treatment in step (1.1) is 700-900°C.

12. The preparation method according to claim 1, wherein, The time of the carbonization treatment in step (1.1) is 1-3 h.

13. The preparation method according to claim 1, characterized in that, The carbonization treatment in step (1.1) is carried out in an atmosphere of a protective gas, and the protective gas includes nitrogen and / or argon, and the gas flow rate is 0.1-0.5 L / min.

14. The preparation method according to claim 1, wherein, The alkali solution used for the alkali washing in step (1.2) includes NaOH solution and / or KOH solution.

15. The preparation method according to claim 1, wherein The concentration of the alkaline solution used in the alkali washing described in step (1.2) is 1.0 - 5.0 mol / L.

16. The preparation method according to claim 1, wherein, The acid solution used in the acid washing described in step (1.2) includes any one or a combination of at least two of H2SO4 solution, HCl solution, or HNO3 solution.

17. The preparation method according to claim 1, wherein The concentration of the acid solution used in the acid washing described in step (1.2) is 0.5 - 2.0 mol / L.

18. The preparation method according to claim 1, characterized in that, After the alkali washing and acid washing in step (1.2), filtration, washing, and drying are carried out in sequence.

19. The preparation method according to claim 1, characterized in that, The platinum precursor described in step (2) includes chloroplatinic acid and / or tetraammineplatinum nitrate.

20. The preparation method according to claim 1, wherein, The transition metal precursor described in step (2) includes any one or a combination of at least two of cobalt precursor, iron precursor, copper precursor, or nickel precursor.

21. The preparation method according to claim 20, characterized in that, The transition metal precursor described in step (2) is a cobalt precursor.

22. The preparation method according to claim 21, wherein, The cobalt precursor includes any one or a combination of at least two of cobalt nitrate, cobalt chloride, or cobalt sulfate.

23. The preparation method according to claim 1, wherein The frequency of the ultrasonic treatment described in step (2) is 20 - 50 kHz.

24. The preparation method according to claim 1, characterized in that, The time of the ultrasonic treatment described in step (2) is 10 - 60 min.

25. The preparation method according to claim 1, characterized in that, The time of the pre-freezing is 1 - 5 h.

26. The preparation method according to claim 1, wherein The vacuum degree of the drying is ≤20 Pa.

27. The preparation method according to claim 1, wherein, The time of the drying is 10 - 30 h.

28. The preparation method according to claim 1, wherein, The heat treatment described in step (2) is carried out in an atmosphere of reducing gas, and the reducing gas includes hydrogen, and the gas flow rate is 0.2 - 1.0 L / min.

29. The preparation method according to claim 1, characterized in that, The temperature of the heat treatment described in step (2) is 600 - 1000 °C.

30. The preparation method according to claim 1, characterized in that, The time of the heat treatment described in step (2) is 2 - 10 h.

31. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Prepare the defect-rich carbon material by the hard template method, specifically: (1.1) Mix the hard template, organic monomer, metal salt, and solvent, stir at 200 - 800 rpm and evaporate at 50 - 90 °C until the solvent is completely removed, and carry out carbonization treatment at 700 - 900 °C for 1 - 3 h to obtain the metal-doped carbon material; the hard template includes SiO2, the organic monomer includes any one of dithiophene, dibromodithiophene, phenanthroline, or dibromophenanthroline, the metal salt includes Co(NO3)2 or Fe(NO3)3, and the solvent includes ethanol or tetrahydrofuran; the mixing mass ratio of the hard template, organic monomer, and metal salt is 1:1:2; the carbonization treatment is carried out in an atmosphere of nitrogen and / or argon, and the gas flow rate is 0.1 - 0.5 L / min; (1.2) Sequentially subject the metal-doped carbon material obtained in step (1.1) to alkali washing and acid washing to obtain the defect-rich carbon material; the alkaline solution used in the alkali washing includes NaOH solution and / or KOH solution, and the concentration of the alkaline solution is 1.0 - 5.0 mol / L; the acid solution used in the acid washing includes any one or a combination of at least two of H2SO4 solution, HCl solution, or HNO3 solution, and the concentration of the acid solution is 0.5 - 2.0 mol / L; after the alkali washing and acid washing, filtration, washing, and drying are carried out in sequence. (2) Mix the platinum precursor, cobalt precursor, defect-rich carbon material and deionized water, and successively carry out ultrasonic treatment, freeze-drying and heat treatment to obtain a platinum-based alloy catalyst; the platinum precursor includes chloroplatinic acid and / or tetraammineplatinum nitrate, and the cobalt precursor includes any one or a combination of at least two of cobalt nitrate, cobalt chloride or cobalt sulfate; the mixing mass ratio of the platinum precursor, cobalt precursor and defect-rich carbon material satisfies m(Pt+M):m(C)=1:(1-4), and M is a transition metal element; the frequency of the ultrasonic treatment is 20-50 kHz and the time is 10-60 min; the freeze-drying includes pre-freezing and drying carried out successively, and the pre-freezing temperature is -35°C to -10°C, the time is 1-5 h, the vacuum degree of the drying is ≤20 Pa, the temperature is -30°C to -10°C, and the time is 10-30 h; the heat treatment temperature is 600-1000°C, the time is 2-10 h, and the heat treatment is carried out in a hydrogen atmosphere with a gas flow rate of 0.2-1.0 L / min.

32. A platinum-based alloy catalyst prepared by the preparation method according to any one of claims 1-31.

33. An application of the platinum-based alloy catalyst according to claim 32 in a fuel cell cathode catalyst.

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