Preparation process of carbon-based platinum-iron alloy catalyst and catalyst

Abstract

The invention discloses a preparation process and catalyst of a carbon-based platinum-iron alloy catalyst, relating to the technical field of fuel cell catalyst material preparation. The invention aims to solve the problems of existing methods having significant safety hazards or high costs, which are not conducive to large-scale production, while ensuring the catalytic activity of the catalyst. The invention comprises the following steps: mixing an iron salt solution A and an organic ligand solution B prepared from a bidentate ligand capable of binding iron ions and platinum ions, stirring the mixture to uniformly react, adding a platinum salt solution C, heating the mixture to a constant temperature to react sufficiently, adding an organic ligand solution D capable of binding iron ions but not platinum ions, filtering the mixture after the temperature reaction is completed, washing the solid portion with an ethanol aqueous solution, drying the mixture to obtain a powder, and subjecting the mixture to high-temperature alloying treatment to obtain the platinum-iron alloy catalyst. The process steps of the invention are simple, easy to operate and control, highly safe, low in cost, suitable for large-scale production, and the obtained catalyst has excellent properties such as electrocatalytic activity.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell catalyst material preparation, and in particular to a preparation process and catalyst of a carbon-based platinum-iron alloy catalyst. Background Art

[0002] With the rapid development of industry, the crisis of fossil energy shortage is affecting human production and life. In pursuit of sustainable development, the development and promotion of new clean and renewable energy sources has become an inevitable trend in social development. Hydrogen fuel cells, as power generation devices that can directly convert the chemical energy of hydrogen into electrical energy and efficiently perform external work, have attracted widespread attention due to their high energy density, high energy conversion efficiency, and environmental friendliness. During hydrogen fuel cell operation, the cathode oxygen reduction reaction (ORR) is a key step limiting energy conversion efficiency due to its complex process and slow kinetics. Currently, precious metal platinum-based catalysts are considered the best oxygen reduction electrocatalysts, but their scarcity, high recycling costs, and poor durability hinder their large-scale commercial application. Cutting-edge research has shown that alloying Pt with the variable-valence transition metal iron (Fe) can modify the geometric, electronic, and stress effects of nanometal catalysts, thereby reducing Pt dosage while improving electrocatalyst activity and stability. To accelerate commercialization of fuel cell applications such as combined heat and power generation (CHP) and fuel cell vehicles, component costs must be significantly reduced. Accelerating the development of key platinum alloy catalyst technologies can effectively reduce the amount of platinum required in fuel cell membrane electrodes while ensuring uncompromising cell performance and lifespan. The development of platinum-iron alloy catalysts holds significant commercial value and market potential for the development of advanced fuel cells.

[0003] At present, there are mainly the following synthetic technology routes for platinum-iron alloy catalysts:

[0004] (1) Liquid phase reduction method, using chloroplatinic acid and ferrous nitrate as precursors, first pickling the carbon nanotubes, mixing the carbon support and the precursor salt with an ethylene glycol solution, and preparing carbon nanotube-loaded platinum-iron alloy nanoparticles in the ethylene glycol solution by sodium borohydride reduction method, and then converting them into carbon nanotube-loaded platinum-iron superlattice alloy nanoparticles by thermal annealing treatment under an inert gas atmosphere (for example, the invention patent with the publication number CN105489907B, entitled A Carbon Nanotube-Loaded Platinum-Iron Superlattice Alloy Nanoparticle and Its Preparation Method, discloses this method); this method uses alcohols as organic solvents for reaction, and adds sodium borohydride as a reducing agent for reduction. The process is simple, safe to operate, does not require the introduction of reducing gas during the thermal annealing process, has strong controllability, and can improve the catalyst reaction activity and stability. However, concentrated sulfuric acid and concentrated nitric acid are required in the reaction, and sodium borohydride is a strong reducing agent. The reduction reaction is relatively violent, and the requirements for the reaction device and operation process are high, which is not conducive to large-scale production and preparation.

[0005] (2) Electric pulse reduction method, the preparation method of which is to mix the platinum source and the iron source by liquid phase method, add them to the surface of the carbonaceous reducing agent, volatilize and remove the solvent, apply ultrashort current pulse to the precursor mixture under protective atmosphere for reduction reaction, and quickly quench to room temperature after the reduction reaction is completed to obtain platinum-iron alloy nanoparticles, and then mix the platinum-iron alloy nanoparticles with activated alumina sol, demulsify and precipitate, and then centrifuge and further vacuum dry to obtain platinum-iron alloy catalyst (for example, the invention patent with announcement number CN111921541B, entitled A platinum-iron alloy catalyst and its preparation method and application in VOCs catalytic oxidation, discloses this method); this method first mixes the platinum precursor and the carbon carrier in liquid phase, concentrates and dries, and then performs electric pulse reduction, which does not introduce too many impurities and the preparation process is relatively simple. However, inert gas protection is required during the electric pulse reduction process, which places high requirements on the reaction equipment, and the use of electric pulses has certain safety hazards.

[0006] (3) Hydrogen reduction method: a certain amount of platinum source and iron source are added to a surfactant, and then the temperature is raised to the reduction temperature at a certain heating rate, and then the gas flow is switched to a hydrogen-nitrogen mixture, and the platinum-iron nano alloy is obtained after a period of reduction. The nano alloy is washed with ethanol and hexane, and dispersed in a mixture of hexane and acetone. Tungsten oxide modified with surface organic matter is added, ultrasonically dispersed, dried, and then introduced into an inert atmosphere. After heat treatment at a certain temperature for a period of time, the tungsten oxide-supported platinum-iron nano alloy catalyst is obtained (for example, the invention patent application with publication number CN114289032A, entitled "A Preparation Method and Application of Tungsten Oxide-supported Platinum-iron Nano Alloy Catalyst" discloses this method); this method first mixes the platinum source and the iron source, and then introduces hydrogen to reduce the platinum-iron nano alloy, which is then further loaded onto a tungsten oxide carrier. The prepared catalyst has the advantages of good dispersibility and high catalytic activity, but hydrogen is a flammable gas, and organic reagents such as oleylamine, oleic acid, and acetone need to be introduced during the synthesis process, making safety and environmental protection issues difficult to solve.

[0007] (4) In situ reduction method, a porous template and a tetraphenylporphyrin / tetraphenyl iron porphyrin mixture are mixed to obtain a porous template with a surface coated with tetraphenylporphyrin / tetraphenyl iron porphyrin, which is further leached with alkali to obtain a porous tetraphenylporphyrin / tetraphenyl iron porphyrin material, and then the porous tetraphenylporphyrin / tetraphenyl iron porphyrin material is mixed with pyrrole in water for adsorption, and then a chloroplatinic acid aqueous solution is added to react to obtain a composite material, and finally the composite material is pyrolyzed to obtain a carbon-based platinum-iron alloy material (for example, The invention patent application for a carbon-based platinum-iron alloy material and its application, CN113571714A, discloses this method. The method adopts an in-situ synthesis method, in which a template is first mixed with an iron source precursor to form a composite material, and then heat-treated after impregnation with a platinum salt to obtain a carbon-based platinum-iron alloy material. The coordination effect of porphyrin and the protective effect of polypyrrole can avoid excessive sintering and agglomeration of metal active sites, which is conducive to improving the uniformity of platinum-iron sites and effectively increasing catalyst stability. However, in this synthesis process, tetraphenylporphyrin and tetraphenylporphyrin cobalt are used as raw materials. These two raw materials are expensive, and a silicon oxide template is introduced in the reaction. The preparation process is relatively complicated and costly, which is unfavorable for large-scale production. Summary of the Invention

[0008] The purpose of the present invention is to provide a preparation process and catalyst of a carbon-based platinum-iron alloy catalyst, so as to solve the problems that the existing methods have major safety hazards or high costs and are not conducive to large-scale production while ensuring the catalytic activity of the catalyst.

[0009] To achieve the above object, the present invention provides the following technical solution: a process for preparing a carbon-based platinum-iron alloy catalyst, comprising the following steps:

[0010] S1. Prepare iron salt solution A;

[0011] S2. Prepare an organic ligand solution B capable of binding iron ions and platinum ions, wherein the organic ligand is a bidentate ligand;

[0012] S3. Prepare platinum salt solution C;

[0013] S4. Prepare an organic ligand solution D that can bind iron ions but not platinum ions;

[0014] S5. The iron salt solution A and the organic ligand solution B were mixed at room temperature and stirred to make the reaction uniform;

[0015] S6. Platinum salt solution C was added to the mixed solution obtained in S5, and the mixed solution was heated and the reaction was fully carried out at a constant temperature, and the reaction temperature was controlled within the range of 40 to 60 ℃;

[0016] S7. The organic ligand solution D is added to the mixed solution obtained in S6, and the mixed solution is heated to control the heating temperature of the mixed solution to 90 to 120 ° C, and the reaction time is controlled according to the desired particle size;

[0017] S8. After the reaction is completed, the liquid in the mixture obtained in S7 is removed, the solid portion is washed with an aqueous ethanol solution, and then dried to obtain a powder;

[0018] S9. Perform high-temperature alloying treatment on the powder to obtain a platinum-iron alloy catalyst.

[0019] Preferably, the solute of the iron salt solution is one or more of ferric nitrate, ferric chloride, and ferric acetate, the solvent is pure water, and the concentration of iron ions in the solution is 0.05 to 0.5 mol / L; the solute of the platinum salt solution is one or more of chloroplatinic acid, potassium chloroplatinate, and sodium chloroplatinate, the solvent is pure water, and the concentration of platinum ions in the solution is 0.05 to 0.5 mol / L.

[0020] Preferably, in step S2, the bidentate ligand in the organic ligand solution B is one or more of 2-methylimidazole, o-phenanthroline, and ethylenediamine, the solvent is one or more of methanol, ethanol, and propanol, and the concentration of the organic ligand in the solution is 0.1-1 mol / L.

[0021] Preferably, in step S4, the organic ligand in the organic ligand solution D is benzoic acid and / or benzoic anhydride, the solvent is one or more of ethylene glycol, propylene glycol, and glycerol, and the concentration of the organic ligand in the solution is 0.1-1 mol / L.

[0022] Preferably, in step S5, the reaction time is controlled within 1 to 3 hours; in step S6, the heating reaction time of the mixed solution is controlled within 4 to 6 hours; and in step S7, the reaction time is controlled within 8 to 12 hours.

[0023] Preferably, in step S8, the liquid in the mixture is removed by filtration; the volume fraction of ethanol in the ethanol aqueous solution is 50-70%, and the drying temperature is controlled at 60-80°C.

[0024] Preferably, in step S9, the powder obtained in step S8 is spread on the bottom of the crucible, transferred to a tube furnace, and protected by nitrogen or inert gas, and subjected to high-temperature heat treatment at 300-800° C. for 1-3 hours.

[0025] Another technical solution provided by the present invention is a carbon-based platinum-iron alloy catalyst prepared by the above-mentioned preparation process.

[0026] Preferably, the particle size of the catalyst is 200-300 nm, the site size of the platinum-iron alloy is 4-8 nm, and the specific surface area is 500-600 m 2 / g, pore volume 0.15~0.25m 3 / g, half-wave potential 0.9~0.95V.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The preparation process of this carbon-based platinum-iron alloy catalyst utilizes a continuous self-assembly method combined with an in-situ reduction method to prepare the catalyst. Organic ligands such as 2-methylimidazole and o-phenanthroline are mixed with a platinum source and an iron source. The bidentate ligand's ability to simultaneously bind two metal ions allows the organic ligand to simultaneously bind to both iron and platinum ions. Organic ligands such as benzoic acid / benzoic anhydride are then introduced to bind to the iron ions to form a metal-organic framework (Fe-MOF). Combined with the in-situ reduction method, the decomposition of the organic ligand during high-temperature heat treatment without the introduction of an additional reducing agent effectively reduces the platinum and iron ions with the generated CO gas, ultimately yielding highly active carbon-based platinum-iron alloy nanoparticles.

[0029] 2. Compared with the traditional process of introducing two metal ions onto the carrier and then reducing them, the preparation process of this carbon-based platinum-iron alloy catalyst can more effectively ensure close contact between the platinum and iron metal sites, thereby promoting the formation of the platinum-iron alloy phase. The formation of a large number of platinum-iron alloy sites is a key factor in high catalytic activity.

[0030] 3. The preparation process of this carbon-based platinum-iron alloy catalyst adopts in-situ reduction and high-temperature heat treatment of the precursor under the protection of an inert atmosphere. This oxygen-deficient atmosphere will cause a small amount of CO gas to be produced during the decomposition of the precursor. The CO gas can effectively reduce platinum and iron from an ionic state to a metallic state. During the reduction process, the positions of the platinum and iron ions will not migrate. At the same time, the gas produced by the decomposition is also beneficial to inhibit the agglomeration of nanoparticles, so that they always maintain a highly dispersed state and promote the improvement of catalytic activity.

[0031] 4. The preparation process of this carbon-based platinum-iron alloy catalyst does not require relatively dangerous raw materials such as concentrated acid, strong reducing agents, and hydrogen. The reaction is mild, safe, and has relatively low equipment requirements. In addition, the raw material cost is relatively low, the process steps are simple, easy to operate and control, and is suitable for large-scale production applications.

[0032] 5. The carbon-based platinum-iron alloy catalyst has uniform particle size, and there is no obvious agglomeration or sintering between the particles, indicating good dispersion. The platinum-iron alloy sites are evenly distributed on the surface of the sample particles, and there is no particle agglomeration and growth caused by high-temperature sintering. The high specific surface area and large pore volume are conducive to the mass and heat transfer process of the catalytic reaction, which can further promote the catalytic reaction. The high half-wave potential means higher electrocatalytic efficiency, obvious characteristic peaks of the oxygen reduction reaction, and good electrocatalytic activity for the oxygen reduction reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a scanning electron microscope (SEM) image of the sample prepared in Example 1 of the present invention.

[0034] Figure 2 This is a transmission electron microscope (TEM) image of the sample prepared in Example 1 of the present invention.

[0035] Figure 3 These are the electrochemical test results of linear sweep voltammetry (LSV) of the samples prepared in the examples of the present invention and the comparative examples.

[0036] Figure 4 These are the electrochemical test results of cyclic voltammetry (CV) of the samples prepared in the examples of the present invention and the comparative examples. DETAILED DESCRIPTION

[0037] A process for preparing a carbon-based platinum-iron alloy catalyst comprises the following steps:

[0038] S1. Prepare an iron salt solution A; the solute of the iron salt solution may be one or more of ferric nitrate, ferric chloride, ferric acetate, etc., the solvent is pure water, and the concentration of iron ions in the solution is preferably selected to be 0.05 to 0.5 mol / L;

[0039] S2. Prepare an organic ligand solution B capable of binding iron ions and platinum ions, wherein the organic ligand is a bidentate ligand; the bidentate ligand may be one or more of 2-methylimidazole, o-phenanthroline, ethylenediamine, etc., and the solvent may be one or more of methanol, ethanol, and propanol (which can dissolve the above ligands). The concentration of the organic ligand in the solution is preferably selected to be 0.1 to 1 mol / L;

[0040] S3. Preparation of a platinum salt solution C; the solute of the platinum salt solution may be one or more of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, etc., the solvent is pure water, and the concentration of platinum ions in the solution is preferably selected to be 0.05 to 0.5 mol / L;

[0041] S4. Prepare an organic ligand solution D that binds to iron ions and does not bind to platinum ions; the organic ligand may be benzoic acid and / or benzoic anhydride, and the solvent may be one or more of ethylene glycol, propylene glycol, glycerol, etc. (which can dissolve the above ligands). The concentration of the organic ligand in the solution is preferably selected to be 0.1 to 1 mol / L;

[0042] S5. Mix the iron salt solution A and the organic ligand solution B at room temperature and keep stirring to make the reaction uniform. For reference, the time control can be 1 to 3 hours;

[0043] S6. Platinum salt solution C is added to the mixed solution obtained in S5, and the mixed solution is heated and reacted at a constant temperature. The constant temperature reaction temperature is controlled in the range of 40 to 60 ° C. For reference, the reaction time can be controlled in the range of 4 to 6 hours, and as much as possible, not less than 4 hours to ensure that the most suitable catalyst structure to be prepared is obtained;

[0044] S7. Add the organic ligand solution D to the mixed solution obtained in S6, and heat the mixed solution to control the heating temperature of the mixed solution to 90-120° C. The reaction time is controlled according to the desired particle size. For reference, the reaction time can be controlled within 8-12 h. If the reaction time is less than 8 h, the yield and structure will be affected. If the reaction time is more than 12 hours, the particle size will be too large, which will affect the electrocatalytic activity and other properties of the final product (of course, the product can also be obtained outside this time range. Here, only the preferred solution is provided for reference);

[0045] S8. After the reaction is completed, the liquid in the mixture obtained in S7 is removed, and optionally, the mixture is separated by suction filtration, and the solid portion is washed with an ethanol aqueous solution and dried to obtain a powder, wherein the volume fraction of ethanol in the ethanol aqueous solution is preferably 50 to 70%, and the drying temperature is preferably controlled at 60 to 80 ° C;

[0046] S9. The powder is subjected to high-temperature alloying treatment to obtain a platinum-iron alloy catalyst. Specifically, the following method can be adopted: the powder obtained in step S8 is spread flat on the bottom of a crucible, transferred to a tubular furnace, and nitrogen or inert gas is introduced for protection, and high-temperature heat treatment is performed at 300-800°C for 1-3h.

[0047] The catalyst prepared by the above process can have the following characteristics: particle size of 200-300nm, platinum-iron alloy site size of 4-8nm, specific surface area of ​​500-600m 2 / g, pore volume 0.15~0.25m 3 / g, half-wave potential of 0.9-0.95V, with obvious characteristic peak of oxygen reduction reaction, high electrocatalytic efficiency and good electrocatalytic activity.

[0048] Example 1:

[0049] Weigh 2.4g of ferric nitrate and dissolve it in 100mL of pure water, denoted as Solution A. Weigh 3.3g of 2-methylimidazole and dissolve it in 200mL of methanol, denoted as Solution B. Weigh 5.2g of chloroplatinic acid and dissolve it in 100mL of pure water, denoted as Solution C. Weigh 7.3g of benzoic acid and dissolve it in 300mL of ethylene glycol, denoted as Solution D. Mix Solutions A and B at room temperature and stir to react for 1 hour. Add Solution C to the mixed solution, heat the mixed solution, and react at 40°C for 4 hours. Finally, add Solution D to the mixed solution, raise the reaction temperature of the mixed solution to 100°C, and maintain the reaction temperature for 8 hours. After the reaction is completed, the mixed solution is filtered and separated, washed with a mixture of ethanol and water, where the volume fraction of ethanol is 50%, and then air-dried at 60°C to obtain a powder. The obtained mixed powder was spread flat on the bottom of a crucible, transferred to a tube furnace, introduced with Ar for inert gas protection, and subjected to high-temperature heat treatment at 600°C to obtain a platinum-iron alloy catalyst, which was recorded as PtFeC-1.

[0050] Example 2:

[0051] Weigh 4.1g of ferric chloride and dissolve it in 100mL of pure water, denoted as Solution A. Weigh 14.4g of o-phenanthroline and dissolve it in 200mL of ethanol, denoted as Solution B. Weigh 9.7g of potassium chloroplatinate and dissolve it in 100mL of pure water, denoted as Solution C. Weigh 27.1g of benzoic anhydride and dissolve it in 300mL of propylene glycol, denoted as Solution D. Mix Solutions A and B at room temperature and allow to react with stirring for 2 hours. Add Solution C to the mixed solution, heat the mixed solution, and react at 50°C for 5 hours. Finally, add Solution D to the mixed solution, raise the reaction temperature to 110°C, and maintain the reaction temperature for 10 hours. After the reaction, filter the mixed solution, wash it with a mixture of ethanol and water, where the volume fraction of ethanol is 60%, and then air-dry it at 70°C to obtain a powder. The obtained mixed powder was spread flat on the bottom of the crucible, transferred to a tube furnace, and protected by N2. It was subjected to high-temperature heat treatment at 700°C to obtain a platinum-iron alloy catalyst, which was recorded as PtFeC-2.

[0052] Example 3:

[0053] Weigh 7.8g of ferric acetate and dissolve it in 100mL of pure water, denoted as Solution A. Weigh 9.6g of ethylenediamine and dissolve it in 200mL of propanol, denoted as Solution B. Weigh 22.5g of sodium chloroplatinate and dissolve it in 100mL of pure water, denoted as Solution C. Weigh 32.9g of benzoic acid and dissolve it in 300mL of glycerol, denoted as Solution D. Mix Solutions A and B at room temperature and stir to react for 3 hours. Add Solution C to the mixed solution, heat the mixed solution, and react at 60°C for 6 hours. Finally, add Solution D to the mixed solution, raise the reaction temperature of the mixed solution to 120°C, and maintain the reaction temperature for 12 hours. After the reaction is completed, the mixed solution is filtered and separated, washed with a mixture of ethanol and water, with the volume fraction of ethanol being 70%, and then air-dried at 80°C to obtain a powder. The obtained mixed powder was spread on the bottom of a crucible, transferred to a tube furnace, introduced with He for inert gas protection, and subjected to high-temperature heat treatment at 800°C to obtain a platinum-iron alloy catalyst, which was recorded as PtFeC-3.

[0054] Comparative Example 1:

[0055] 0.05g of carbon nanotubes impregnated with nitric acid were weighed and placed in a three-necked flask. 100mL of ethylene glycol was added and ultrasonically dispersed for 0.5h. 33.5mg of chloroplatinic acid and 12mg of ferrous nitrate were dissolved in the ethylene glycol containing the carbon nanotubes and ultrasonically dispersed for 0.5h to achieve uniform mixing. The mixed solution was then heated to 80°C with stirring, and 500mL of a 0.1mol / L aqueous sodium borohydride solution was added. The reaction was continued for 3h. After the reaction, the mixed solution was filtered and separated, and the resulting solid was dried in a vacuum oven at 80°C for 12h. Finally, the dried solid was placed in a tube furnace, continuously purged with inert gas, and heated at a rate of 5°C / min to 650°C. The temperature was maintained for 1h, cooled to room temperature, and the resulting product, a carbon nanotube-supported platinum-iron alloy nanomaterial, was removed and designated PtFeC-4.

[0056] In the traditional process, reducing agents such as sodium borohydride and hydrogen are usually used to reduce platinum and iron ions to metallic states. However, sodium borohydride is a strong reducing agent, hydrogen is flammable and explosive, and the reduced platinum and iron are prone to agglomeration. Figure 1 This is the SEM result of the sample prepared in Example 1. It can be seen from the figure that the sample particles prepared by the method of the present invention have uniform particle size, the particle size is concentrated in the range of 200-300nm, and there is no obvious agglomeration and sintering phenomenon between the particles, and the dispersion is good. Further TEM results ( Figure 2 ) showed that the platinum-iron alloy sites were evenly distributed on the surface of the sample particles, with a particle size of about 5 nm, and there was no phenomenon of particle agglomeration and growth caused by high-temperature sintering.

[0057] Table 1 N2 adsorption and desorption test results of Example 1 and Comparative Example 1

[0058] catalyst <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Pore volume (cm 3 / g)]]> PtFeC-1 541.5 0.19 PtFeC-4 123.8 0.06

[0059] The nitrogen adsorption and desorption test results of Example 1 and Comparative Example 1 in Table 1 above show that the specific surface area of ​​Example 1 (541.5m 2 / g) was significantly higher than that of comparative example 1 (123.8m 2 / g), and high pore volume (0.19m 3 / g) is beneficial to the mass transfer and heat transfer process of the catalytic reaction, which can further promote the progress of the catalytic reaction. Figure 3 and Figure 4 As shown, the example samples showed a higher half-wave potential ( Figure 3 ), about 0.92V, representing a higher electrocatalytic efficiency; at the same time, the example sample has an obvious oxygen reduction reaction characteristic peak ( Figure 4 )( Figure 4 The cyclic voltammetry test conditions shown are: 10 mg of sample is dispersed in 1 mL of 5% Nafion-isopropanol solution, 5 microliters is dropwise applied to the surface of a glassy carbon electrode, and the sample is naturally dried before testing. The electrolyte is a 0.1 mol / L aqueous perchloric acid solution, the potential range is 0.05-1.281 V vs. RHE (reversible hydrogen electrode), and the scan rate is 0.02 V / s. The more obvious characteristic peaks also indicate that this material has good electrocatalytic activity for the oxygen reduction reaction. The electrochemical test results are also consistent with the TEM and nitrogen adsorption-desorption characterization results.

[0060] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims.

[0061] Any matters not described in detail in the present invention are well-known technologies to those skilled in the art.

Claims

1. A process for preparing a carbon-based platinum-iron alloy catalyst, characterized in that: The following steps are involved: S1. Prepare iron salt solution A; S2. Prepare an organic ligand solution B capable of binding iron ions and platinum ions, wherein the organic ligand is a bidentate ligand; S3. Prepare platinum salt solution C; S4. Prepare an organic ligand solution D that can bind iron ions but not platinum ions; S5. The iron salt solution A and the organic ligand solution B were mixed at room temperature and stirred to make the reaction uniform; S6. Platinum salt solution C was added to the mixed solution obtained in S5, and the mixed solution was heated and the reaction was fully carried out at a constant temperature, and the reaction temperature was controlled within the range of 40 to 60 ℃; S7. The organic ligand solution D is added to the mixed solution obtained in S6, and the mixed solution is heated to control the heating temperature of the mixed solution to 90 to 120 ° C, and the reaction time is controlled according to the desired particle size; S8. After the reaction is completed, the liquid in the mixture obtained in S7 is removed, the solid portion is washed with an aqueous ethanol solution, and then dried to obtain a powder; S9. Perform high-temperature alloying treatment on the powder to obtain a platinum-iron alloy catalyst.

2. The process for preparing a carbon-based platinum-iron alloy catalyst according to claim 1, wherein: The solute of the iron salt solution is one or more of ferric nitrate, ferric chloride, and ferric acetate, the solvent is pure water, and the concentration of iron ions in the solution is 0.05 to 0.5 mol / L; the solute of the platinum salt solution is one or more of chloroplatinic acid, potassium chloroplatinate, and sodium chloroplatinate, the solvent is pure water, and the concentration of platinum ions in the solution is 0.05 to 0.5 mol / L.

3. The process for preparing a carbon-based platinum-iron alloy catalyst according to claim 1, wherein: In step S2, the bidentate ligand in the organic ligand solution B is one or more of 2-methylimidazole, o-phenanthroline, and ethylenediamine, the solvent is one or more of methanol, ethanol, and propanol, and the concentration of the organic ligand in the solution is 0.1-1 mol / L.

4. The process for preparing a carbon-based platinum-iron alloy catalyst according to claim 1, wherein: In step S4, the organic ligand in the organic ligand solution D is benzoic acid and / or benzoic anhydride, the solvent is one or more of ethylene glycol, propylene glycol, and glycerol, and the concentration of the organic ligand in the solution is 0.1-1 mol / L.

5. The process for preparing a carbon-based platinum-iron alloy catalyst according to claim 1, characterized in that: In step S5, the reaction time is controlled within 1 to 3 hours; in step S6, the heating reaction time of the mixed solution is controlled within 4 to 6 hours; and in step S7, the reaction time is controlled within 8 to 12 hours.

6. The process for preparing a carbon-based platinum-iron alloy catalyst according to claim 1, characterized in that: In the step S8, the liquid in the mixture is removed by filtration; the volume fraction of ethanol in the ethanol aqueous solution is 50-70%, and the drying temperature is controlled at 60-80°C.

7. The process for preparing a carbon-based platinum-iron alloy catalyst according to claim 1, characterized in that: In step S9, the powder obtained in step S8 is spread on the bottom of the crucible, transferred to a tube furnace, and protected by nitrogen or inert gas, and subjected to high-temperature heat treatment at 300-800° C. for 1-3 hours.

8. A carbon-based platinum-iron alloy catalyst, characterized in that: The method is prepared by the preparation process according to any one of claims 1 to 7.

9. The carbon-based platinum-iron alloy catalyst according to claim 8, characterized in that: The particle size of the catalyst is 200-300 nm, the site size of the platinum-iron alloy is 4-8 nm, and the specific surface area is 500-600 m 2 / g, pore volume 0.15~0.25m 3 / g, half-wave potential 0.9~0.95V.

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