Preparation method of intermetallic compound electrocatalyst

Abstract

The embodiment of the invention discloses a preparation method of an intermetallic compound electrocatalyst, which comprises the following steps: adding a carbon carrier into a metal salt solution which is a solution formed by a mixture of platinum salt, ferric salt and tin salt, uniformly mixing, and then completely evaporating a solvent of the metal salt solution, so that the metal salt is adsorbed on the carbon carrier, a first intermediate product is obtained; carrying out annealing treatment on the first intermediate product to obtain a second intermediate product; the second intermediate product is subjected to acid pickling, drying and grinding treatment, and the carbon-supported platinum-iron intermetallic compound electrocatalyst is obtained. According to the preparation method of the intermetallic compound electrocatalyst, the low-melting-point tin is introduced, preparation of the intermetallic compound electrocatalyst can be achieved at the low annealing temperature, and the prepared electrocatalyst is high in activity and good in durability.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a method for preparing an intermetallic compound electrocatalyst. Background Art

[0002] In proton exchange membrane fuel cells (PEMFCs), the cathode oxygen reduction reaction (ORR) kinetics are relatively slow, which greatly reduces the efficiency of the battery. The current common solution in the industry is to use platinum-containing catalysts represented by platinum carbon (Pt / C) in the electrode. Although this solution solves the problem of slow ORR reaction kinetics to a certain extent, high cost, low activity and low durability still greatly hinder the large-scale application of PEMFCs.

[0003] Alloying is a solution to reduce costs and increase efficiency. The so-called alloying refers to the introduction of transition metals (Fe, Co, Ni) and Pt to form alloys, and the regulation of their composition and structure to improve the performance of the catalyst and reduce costs. However, disordered solid solution alloys will cause changes in the catalyst structure and even reduction in battery performance due to the dissolution of transition metal atoms in an acidic environment. Therefore, disordered solid solution alloys can be converted into ordered intermetallic compounds (IMCs). Because the crystal phase of intermetallic compounds is determined, the structure is ordered, and the catalytic active sites are evenly distributed, they have higher activity and stability. Platinum-iron intermetallic compounds are an ORR catalyst with excellent activity. The current preparation method is to perform a high-temperature annealing treatment of more than 700°C in a reducing atmosphere to overcome the atomic diffusion activation energy limitation of the alloy system, but it will cause the prepared IMC catalyst metal particles to sinter, change in morphology, and have high energy consumption.

[0004] Therefore, developing a method for preparing intermetallic compound electrocatalysts that can weaken the atomic diffusion activation energy limitation, realize the preparation of electrocatalysts at a lower annealing temperature, and improve the catalyst performance is an urgent problem to be solved in the field of proton exchange membrane fuel cell technology. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a method for preparing an intermetallic compound electrocatalyst, which can solve the problem of the current lack of a method for preparing an intermetallic compound electrocatalyst that can weaken the atomic diffusion activation energy limitation, realize the preparation of the electrocatalyst at a lower annealing temperature, and improve the catalyst performance.

[0006] The technical solutions provided by this application are as follows:

[0007] In one aspect, the present application provides a method for preparing an intermetallic compound electrocatalyst, the method for preparing the intermetallic compound electrocatalyst comprising:

[0008] Providing a carbon support and a metal salt solution, wherein the metal salt solution is a solution formed by a mixture of a platinum salt, an iron salt, and a tin salt;

[0009] Adding the carbon carrier to the metal salt solution, mixing evenly, and completely evaporating the solvent of the metal salt solution so that the metal salt is adsorbed on the carbon carrier to obtain a first intermediate product;

[0010] Annealing the first intermediate product to obtain a second intermediate product;

[0011] The second intermediate product is subjected to acid washing, drying and grinding treatment to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

[0012] In some optional embodiments, the platinum salt is at least one of chloroplatinic acid, platinum nitrate and sodium chloroplatinate, the iron salt is at least one of ferric chloride, ferrous chloride, ferrous sulfate and ferric nitrate, and the tin salt is at least one of stannous chloride, tin tetrachloride or stannous sulfate.

[0013] In some optional embodiments, the annealing treatment of the first intermediate product to obtain the second intermediate product comprises:

[0014] The first intermediate product is annealed in an atmosphere of a mixed gas so that the metal salt forms metal nanoparticles, and the carbon carrier with the metal nanoparticles is the second intermediate product.

[0015] In some optional embodiments, the mixed gas includes a protective gas and a reducing gas, and the volume fraction of the reducing gas in the mixed gas is 5%-15%.

[0016] In some optional embodiments, the protective gas is at least one of argon and nitrogen, and the reducing gas is hydrogen.

[0017] In some optional embodiments, the heating rate of the annealing treatment is 4°C / min-7°C / min, the holding temperature of the annealing treatment is 500°C-900°C, and the holding time of the annealing treatment is 2h-5h.

[0018] In some optional embodiments, the second intermediate product is subjected to acid washing, drying and grinding to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst, comprising:

[0019] Soaking the second intermediate product in an acid solution for 5 h to 10 h, and bathing in water at the same time, to obtain the second intermediate product after acid washing, wherein the temperature of the water bath is 40° C. to 70° C.;

[0020] The second intermediate product after acid washing is filtered, washed, dried and ground to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

[0021] In some optional embodiments, the acid solution is a sulfuric acid solution.

[0022] In some optional embodiments, the concentration of the sulfuric acid solution is 0.05M-0.2M.

[0023] On the other hand, the present application provides an intermetallic compound electrocatalyst, which is prepared by the preparation method described in any one of the above embodiments.

[0024] The preparation method of the intermetallic compound electrocatalyst provided in the present application comprises providing a carbon carrier and a metal salt solution, wherein the metal salt solution is a solution formed by a mixture of a platinum salt, an iron salt and a tin salt; adding the carbon carrier to the metal salt solution, mixing evenly, completely evaporating the solvent of the metal salt solution so that the metal salt is adsorbed on the carbon carrier to obtain a first intermediate product; annealing the first intermediate product to obtain a second intermediate product; pickling, drying and grinding the second intermediate product to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst. By introducing tin with a low melting point, the transformation from a disordered phase of a platinum-iron alloy to an ordered phase can be completed at a lower annealing temperature. The prepared intermetallic compound electrocatalyst has high activity and good durability, and the preparation method is simple, which can significantly reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 is a flow chart of a method for preparing an intermetallic compound electrocatalyst according to an embodiment of the present invention;

[0027] Figure 2 is the XRD spectrum of the electrocatalyst prepared according to an embodiment of the present invention and a comparative example;

[0028] Figure 3 1 is an LSV curve of the electrochemical activity test of the electrocatalyst prepared according to an embodiment of the present invention and a comparative example;

[0029] Figure 4 is a durability test result of an electrocatalyst prepared by a method for preparing an intermetallic compound electrocatalyst according to an embodiment of the present invention;

[0030] Figure 5 is the durability test result of the electrocatalyst prepared by the preparation method of the intermetallic compound electrocatalyst proposed in Comparative Example 1 of the present invention;

[0031] Figure 6 This is the durability test result of the electrocatalyst prepared by the preparation method of the intermetallic compound electrocatalyst proposed in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] The term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present application. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may include one or more of the features explicitly or implicitly. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0034] When a numerical range is disclosed herein, the above range is deemed to be continuous and includes the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges included therein. For example, a specified range from "1 to 10" should be deemed to include any and all sub-ranges between a minimum of 1 and a maximum of 10. Exemplary sub-ranges of ranges 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0035] Since there is currently a lack of a method for preparing an intermetallic compound electrocatalyst that can weaken the atomic diffusion activation energy limitation, achieve the preparation of the electrocatalyst at a lower annealing temperature, and improve the catalyst performance, therefore, in order to be able to weaken the atomic diffusion activation energy limitation, achieve the preparation of the electrocatalyst at a lower annealing temperature, and improve the catalyst performance, the present application provides a method for preparing an intermetallic compound electrocatalyst.

[0036] See also Figure 1 , Figure 1 The present invention provides a method for preparing an intermetallic compound electrocatalyst, and the method for preparing an intermetallic compound electrocatalyst comprises:

[0037] S101. Providing a carbon support and a metal salt solution, wherein the metal salt solution is a solution formed by a mixture of a platinum salt, an iron salt and a tin salt.

[0038] Optionally, the components of the catalyst include carrier carbon and an active substance, wherein the active substance refers to a platinum-iron intermetallic compound including a doping element tin.

[0039] Optionally, the mass percentage of the carbon carrier is 40%-80%.

[0040] Optionally, the specific surface area of ​​the carbon carrier is 600-2000m 2 / g, and the most probable pore size distribution is concentrated in the range of 2nm-5nm.

[0041] Optionally, the mass percentage of the active material is 20%-60%, wherein the atomic percentage of platinum is 40%-60%, the atomic percentage of iron is 25%-55%, and the atomic percentage of tin is 5%-15%.

[0042] Optionally, the particle size of the active substance ranges from 3nm to 6nm.

[0043] Optionally, the crystal structure of the active material matches the XRD standard PDF card PDF#65-1051.

[0044] Optionally, the model of the carbon carrier includes at least one of EC600J, EC300J, BP2000, MH-18, BMC-5, and BMC-8.

[0045] In an optional embodiment, the platinum salt is at least one of chloroplatinic acid, platinum nitrate and sodium chloroplatinate, the iron salt is at least one of ferric chloride, ferrous chloride, ferrous sulfate and ferric nitrate, and the tin salt is at least one of stannous chloride, tin tetrachloride or stannous sulfate.

[0046] By introducing tin with a low melting point, it can melt at a lower temperature and form alloys with other metals. During the catalyst preparation process, the introduction of tin can promote the interaction between platinum and iron at a lower annealing temperature to form intermetallic compounds, reduce thermal damage to the carbon carrier, maintain its structure and performance, and at the same time reduce energy consumption and reduce production costs.

[0047] S102. Add the carbon carrier to the metal salt solution, mix them evenly, and then completely evaporate the solvent of the metal salt solution so that the metal salt is adsorbed on the carbon carrier to obtain a first intermediate product.

[0048] Optionally, an ultrasonic stirrer or mechanical stirring can be used to help the carbon carrier to be evenly dispersed in the solution, and the metal salt ions will be adsorbed on the surface of the carbon carrier, and the carbon carrier adsorbed with the metal salt is the first intermediate product.

[0049] Optionally, the temperature for evaporating the solvent of the metal salt solution can be set according to actual business needs and is not limited here. Through the above steps, the metal salt can be effectively adsorbed on the carbon carrier, creating conditions for subsequent annealing treatment, and finally forming an intermetallic compound electrocatalyst.

[0050] S103. Annealing the first intermediate product to obtain a second intermediate product.

[0051] In an optional embodiment, the step of annealing the first intermediate product to obtain the second intermediate product comprises:

[0052] The first intermediate product is annealed in an atmosphere of a mixed gas so that the metal salt forms metal nanoparticles, and the carbon carrier with the metal nanoparticles is the second intermediate product.

[0053] In an optional embodiment, the mixed gas includes a protective gas and a reducing gas, and the volume fraction of the reducing gas in the mixed gas is 5%-15%.

[0054] In an optional embodiment, the protective gas is at least one of argon and nitrogen, and the reducing gas is hydrogen.

[0055] Optionally, the volume fraction of hydrogen in the mixed gas is 5%-15%, which can be set according to actual business needs and is not limited here. Exemplarily, the volume fraction of hydrogen in the hydrogen-argon mixed gas is 5%.

[0056] In an optional embodiment, the heating rate of the annealing treatment is 4°C / min-7°C / min, the holding temperature of the annealing treatment is 500°C-900°C, and the holding time of the annealing treatment is 2h-5h.

[0057] Optionally, the device for annealing in a hydrogen-argon mixed gas atmosphere is a tubular furnace, and the heating rate of the annealing treatment, the holding temperature of the annealing treatment, and the holding time of the annealing treatment can be set according to actual business needs and are not limited here. By way of example, the heating rate of the annealing treatment is 7°C / min, the holding temperature of the annealing treatment is 500°C, and the holding time of the annealing treatment is 2h. After the annealing treatment is completed, a second intermediate product is obtained.

[0058] Optionally, the first intermediate product is placed in a tubular furnace, and a hydrogen-argon mixed gas with a hydrogen volume fraction of 5% is introduced for annealing, the tubular furnace heating rate is 7°C / min, the insulation temperature is 500°C, the insulation time is 2h, and the second intermediate product is obtained after the annealing treatment. The carbon carrier adsorbed with the metal salt is annealed in an atmosphere of a hydrogen-argon mixed gas so that the metal salt is reduced to metal nanoparticles and fixed on the carbon carrier, and the carbon carrier with the metal nanoparticles is the second intermediate product.

[0059] The annealing process helps to reduce the metal salt, making the metal nanoparticles evenly dispersed on the carbon support, reducing the agglomeration of particles, increasing the specific surface area of ​​the electrocatalyst, and promoting the interaction between the metal nanoparticles and the carbon support, thereby improving the overall performance of the catalyst. Intermetallic compounds usually have unique electronic structures and surface properties, which can significantly improve the activity of electrocatalysts. Platinum-iron intermetallic compounds are more stable than single metal nanoparticles, have higher oxygen reduction reaction and hydrogen evolution reaction activity, and are more resistant to corrosion and agglomeration in electrocatalytic reactions, thereby improving the long-term stability of the catalyst.

[0060] S104. The second intermediate product is subjected to acid washing, drying and grinding treatment to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

[0061] In an optional embodiment, the second intermediate product is subjected to acid washing, drying and grinding to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst, comprising:

[0062] Soaking the second intermediate product in an acid solution for 5 h to 10 h, and bathing in water at the same time, to obtain the second intermediate product after acid washing, wherein the temperature of the water bath is 40° C. to 70° C.;

[0063] The second intermediate product after acid washing is filtered, washed, dried and ground to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

[0064] In an optional embodiment, the acid solution is a sulfuric acid solution.

[0065] In an optional embodiment, the concentration of the sulfuric acid solution is 0.05M-0.2M.

[0066] Optionally, the second intermediate product is immersed in a sulfuric acid solution for pickling and a water bath is performed at the same time. The concentration of the sulfuric acid solution, the pickling time, and the temperature of the water bath can be set according to actual business needs and are not limited here. For example, the second intermediate product is immersed in a 0.1M sulfuric acid solution for 7 hours and a water bath is performed at the same time, and the water bath temperature is maintained at 70°C.

[0067] Optionally, the device for filtration can be a Buchner funnel or a vacuum filtration device. The second intermediate product after acid washing is poured into the Buchner funnel or the vacuum filtration device, and appropriate filter paper and filter are used. The vacuum pump is turned on for filtration to separate the second intermediate product and the sulfuric acid washing solution.

[0068] Optionally, the solid product after suction filtration can be washed multiple times with deionized water or a suitable solvent to remove residual acid and soluble impurities.

[0069] Optionally, the washed solid product is transferred to a dryer, such as an oven or a vacuum drying oven, and dried at an appropriate temperature until the product is completely dry. The drying temperature can be set according to actual business needs and is not limited here. The grinding can be performed manually using a mortar and pestle to ultimately obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

[0070] By acid washing the second intermediate product, the surface of the catalyst can be cleaned, impurities on the catalyst surface and in the pores can be effectively removed, the pore structure can be optimized, the porosity and specific surface area of ​​the catalyst can be increased, and the diffusion and adsorption of the reactants can be facilitated. At the same time, acid washing can also help improve the dispersion of metal particles on the carbon carrier and reduce particle agglomeration, thereby improving the catalytic efficiency and stability of the catalyst.

[0071] The following is an overall description of the high temperature fuel cell catalyst preparation method provided in the embodiments of the present application:

[0072] Providing a carbon support and a metal salt solution, wherein the metal salt solution is a solution formed by a mixture of a platinum salt, an iron salt, and a tin salt;

[0073] Adding the carbon carrier to the metal salt solution, mixing evenly, and completely evaporating the solvent of the metal salt solution so that the metal salt is adsorbed on the carbon carrier to obtain a first intermediate product;

[0074] The first intermediate product is annealed in an atmosphere of a mixed gas so that the metal salt forms metal nanoparticles, and the carbon carrier with the metal nanoparticles is the second intermediate product.

[0075] The second intermediate product is immersed in an acid solution for 5h-10h and is bathed in water at the same time to obtain the second intermediate product after acid washing, wherein the temperature of the water bath is 40°C-70°C; the second intermediate product after acid washing is washed, dried and ground to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

[0076] Embodiment 1:

[0077] This embodiment provides a method for preparing an intermetallic compound electrocatalyst, and the specific preparation method is as follows:

[0078] Take 0.95mmoL of chloroplatinic acid, 0.76mmoL of ferric chloride and 0.19mmoL of stannous chloride respectively, add them into 60mL of ultrapure water and mix them evenly to obtain a metal salt solution;

[0079] 250 mg of a BMC-8 carbon carrier was added, and after being evenly mixed, the solvent of the metal salt solution was completely evaporated so that the metal salt was adsorbed on the carbon carrier to obtain a first intermediate product;

[0080] The first intermediate product is placed in a tubular furnace, and a hydrogen-argon mixed gas with a hydrogen volume fraction of 5% is introduced for annealing. The heating rate of the tubular furnace is 7°C / min, the holding temperature is 500°C, and the holding time is 2h. After the annealing treatment, a second intermediate product is obtained;

[0081] The second intermediate product is immersed in a 0.1M sulfuric acid solution for 7 hours, and at the same time, a water bath is placed, and the water bath temperature is maintained at 70°C. The second intermediate product after acid washing is filtered, washed, dried and ground to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

[0082] Comparative Example 1:

[0083] This comparative example provides an intermetallic compound electrocatalyst and a preparation method thereof, which is different from Example 1 in that no tin element is added and a higher temperature is required for annealing treatment.

[0084] The specific preparation method is as follows:

[0085] Take 0.95mmoL of chloroplatinic acid and 0.95mmoL of ferric chloride respectively, add them into 60mL of ultrapure water, mix and stir evenly to obtain a metal salt solution;

[0086] 250 mg of a BMC-8 carbon carrier was added, and after being evenly mixed, the solvent of the metal salt solution was completely evaporated so that the metal salt was adsorbed on the carbon carrier to obtain a first intermediate product;

[0087] The first intermediate product is placed in a tubular furnace, and a hydrogen-argon mixed gas with a hydrogen volume fraction of 5% is introduced for annealing. The heating rate of the tubular furnace is 7°C / min, the holding temperature is 800°C, and the holding time is 3h. After the annealing treatment, a second intermediate product is obtained;

[0088] The second intermediate product is immersed in a 0.1M sulfuric acid solution for 7 hours, and at the same time, a water bath is placed, and the water bath temperature is maintained at 70°C. The second intermediate product after acid washing is filtered, washed, dried and ground to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

[0089] Comparative Example 2:

[0090] This comparative example provides an intermetallic compound electrocatalyst and a preparation method thereof, which is different from comparative example 1 in that the annealing treatment used is 500°C.

[0091] The specific preparation method is as follows:

[0092] Take 0.95mmoL of chloroplatinic acid and 0.95mmoL of ferric chloride respectively, add them into 60mL of ultrapure water, mix and stir evenly to obtain a metal salt solution;

[0093] 250 mg of a BMC-8 carbon carrier was added, and after being evenly mixed, the solvent of the metal salt solution was completely evaporated so that the metal salt was adsorbed on the carbon carrier to obtain a first intermediate product;

[0094] The first intermediate product is placed in a tubular furnace, and a hydrogen-argon mixed gas with a hydrogen volume fraction of 5% is introduced for annealing. The heating rate of the tubular furnace is 7°C / min, the holding temperature is 500°C, and the holding time is 3h. After the annealing treatment, a second intermediate product is obtained;

[0095] The second intermediate product is immersed in a 0.1M sulfuric acid solution for 7 hours, and at the same time, a water bath is placed, and the water bath temperature is maintained at 70°C. The second intermediate product after acid washing is filtered, washed, dried and ground to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

[0096] The electrocatalysts prepared in Example 1 and Comparative Examples 1 and 2 were respectively prepared into slurries for electrochemical testing, and the specific method was as follows:

[0097] (1) Slurry preparation: Weigh 3.0 mg of the catalyst and add 0.5 mL of ultrapure water, 2.5 mL of isopropanol, and 10 μL of a 5% Nafion solution in sequence; then perform ultrasonic treatment to mix the slurry evenly. During the ultrasonic treatment, the water bath temperature must be kept below 20°C.

[0098] (2) Electrode preparation: The catalyst loading on the electrode surface is 50 μg / cm 2 , take an appropriate amount of the dispersed slurry and evenly drop it onto the smooth RDE electrode surface three times, dry it naturally, and use it as the working electrode;

[0099] (3) Electrochemical test: A three-electrode system was built, with a reversible hydrogen electrode as the reference electrode, a carbon rod as the counter electrode, and N as the electrolyte. 2 saturated 0.1M perchloric acid solution; then test the cyclic voltammetry curve, first activate the catalyst at a scan rate of 200mV / s, and then record the LSV curve at scan rates of 20mV / s and 10mV / s in the voltage range of 0V-1.2V relative to the reversible hydrogen electrode; finally, scan the voltage range of 0.6V-1.0V relative to the reversible hydrogen electrode at a scan rate of 100mV / s for 10,000 cycles and record the LSV curve again.

[0100] Please refer to Table 1, which is a comparison of the activity and durability of the catalysts prepared according to the preparation methods of Example 1, Comparative Example 1, and Comparative Example 2 in perchloric acid solution. It can be seen from the data in the table that the preparation method of the intermetallic compound electrocatalyst proposed in the present invention introduces low-melting-point tin to achieve the preparation of the platinum-iron intermetallic compound electrocatalyst at a lower annealing temperature, and the catalyst synthesized in Example 1 has higher catalyst activity and durability in the electrolyte than the intermetallic compound electrocatalyst prepared in Comparative Example 1 without introducing low-melting-point tin and the intermetallic compound electrocatalyst prepared in Comparative Example 2 without introducing low-melting-point tin and reducing the annealing temperature. It can be seen that the catalyst prepared by the preparation method of the intermetallic compound electrocatalyst proposed in the present invention has better quality activity and durability.

[0101] Table 1

[0102] Group Catalyst activity (mA / mg) Catalyst durability (decay rate) Example 1 830 3.6％ Comparative Example 1 630 6.2％ Comparative Example 2 370 29.7％

[0103] See also Figure 2 , Figure 2The XRD patterns of the electrocatalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 are shown in Figure 1. The horizontal axis of the XRD pattern represents the X-ray diffraction angle, and the vertical axis represents the standard diffraction intensity, that is, the intensity of the X-ray after being diffracted by the crystal at the diffraction angle. The intensity of the diffraction peak can reflect the order of the atomic arrangement in the crystal and estimate the relative content in the sample. As can be seen from the figure, there is no characteristic peak at about 33° in Comparative Example 2, and a characteristic peak appears after heating in Comparative Example 1. After tin is added to Example 1, a characteristic peak appears at 500°C, indicating that Sn doping reduces the atomic diffusion activation energy limit of the platinum-iron alloy to form an intermetallic compound, and the preparation of carbon-supported platinum-iron intermetallic compound electrocatalysts can be achieved at a lower temperature.

[0104] See also Figure 3 , Figure 3 The LSV curves are the electrochemical activity test curves of the electrocatalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2. The horizontal axis of the LSV curve represents the voltage applied to the electrode, and the vertical axis represents the corresponding current density. The potential at the start and end of the electrochemical reaction can be determined first. In this embodiment, the 0.8-1.0V voltage section is mainly used to evaluate the catalytic activity of the catalyst for a specific electrochemical reaction by observing the change in current density. As can be seen from the figure, the carbon-supported platinum-iron intermetallic compound electrocatalyst prepared by adding tin doping in Example 1 has a more uniform distribution of active sites and the highest catalytic activity.

[0105] See also Figure 4 , Figure 5 and Figure 6 , Figure 4 , Figure 5 and Figure 6 The durability test results of the electrocatalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 are respectively, Figure 4 , Figure 5 and Figure 6 The LSV curves of the two tests were recorded respectively. It can be found that the carbon-supported platinum-iron intermetallic compound electrocatalyst prepared by tin doping in Example 1 has an ordered structure and a higher bonding strength, so it is less likely to precipitate in an acidic environment and has the best durability.

[0106] In an optional embodiment, the present application proposes an intermetallic compound electrocatalyst, which is prepared by the preparation method described in any one of the above embodiments.

[0107] The preparation method of the intermetallic compound electrocatalyst provided in the present application comprises providing a carbon carrier and a metal salt solution, wherein the metal salt solution is a solution formed by a mixture of a platinum salt, an iron salt and a tin salt; adding the carbon carrier to the metal salt solution, mixing evenly, and completely evaporating the solvent of the metal salt solution so that the metal salt is adsorbed on the carbon carrier to obtain a first intermediate product; annealing the first intermediate product to obtain a second intermediate product; and pickling, drying and grinding the second intermediate product to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst. The preparation method of the intermetallic compound electrocatalyst provided in the present application has the following beneficial effects:

[0108] (1) By innovatively introducing tin with a low melting point, the preparation of platinum-iron intermetallic compound electrocatalysts can be achieved at a lower annealing temperature. The method is simple and the process is controllable, which can significantly reduce energy consumption and facilitate industrial large-scale production.

[0109] (2) The prepared platinum-iron intermetallic compound has a definite crystal phase, an ordered structure, and evenly distributed catalytic active sites, and possesses excellent electrocatalyst activity and durability.

[0110] The above description is only an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing an intermetallic compound electrocatalyst, characterized in that: The preparation method of the intermetallic compound electrocatalyst comprises: Providing a carbon support and a metal salt solution, wherein the metal salt solution is a solution formed by a mixture of a platinum salt, an iron salt, and a tin salt; Adding the carbon carrier to the metal salt solution, mixing evenly, and completely evaporating the solvent of the metal salt solution so that the metal salt is adsorbed on the carbon carrier to obtain a first intermediate product; Annealing the first intermediate product to obtain a second intermediate product; The second intermediate product is subjected to acid washing, drying and grinding treatment to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

2. The method for preparing the intermetallic compound electrocatalyst according to claim 1, characterized in that: The platinum salt is at least one of chloroplatinic acid, platinum nitrate and sodium chloroplatinate, the iron salt is at least one of ferric chloride, ferrous chloride, ferrous sulfate and ferric nitrate, and the tin salt is at least one of stannous chloride, tin tetrachloride or stannous sulfate.

3. The method for preparing the intermetallic compound electrocatalyst according to claim 1, characterized in that: The step of annealing the first intermediate product to obtain a second intermediate product comprises: The first intermediate product is annealed in an atmosphere of a mixed gas so that the metal salt forms metal nanoparticles, and the carbon carrier with the metal nanoparticles is the second intermediate product.

4. The method for preparing the intermetallic compound electrocatalyst according to claim 3, characterized in that: The mixed gas includes protective gas and reducing gas, and the volume fraction of the reducing gas in the mixed gas is 5%-15%.

5. The method for preparing the intermetallic compound electrocatalyst according to claim 4, characterized in that: The protective gas is at least one of argon and nitrogen, and the reducing gas is hydrogen.

6. The method for preparing the intermetallic compound electrocatalyst according to claim 3, characterized in that: The heating rate of the annealing treatment is 4°C / min-7°C / min, the holding temperature of the annealing treatment is 500°C-900°C, and the holding time of the annealing treatment is 2h-5h.

7. The method for preparing an intermetallic compound electrocatalyst according to claim 1, characterized in that: The second intermediate product is subjected to acid washing, drying and grinding to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst, comprising: Soaking the second intermediate product in an acid solution for 5 h to 10 h, and simultaneously performing a water bath to obtain the second intermediate product after acid washing, wherein the temperature of the water bath is 40° C. to 70° C.; The second intermediate product after acid washing is filtered, washed, dried and ground to obtain a carbon-supported platinum-iron intermetallic compound electrocatalyst.

8. The method for preparing the intermetallic compound electrocatalyst according to claim 7, characterized in that: The acid solution is a sulfuric acid solution.

9. The method for preparing an intermetallic compound electrocatalyst according to claim 8, characterized in that: The concentration of the sulfuric acid solution is 0.05M-0.2M.

10. An intermetallic compound electrocatalyst, characterized in that: The intermetallic compound electrocatalyst is prepared by the preparation method according to any one of claims 1 to 9.

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