High loading small size ptm / c intermetallics, method of making and use as hydrogen fuel cell cathode catalyst

Abstract

The application provides a high-loading small-size PtM / C intermetallic compound, a preparation method and an application as a hydrogen fuel cell cathode catalyst, a platinum source, an M metal source and L-cysteine hydrochloride are uniformly mixed in a solvent, the obtained solution is dropped onto carbon black for impregnation, and after rapid stirring and drying, a precursor is obtained; air calcination is performed; and argon-hydrogen reduction reduction calcination is performed, and the PtM / C intermetallic compound is obtained. Compared with the prior art, the application utilizes a medium-temperature slow heating strategy, simultaneously reduces the temperature and the heating rate of a reduction process, finds a temperature capable of providing sufficient energy to overcome an ordering energy barrier and slowly heats to provide sufficient time for an ordering process of an alloy. The PtM intermetallic compound exhibits excellent electrocatalytic performance, that is, can serve as a hydrogen fuel cell cathode catalyst, and exhibits very excellent electrocatalytic activity in a half-cell oxygen reduction reaction (ORR) and a single cell test, and the synthesis process is simple and has batch production potential.

Description

Technical Field

[0001] This invention belongs to the fields of inorganic nanomaterials and catalyst preparation research, specifically relating to a high-loading, small-size PtM / C intermetallic compound, its preparation method, and its application as a cathode catalyst for hydrogen fuel cells. Background Technology

[0002] Hydrogen fuel cells are used as energy conversion devices to utilize hydrogen energy, thereby reducing energy and environmental pressures. Hydrogen, as an energy carrier, undergoes an oxidation reaction at the anode to produce H₂. + Electrons diffuse through the proton exchange membrane to the cathode, and the generated electrons then form an electric current from the anode to the cathode through an external circuit, thus providing energy. This is in contrast to the 2e⁻ ions generated in the hydrogen oxidation reaction (HOR) at the anode. - In terms of process, the oxygen reduction reaction (ORR) at the cathode is more complex, involving 4e- - The multi-step coupling process exhibits sluggish kinetics and high overpotentials; therefore, improving the reaction kinetics of the ORR process is crucial for the development of proton exchange membrane fuel cells.

[0003] Pt-based catalysts have proven to be most effective for ORR (Organic Response) processes. However, pure Pt catalysts exhibit strong adsorption of oxygen-containing substances during ORR, and ORR performance is highly dependent on the electronic properties of the catalyst surface. Therefore, optimization of the catalyst's geometry and electronic structure is necessary to improve Pt utilization. Firstly, reducing the size of Pt-based catalysts exposes more active surface, thereby increasing activity; the catalyst particle size should be less than 5 nm. Secondly, alloying Pt with other transition metals can improve surface electronic structure and enhance catalytic performance. Intermetallic compounds (IMCs), also known as ordered alloys, possess near-surface atomic ordered structures and thermodynamic stability. However, the ordering process of alloys generally requires high temperatures to overcome the energy barrier of ordered atomic arrangement in the solid phase. High-temperature calcination often leads to catalyst particle agglomeration and Ostwald ripening, resulting in uneven catalyst particle size distribution. Therefore, it is necessary to find synthetic methods and conditions that simultaneously produce highly ordered and small-sized alloy nanoparticles under high-temperature conditions.

[0004] Furthermore, in practical applications, it is necessary to consider not only reducing the cost of catalyst fabrication but also ensuring its practical value. During the fabrication of membrane electrode assemblies (MEAs), to reduce the thickness of the catalyst layer and ensure good mass transfer along the metal conductive interface, the Pt metal loading is typically around 40 wt%-50 wt%. Because traditional methods often sacrifice metal loading to obtain smaller alloy catalysts at high temperatures, they are unsuitable for mass production applications.

[0005] Therefore, it is essential to provide a catalyst synthesis scheme with high loading, small size and high degree of order. Summary of the Invention

[0006] The purpose of this invention is to provide a high-load, small-size PtM / C intermetallic compound and its preparation method. The method involves a one-step impregnation and rapid drying process, followed by air calcination and slow, medium-temperature reduction with an argon-hydrogen mixture to obtain small-size carbon-supported PtM / C (M=Mn / Fe / Co / Ni, etc.) intermetallic compounds (IMCs) with different Pt loadings (40 wt%, 50 wt%, 60 wt%). This invention utilizes a one-step impregnation method combined with a slow heating strategy, resulting in a simple, efficient, and mass-production-ready preparation method.

[0007] Another objective of this invention is to provide an application of a high-loading, small-size PtM / C intermetallic compound as a cathode catalyst for hydrogen fuel cells. The materials of this invention exhibit excellent half-cell and single-cell performance, contributing to the development of fuel cell cathode catalysts.

[0008] The specific technical solution of this invention is as follows: A method for preparing a high-loading, small-size PtM / C intermetallic compound includes the following steps: 1) The platinum source, the M metal source and the L-cysteine ​​hydrochloride were mixed in a solvent, and the resulting solution was added dropwise onto carbon black for impregnation. After drying, the precursor was obtained. 2) The precursor is calcined in air; 3) The product after calcination in step 2) is subjected to argon-hydrogen atmosphere reduction calcination to obtain a high-loading, small-size PtM / C intermetallic compound.

[0009] In step 1), the molar ratio of the platinum source, the M metal source, and L-cysteine ​​hydrochloride is 1:1:2 - 3:1:6; preferably, the molar ratio of the platinum source, the M metal source, and L-cysteine ​​hydrochloride is 1:1:2. In step 1), the ratio of the platinum source to the solvent is 1.9 - 2.0 mmol / mL; In step 1), the platinum source is selected from soluble platinum salts, preferably chloroplatinic acid hexahydrate H2PtCl6•6H2O; In step 1), the solvent is deionized water; In step 1), the M metal source is selected from a transition metal source, preferably a Cu source, a Co source, or a Ni source; Furthermore, in step 1), the M metal source is a soluble transition metal salt, preferably a soluble transition metal nitrate; Preferably, the M metal source is selected from a Co source, and most preferably cobalt nitrate hexahydrate; In step 1), the carbon black is Ketjen black (EC600 JD) with a specific surface area of ​​1400 m². 2 / g.

[0010] In step 2), the air calcination process is carried out in a muffle furnace; In step 2), the air calcination specifically involves: a heating rate of 1-15℃ / min, heating to a calcination temperature of 200℃, and a calcination time of 1-6 h; In step 3), the argon-hydrogen atmosphere reduction calcination process is carried out in a tube furnace; In step 3), the hydrogen volume content in the argon-hydrogen atmosphere is 2-20%; In step 3), during the argon-hydrogen atmosphere reduction calcination, the heating rate is 2℃ / min, the temperature is raised to 700℃, and the calcination time is 2-15 h. This invention utilizes a simple one-step impregnation and two-step calcination process to prepare a practical catalyst with high metal loading, high order, small size, and high-quality activity. In the first step, impregnation, to ensure complete metal loading onto the carbon black, a high-concentration solution of chloroplatinic acid and cobalt nitrate is mixed and rapidly dried to completely evaporate the solvent water. The second step, air calcination, yields carbon-supported metal oxides, while a third step, argon-hydrogen calcination, reduces the metal.

[0011] This invention provides a high-loading, small-size PtM / C intermetallic compound, prepared using the method described above. The high-loading, small-size PtM / C intermetallic compound consists of metal nanoparticles supported on a carbon black surface, with a particle size of 2-5 nm. The Pt loading in the high-loading, small-size PtM / C intermetallic compound is 40 wt%-60 wt%, and the M metal is a transition metal source, preferably Cu, Co, or Ni.

[0012] This invention provides an application of a high-loading, small-size PtM / C intermetallic compound as a cathode catalyst for hydrogen fuel cells.

[0013] This invention employs a simple one-step synthesis strategy to obtain a series of highly loaded ordered alloy catalysts with sizes within 5 nm. Compared to traditional disordered solid solutions, atomically ordered Pt-IMC alloy catalysts exhibit higher activity and stability. However, their synthesis typically requires high-temperature annealing to overcome the energy barrier of atomic migration and ordering, leading to particle agglomeration. Therefore, finding a suitable calcination method to balance the contradiction between small catalyst size and high orderliness is crucial. This invention uses slow heating during calcination, employing a medium-temperature calcination of 700°C in the argon-hydrogen mixed gas stage. This provides energy to the alloy catalyst to overcome the ordering energy barrier while allowing sufficient time for atomic migration and rearrangement. Small-sized nanoparticle metal catalysts have high atomic utilization, but as the size of the metal nanoparticles decreases, the surface free energy of the metal increases, leading to a tendency for agglomeration. This makes balancing small catalyst size and high metal loading challenging. This invention utilizes a carbon support with a high specific surface area to prepare and reduce the catalyst at medium temperature, while avoiding particle agglomeration caused by high-temperature calcination by forming a complex between -SH in L-cysteine ​​hydrochloride and the metal.

[0014] Compared with existing technologies, the high-loading Pt-based IMCs nanocatalyst prepared in this invention can achieve a highly ordered alloy catalyst under the conditions of particle size less than 5 nm and Pt metal loading greater than 40%. Typically, the selected carbon support needs to possess high surface area, high electronic conductivity, and good resistance to chemical and electrochemical corrosion to ensure it can accommodate high metal loading, reduce voltage loss under high current density induced by ohmic impedance, and maintain good stability, thus exploring conditions for practical applications in fuel cells. This invention prepares an ordered PtM / C alloy catalyst, and the product, as a cathode catalyst in fuel cells, lowers the cathode reaction energy barrier and increases the power density of the cell. Attached Figure Description

[0015] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the carbon-supported metal oxide (product after air calcination) prepared in Example 1. Figure 2 The image shows the XRD pattern of the 40% PtCo / C ordered alloy prepared in Example 1. Figure 3 High-angle annular dark-field scanning transmission (HAADF-STEM) image of the 40% PtCo / C ordered alloy prepared in Example 1; Figure 4 Mapping diagram of the 40% PtCo / C ordered alloy prepared in Example 1; Figure 5 X-ray photoelectron spectroscopy (XPS) of the 40% PtCo / C ordered alloy prepared in Example 1. Figure 6 Thermogravimetric analysis (TG) diagram of the 40% PtCo / C ordered alloy prepared in Example 1; Figure 7 The graphs show the cyclic voltammetry (CV) and polarization curves (LSV) before and after the half-cell oxygen reduction 30 k accelerated durability test of the 40% PtCo / C ordered alloy prepared in Example 1. Figure 8 The power density curve of a single cell of the 50% PtCo / C ordered alloy prepared in Example 1 is shown. Figure 9 The XRD pattern of the 40% PtCo / C alloy prepared in Comparative Example 1; Figure 10 The XRD pattern of the 40% PtCo / C alloy prepared in Comparative Example 2; Figure 11 The XRD pattern of the 40% PtCo / C alloy prepared in Comparative Example 3; Figure 12 XRD patterns of the 40% PtCu / C and 40% PtNi / C alloys prepared in Comparative Example 4; Figure 13 For comparison example 4, cyclic voltammetry (CV) and polarization curve (LSV) plots of 40% PtCu / C were prepared; Figure 14 For comparison example 4, cyclic voltammetry (CV) and polarization curve (LSV) plots of 40% PtNi / C were prepared; Figure 15 The image shows the XRD pattern of the 50% PtCo / C ordered alloy prepared in Example 1. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0018] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0019] The calcination equipment of this invention includes a muffle furnace (GMF-1100X—Hefei Kejing) and a tube furnace (OTF-1200X—Hefei Kejing). The carbon black used is Ketjen black (EC600 JD) with a specific surface area of ​​1400 m². 2 / g. Example

[0020] A method for preparing a high-loading, small-size PtM / C intermetallic compound includes the following steps: 1) Preparation of precursor: Chloroplatinic acid hexahydrate, cobalt nitrate hexahydrate and 0.1882 g L-cysteine ​​hydrochloride were mixed in water and ultrasonically mixed to obtain a mixed solution. The molar ratio of chloroplatinic acid hexahydrate, cobalt nitrate hexahydrate and L-cysteine ​​hydrochloride was 1:1:2 and the volume ratio of chloroplatinic acid hexahydrate to water was 2.0 mmol / mL. The resulting mixed solution was impregnated with 0.1 g carbon black and stirred to allow the solvent to evaporate naturally and dry, to obtain a 40 wt% PtCo / C precursor. 2) Air calcination: The precursor obtained after impregnation is placed in a muffle furnace and heated to 200°C at a rate of 2°C / min under an air atmosphere. It is then calcined at this temperature for 2 h to obtain carbon-supported metal oxide. 3) Argon-hydrogen mixed gas reduction: The product after air calcination is passed into a tube furnace with a hydrogen volume content of 10% H2 / Ar mixed gas, and the temperature is raised to 700℃ at 2℃ / min for 2 h for reduction. The product is then naturally cooled to obtain the final product, which is a 40 wt% PtCo / C alloy.

[0021] The calculation method for a loading capacity of 40 wt% is based on the theoretical calculation of the amount of raw materials input: Loading weight = [mPt / (mC+mPt+mCo)]×100%; where mPt is the mass of Pt in the raw materials, mC is the mass of carbon black in the raw materials, and mCo is the mass of Co in the raw materials, all in grams. Based on the above feeding calculation, the loading weight = 44.23%, which is defined in this invention as a 40 wt% PtCo / C alloy.

[0022] The 40 wt% PtCo / C alloy obtained according to the above preparation method was analyzed by X-ray diffraction (XRD). Figure 1 The amorphous structure was determined to be obtained during the air calcination stage, and XRD was performed after argon-hydrogen reduction. Figure 2 Phase analysis revealed an ordered alloy catalyst based on the presence of superlattice peaks, and the nanoparticle size was preliminarily calculated to be approximately 2.3 nm using the Scherrer equation. High-angle annular dark-field scanning transmission electron microscopy was then performed. Figure 3 The ordered arrangement of the two metals was observed, and the size distribution of the metal nanoparticles was statistically analyzed and compared with the XRD results. Figure 4The alloy's mapping diagram shows that Pt and Co elements are uniformly distributed in the same region. Then, through... Figure 5 X-ray photoelectron spectroscopy further confirmed that the surface of the alloy catalyst contained almost no Cl, and Pt and Co existed in an alloy form. Finally, thermogravimetric analysis (TGA) curves... Figure 6 The total metal content was obtained, and combined with the ICP results, the ratio of Pt to Co in the catalyst was determined to be 1:1. The thermogravimetric (TG) curve and thermogravimetric differential (DTG) curve were obtained under the following experimental conditions: air, 10℃ / min, 25℃-800℃.

[0023] Following the same method as in Example 1, the amount of raw materials was changed, specifically as follows: Chloroplatinic acid hexahydrate, cobalt nitrate hexahydrate, and 0.2751 g of L-cysteine ​​hydrochloride were mixed in water and ultrasonically mixed to obtain a mixed solution. The molar ratio of chloroplatinic acid hexahydrate, cobalt nitrate hexahydrate, and L-cysteine ​​hydrochloride was 1:1:2, and the volume ratio of chloroplatinic acid hexahydrate to water was 2.0 mmol / mL. The resulting mixed solution was impregnated with 0.1 g of carbon black and stirred until the solvent evaporated naturally to obtain a 50 wt% PtCo / C precursor. A 50 wt% PtCo / C alloy was obtained. Subsequent air calcination and argon-hydrogen mixed gas reduction were performed according to Example 1 above to obtain a 50 wt% PtCo / C alloy. Based on the above feed calculation, the loading was 51.08%, and this invention defines it as a 50 wt% PtCo / C alloy.

[0024] Comparative Example 1 The procedure was carried out according to Example 1, except that the heating rate was changed to 1°C / min, 5°C / min, and 10°C / min during the reduction process at 700°C. The XRD results were obtained. Figure 9 Observing the changes in the superlattice peaks, at 1℃ / min, 5℃ / min, and 10℃ / min, there was no peak at 31.3 degrees, so the ordered structure of the present invention could not be obtained. Therefore, the present invention prepared the structure by controlling the heating rate to 2℃ / min.

[0025] Comparative Example 2 The procedure was carried out according to Example 1, except that the calcination temperature was changed to 600°C, 800°C, and 900°C during the high-temperature reduction process. XRD analysis was performed. Figure 10 The changes in the full width at half maximum (FWHM) of the superlattice peak and diffraction peak were observed. With increasing calcination temperature, the FWHM of the catalyst XRD pattern gradually narrowed, corresponding to an increase in the size of the alloy nanoparticles. The superlattice peak near 31.3 degrees gradually strengthened, corresponding to an increase in the alloy's order. Higher temperatures and increased alloy nanoparticle size imply Pt agglomeration, leading to a reduction in exposed metal surface area and catalytic active sites. This is detrimental to obtaining high mass activity and active area, resulting in low noble metal utilization. Therefore, this invention controls the temperature at 700 °C.

[0026] Comparative Example 3 The procedure was carried out according to Example 1, except that the molar ratio of Pt and Co in the precursor was changed to 1:3 and 3:1, followed by air calcination and high-temperature reduction with argon-hydrogen gas. The XRD results were obtained. Figure 11 Observe the changes in the superlattice peaks. The ratio of Pt to Co affects the degree of alloying and the formation of ordered alloys during the synthesis of intermetallic compounds. Figure 11 As the proportion of Co increases, the alloy peak position in XRD shifts to the right from Pt3Co (41.46) and PtCo (41.54) to PtCo3 (42.45), indicating that the degree of alloying increases with the increase of Co content. However, no superlattice peak (31.3 degrees) representing an ordered structure appears in the XRD pattern of PtCo3, indicating that the formation of ordered alloys requires a specific metal ratio (molar ratio Pt:Co = 1:1 and 3:1).

[0027] Comparative Example 4 Following Example 1, only the Co source in the precursor was replaced with equimolar amounts of Cu and Ni sources, followed by air calcination and high-temperature reduction with argon-hydrogen gas. The resulting products were defined as 40% PtCu / C and 40% PtNi / C catalysts, respectively. XRD patterns are shown below. Figure 12 As shown, the product grain size is all within 5 nm. Therefore, replacing the metal source with a Co source or a Cu source can still achieve the preparation of the small-sized products of this invention.

[0028] Application Example 1 The application of the high-loading, small-size PtM / C intermetallic compound provided by this invention in the half-reaction of a hydrogen fuel cell is specifically described as follows: The electrochemical workstation (CHI 760e) was used at a controlled temperature of 25°C. The 40% PtCo / C and 50% PtCo / C catalysts prepared in Example 1 were etched in 0.5 M H₂SO₄ at 90°C for 6 h before electrochemical testing (to remove surface Co metal and expose more Pt sites, while simultaneously regulating the changes in the surface electronic and lattice structures of Pt, which is beneficial for improving catalytic activity). They were then washed with deionized water and dried in a 60°C oven for later use. A rotating disk electrode (RDE), i.e., a glassy carbon electrode with a diameter of 5 mm, was used as the working electrode. A Hg / Hg₂SO₄ electrode (saturated with K₂SO₄) and a Pt sheet (5 mm × 5 mm) electrode were used as the reference and counter electrodes, respectively. The Hg / Hg₂SO₄ was calibrated in H₂-saturated 0.1 M HClO₄. All reference potentials were converted to reversible hydrogen electrode (RHE). The preparation of the working electrode required the catalyst to be prepared as ink and drop-coated onto the surface of a platinum-carbon electrode. Isopropanol and Nafion (5 wt%, D520) solutions were mixed with the catalyst and ultrasonically mixed to prepare an ink with a catalyst concentration of 2 mg / mL. The resulting ink was then used at a concentration of 15 µg. Pt / cm 2 The catalyst was loaded and drop-coated onto a disk electrode, then allowed to air dry to obtain a uniform thin-film electrode. All cyclic voltammetry (CV) and oxygen reduction polarization (LSV) curves were recorded in 0.1 M HClO4 at 0.05–1.05 V (vs. RHE). Cyclic voltammetry (CV) scans were performed at 250 mV / s in N2-saturated 0.1 M HClO4 solution to electrochemically activate the catalyst for a certain number of cycles. The capacitance current and electrochemical active area (ECSA) were then recorded at 10 mV / s and 50 mV / s, respectively. Linear sweep voltammetry (LSV) curves were then obtained in O2-saturated 0.1 M HClO4 at an initial potential of 0.05 V, at 1600 rpm and 10 mV / s. The final performance was obtained after correcting for capacitance current and solution resistance. The stability of the catalyst was tested and characterized by accelerated durability testing (ADT) in O2-saturated 0.1 M HClO4 solution. Cyclic testing was performed within the range of 0.6 to 1.05 V (vs. RHE) at a scan rate of 250 mV / s, with O2 continuously supplied during the test. After the test, the CV curve and ORR polarization curve after ADT were recorded.

[0029] The prepared 40% PtCo / C catalyst exhibited a mass activity (MA) of 0.682 A / mg in 0.1 M HClO4 electrolyte during half-cell RDE testing. Pt(0.9 V vs. RHE), active surface area (ECSA) is 73.3 m². 2 / g Pt The specific activity (SA) was 0.930 mA / cm³. 2 The catalyst initially exhibited excellent oxygen reduction catalytic activity. After accelerated durability testing (ADT) of the 40% PtCo / C catalyst obtained in this invention, the ECSA decreased by only 13%, and the MA decreased by only 30%. The mass activity (MA) of the 40% PtCu / C and 40% PtNi / C catalysts were 0.389 A / mg. Pt (0.9 V vs. RHE) and 0.286 A / mg Pt The active surface area (ECSA) is 86.1 m². 2 / g Pt and 83.3 m 2 / g Pt The specific activity (SA) is 0.451 mA / cm. 2 and 0.344 mA / cm 2 It initially showed good oxygen reduction catalytic activity. Figure 7 The figures show the cyclic voltammetry (CV) and polarization curves (LSV) of the 40% PtCo / C ordered alloy prepared in Example 1 before and after the half-cell oxygen reduction 30 k accelerated durability test. Initial represents the initial activity, and 30 k ADT represents the activity after 30,000 cycles of accelerated durability test.

[0030] Application Example 2 The application of the high-loading, small-size PtM / C intermetallic compound provided by this invention in the half-reaction of hydrogen fuel cells is specifically as follows: Method: A uniformly dispersed ink was prepared by adding 50% PtCo / C catalyst to deionized water, isopropanol, and Nafion (D2020). The ink was then sprayed onto an active area of ​​25 cm² using an ultrasonic spraying method (XF-100). 2 The catalyst was applied to a Nafion membrane (Gore; 12 µm). The anode used was commercial PtC; the cathode was the PtCo IMCs catalyst and TKK (TEC36F52) provided in this invention, with a loading of 0.2 g. Pt / cm 2 Catalyst-coated membranes (CCMs) were prepared. Nonwoven carbon paper (Sigracet 22BB) with microporous layers was used as the gas diffusion layer (GDL) for both the anode and cathode. The performance of the MEA was evaluated using a Skribna 850e potentiostat. H2-air tests were performed at 80 °C, 100% RH, 150 kPa, and 1 / 4 L / min. -1 .

[0031] The PtCo IMCs catalyst further exhibited excellent performance in the membrane electrode assembly (MEA) assembled from a single cell. Under the test conditions of light-duty hydrogen fuel cell transportation (LDV; 80°C, 100% RH, 150 kPaabs), the cathode loading was 0.16 g. Pt / cm -2 The catalyst obtained by this invention achieves a current density of 1.6 A / cm² at a voltage of 0.65 V. -2 Peak power density reaches 1.5 W / cm² -2 In contrast, the commercial TANAKA (TEC36F52) with the same load capacity has a current density of only 1.2 A / cm². -2 and 0.9 W / cm -2 .

[0032] This invention utilizes a slow, moderate-temperature heating strategy, simultaneously reducing the temperature and heating rate of the reduction process. This allows for the identification of a temperature that provides sufficient energy to overcome the ordering barrier, while the slow heating provides ample time for the alloy's ordering process. PtM intermetallic compounds exhibit excellent electrocatalytic performance, making them suitable as cathode catalysts in hydrogen fuel cells. They demonstrate outstanding electrocatalytic activity in both half-cell oxygen reduction reaction (ORR) and single-cell tests. The synthesis process is simple and possesses the potential for mass production.

[0033] The above description of the embodiments is intended to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a high-loading, small-size PtM / C intermetallic compound, characterized in that, The preparation method includes the following steps: 1) The platinum source, the M metal source and the L-cysteine ​​hydrochloride were mixed in a solvent, and the resulting solution was added dropwise onto carbon black for impregnation. After drying, the precursor was obtained. 2) The precursor is calcined in air; 3) The product after calcination in step 2) is subjected to argon-hydrogen atmosphere reduction calcination to obtain a high-loading, small-size PtM / C intermetallic compound; In step 3), the hydrogen volume content in the argon-hydrogen gas is 2-20%; the heating rate is 2℃ / min, the temperature is raised to the calcination temperature of 700℃; and the calcination time is 2-15 h. The high-loading, small-size PtM / C intermetallic compound consists of metal nanoparticles loaded on the surface of carbon black, with a particle size of 2-5 nm; the Pt loading in the high-loading, small-size PtM / C intermetallic compound is 40 wt%-60 wt%.

2. The preparation method according to claim 1, characterized in that, In step 1), the molar ratio of the platinum source, the M metal source, and the L-cysteine ​​hydrochloride is 1:1:2 - 3:1:

6.

3. The preparation method according to claim 1 or 2, characterized in that, In step 1), the ratio of the platinum source to the solvent is 1.9 - 2.0 mmol / mL.

4. The preparation method according to claim 1 or 2, characterized in that, In step 1), the M metal source is selected from a transition metal source.

5. The preparation method according to claim 1 or 2, characterized in that, In step 1), the platinum source is selected from soluble platinum salts.

6. The preparation method according to claim 1, characterized in that, In step 1), the solvent is deionized water.

7. The preparation method according to claim 1, characterized in that, In step 2), the heating rate is 1-15℃ / min, and the temperature is raised to the calcination temperature of 200℃; the calcination time is 1-6 h.

8. A high-loading, small-size PtM / C intermetallic compound prepared by the preparation method according to any one of claims 1-7, wherein the Pt loading is 40 wt%-60 wt%, and the M metal is a transition metal source, namely Mn, Fe, Co, or Ni.

9. An application of the high-loading, small-size PtM / C intermetallic compound of claim 8, characterized in that, Applications as cathode catalysts in hydrogen fuel cells.

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