A method for improving the interaction between noble metal nanoparticles and carbon support and applications thereof

Abstract

The application discloses a method for improving interaction between noble metal nanoparticles and carbon carriers and application thereof, and relates to the technical field of fuel cell catalysts, and comprises the following steps: synthesizing transition metal carbides with stable structures by using transition metal elements; supporting the synthesized transition metal carbides on the carrier carbon, and preliminarily establishing local order between the transition metal carbides and the carbon carriers; in-situ reducing noble metal precursors, and meanwhile, reserving at least one layer of metal carbide structures between the noble metal nanoparticles and the carbon carriers; establishing direct local bonding relationship between the metal carbide structures and the carbon carriers, and completing the construction of strong interaction between the noble metal particles and the carbon carriers. The method can relieve the problems of movement and falling of the noble metal nanoparticles on the surface of the carbon carriers under actual working conditions, so as to improve the stability of the fuel cell catalysts.

Description

Technical Field

[0001] This invention relates to the field of fuel cell catalyst technology, specifically to a method and application for improving the interaction between noble metal nanoparticles and carbon supports. Background Technology

[0002] Hydrogen-oxygen fuel cells, as an energy conversion device, can directly convert the chemical energy stored in hydrogen and oxygen into electrical energy under low-temperature conditions. They are characterized by being clean and pollution-free, with high energy conversion efficiency, and are of great significance in mitigating environmental pollution caused by fossil fuels and effectively reducing human dependence on them. Currently, the bottlenecks restricting the development of fuel cells are mainly cost and lifespan. Reflecting on the specific battery structure and process, this primarily involves the oxygen reduction reaction occurring at the complex three-phase interface of the cathode. This involves oxygen molecules transported by the pores of the gas diffused electrode layer (GDL) and catalyst layer, electrons conducted by the electrode and carbon (C) support, and protons conducted by the proton exchange membrane (PEM) and ionomer film, all reacting on the catalyst surface to produce water. The slow kinetics of this reaction necessitate the use of expensive platinum (Pt) as a catalyst. Simultaneously, under oxygen and high-potential environments, the catalytic centers composed of Pt nanoparticles, carbon support, and ionomers undergo structural damage, leading to a reduction in the overall battery lifespan. Over the past few decades, the industry has made groundbreaking progress in improving the intrinsic activity of Pt nanoparticles and suppressing the oxidation of carbon supports. In particular, the intrinsic activity of Pt nanoparticles has been improved by orders of magnitude in half-cells, which is significant for reducing the loading of precious metals in the catalyst layer and the overall cost of the battery. However, regarding the stability of hydrogen-oxygen fuel cells, many issues still need to be overcome and validated before large-scale commercialization.

[0003] Specifically, breaking down the Pt nanoparticles and carbon support structural units, besides the aforementioned oxidation of the carbon support, the reasons for insufficient stability mainly include three aspects: First, when the size distribution of Pt nanoparticles is relatively large, the equilibrium Pt ion concentration on the surface of nanoparticles of different sizes is different, resulting in the dissolution of small particles and the growth of large particles (Ostwald ripening) under actual working conditions; Second, atoms located at the vertices and crystal edges of the Pt nanoparticle surface have high coordination unsaturation, and these high-energy atoms will dissolve at high potentials, resulting in the loss of active sites; Third, when the interaction between Pt particles and the carbon support is relatively weak, Pt particles will move on the surface of the carbon support under actual working conditions, resulting in the connection, coarsening, and detachment of Pt particles from the carbon support surface, causing a loss of effective active area.

[0004] Previous research and patents have shown that improving the monodispersity of Pt nanoparticles can effectively alleviate the coarsening problem caused by the Ostwald ripening phenomenon. Regarding the dissolution of atoms with high coordination unsaturation, this phenomenon can be mitigated when the Pt nanoparticles are small in size and nearly spherical in shape. However, for the third problem, since carbon supports are relatively inert and their cell parameters and crystal symmetry differ significantly from those of Pt nanoparticles, establishing a strong interaction between them is quite difficult. Therefore, the loss of effective active area due to the migration and shedding of Pt particles, especially for catalysts with small Pt particle sizes, is a key factor in the overall stability degradation of fuel cells. Enhancing the interaction between carbon supports and Pt particles is the core scientific problem for mitigating this phenomenon.

[0005] Based on the above, no relevant literature has yet disclosed a corresponding solution. Therefore, developing a method to improve the interaction between noble metal nanoparticles and carbon supports is of great significance for solving key problems in the industry and promoting the large-scale commercialization of fuel cells. Summary of the Invention

[0006] Given the current problem of fuel cell catalysts experiencing a loss of effective active area due to the movement and shedding of Pt particles, which leads to a decrease in fuel cell stability, the present invention aims to provide a method and application for improving the interaction between noble metal nanoparticles and carbon supports. This method can alleviate the problem of noble metal nanoparticles moving and shedding from the surface of carbon supports under actual operating conditions, thereby improving the stability of fuel cell catalysts.

[0007] This invention is achieved through the following technical solution:

[0008] In a first aspect, this application provides a method for improving the interaction between noble metal nanoparticles and carbon supports, comprising the following steps:

[0009] Synthesize structurally stable transition metal carbides using transition metal elements;

[0010] The synthesized transition metal carbides were loaded onto a carbon support, and the local order between the transition metal carbides and the carbon support was initially established.

[0011] In-situ reduction of noble metal precursors is performed while retaining at least one layer of metal carbide structure between the noble metal nanoparticles and the carbon support.

[0012] A direct local bond relationship was established between the metal carbide structure and the carbon support, thus completing the construction of strong interactions between noble metal particles and carbon support.

[0013] This method, starting from the crystal structure, symmetry, and corresponding stability of carbides formed by carbon atoms and metal atoms, identifies the optimal carbon atom embedding pore type (tetrahedral or octahedral) and embedding quantity. This forms the basis for a stable "bridge" structure between Pt nanoparticles and the carbon support in the fuel cell catalyst layer—namely, transition metal carbides. Based on the difference in standard reduction electrode potential between transition metals and Pt ions, the heterogeneous nucleation and growth process of Pt nanoparticles is controlled, allowing Pt particles to grow in situ on the surface of transition metal carbides. Simultaneously, one to several layers of carbides are retained between the carbon support and Pt particles to enhance the interaction between them, thereby improving the stability of small-sized Pt particles on the carbon support. Building upon the synthesis in the first two steps, a precise post-processing procedure enables the controllable precipitation of carbon atoms from the carbides, forming a locally ordered structure with the carbon atoms of the support. This provides a solution to the key issues currently hindering the development of fuel cells.

[0014] In one specific embodiment, the transition metal element includes any one of iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), chromium (Cr), manganese (Mn), and zinc (Zn). Iron (Fe), cobalt (Co), nickel (Ni), and manganese (Mn) are preferred.

[0015] In one specific embodiment, during the construction of the transition metal carbide, the carbon atoms are positioned in tetrahedral or octahedral positions within the interstitial sites of the transition metal. The preferred insertion position is the octahedral position, which has a larger radius, facilitating the entry and exit of carbon atoms.

[0016] In one specific embodiment, during the construction of the transition metal carbide, the molar ratio of carbon atom insertion is controlled between 15% and 100%, preferably 25%.

[0017] In one specific embodiment, during the in-situ reduction of the noble metal precursor, the ligands selected from the noble metal precursor are acetylacetone, Cl ions, and NH2. - It can be any one of oxalate, NH3, etc. Acetylacetone is preferred due to its strong coordination ability, which can effectively avoid homogeneous nucleation during the in-situ deposition of noble metal atoms.

[0018] In one specific embodiment, the temperature during the in-situ reduction of the noble metal precursor is controlled at 120℃ to 150℃. Taking platinum acetylacetonate as a precursor as an example, while ensuring the reaction rate, the temperature of the noble metal deposition process should be as low as possible, preferably controlled at 120℃ to 150℃, which can effectively avoid homogeneous nucleation during the in-situ deposition of noble metal atoms.

[0019] In a specific embodiment, when the noble metal precursor is reduced in situ, the noble metal precursor solution is added dropwise. Taking platinum acetylacetonate as a precursor as an example, while ensuring the reaction rate, the dropping rate of the noble metal precursor should be as slow as possible, preferably dropwise, which can effectively avoid homogeneous nucleation during the in-situ deposition of noble metal atoms.

[0020] In one specific embodiment, when the noble metal precursor is reduced in situ, the molar ratio of the noble metal to the transition metal element is controlled at 1:(0.8-0.95). Taking platinum acetylacetonate as a precursor as an example, the molar ratio of Pt to the transition metal Ni is controlled between 1:0.8-0.95, preferably 0.85, which ensures that a structure of 1-5 carbide layers is retained between the carbon support and the Pt particles.

[0021] In a specific embodiment, when establishing a direct local bond between the metal carbide structure and the carbon support, a heat treatment method is used, with the temperature controlled between 300°C and 500°C. Taking a carbon-supported Pt catalyst as an example, the treatment temperature is controlled within the range of 300-500°C, preferably 350°C. This effectively controls the precipitation of carbon atoms while allowing the precipitated carbon atoms to establish a short-range ordered bond with the carbon atoms on the support.

[0022] Secondly, this application provides a fuel cell catalyst in which the above-mentioned method is used to enhance the interaction between noble metal nanoparticles and carbon support during the preparation of the fuel cell catalyst.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] (1) This invention starts from the perspective of the crystal structure, symmetry and corresponding stability of carbon atoms and metal atoms forming carbides, finds the optimal carbon atom insertion pore type (tetrahedral or octahedral) and insertion number, and forms the basis of a stable "bridge" structure between noble metal nanoparticles and carbon support in fuel cell catalyst layer, namely transition metal carbides.

[0025] (2) Based on the difference in standard reduction electrode potential between transition metal and noble metal ions, this invention regulates the heterogeneous nucleation and growth process of noble metal nanoparticles, grows noble metal particles in situ on the surface of transition metal carbides, and retains one to several layers of carbide structure between the carbon support and the noble metal particles to enhance the interaction between the carbon support and the noble metal particles, thereby improving the stability of small-sized noble metal particles on the carbon support.

[0026] (3) This invention enables the controllable precipitation of carbon atoms in carbides and forms a locally ordered structure with the carbon atoms of the carrier, providing a solution to the key problems that currently restrict the development of fuel cells.

[0027] (4) Compared with commercial catalysts, the catalyst prepared by the method of the present invention has a voltage decay of only 20% to 30% of that of commercial catalysts in the full current density range before and after low potential durability testing, and the retention rate of electrochemical active area and mass activity are higher than those of commercial catalysts. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0029] Figure 1 This is a schematic diagram illustrating the design principle and overall process flow of the present invention;

[0030] Figure 2 These are the physical property characterization diagrams of the carbide prepared in Example 1 of the present invention, wherein (a) and (b) are transmission electron microscopy (TEM) images, (c) is a selected area electron diffraction (SED) pattern, and (d) is an X-ray diffraction (XRD) pattern.

[0031] Figure 3 This is a TEM image of the Pt / C catalyst prepared in Example 1 of the present invention;

[0032] Figure 4 The graph shows the performance characteristics of a single cell of the Pt / C catalyst prepared in Example 1 of this invention and a single cell of the commercially available Tanaka Noble Metals Pt / C catalyst in Comparative Example 1.

[0033] Figure 5 This is a comparison chart of the durability data of the Pt / C catalysts prepared in Examples 2-10 of this invention before and after. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0035] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0036] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0037] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0038] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0039] like Figure 1 As shown, this invention improves the interaction between carbon atoms and noble metal atoms (including but not limited to Pt, Pd, Rh, Ir, etc.) by systematically constructing a bridge structure in which "closely packed metal atoms form the basic framework and carbon atoms are embedded in the corresponding interstitial positions," thereby enhancing the stability of carbon-supported platinum catalysts under actual working conditions.

[0040] The specific steps are as follows:

[0041] Step 1: Using Ni, Co, Fe, Mn, Zn, etc., as transition metal elements, stable transition metal carbides were synthesized through different synthetic systems, including but not limited to organic amine systems (oleylamine, aniline, octadecene, etc.), polyol systems (ethylene glycol, glycerol, etc.), and water systems. The insertion sites and contents of carbon atoms were confirmed by X-ray diffraction, transmission electron microscopy, low-frequency Raman spectroscopy, and elemental analysis. The structural stability of the carbides was determined by in-situ X-ray diffraction under an inert atmosphere.

[0042] Step 2: The synthesized Co, Ni and other carbides are loaded onto the carbon support through methods such as ultrasonication, shearing and ball milling, and the local order between the carbides and the carbon support is initially established through post-processing.

[0043] Step 3: Different ligand-coordinated Pt precursors, such as acetylacetones, halogens, amines, and nitro groups, are used. Synthesis conditions, including reaction temperature, reducing agent, and precursor dropping rate, are controlled to ensure that homogeneous nucleation does not occur while simultaneously allowing Ni or Co atoms to replace Pt ions in the precursor, thus achieving in-situ reduction of Pt nanoparticles. Furthermore, by controlling the reaction time and the extent of the substitution reaction, 1-4 layers of carbide structure are retained between the Pt particles and the carbon support, laying the foundation for the next step of constructing the interaction between the carbide and the carbon support.

[0044] Step 4: By controlling the temperature and atmosphere during the post-processing, the segregation rate and degree of carbon atoms in the carbide structure are regulated, and the precipitated carbon atoms and the carrier carbon atoms are integrated into a locally ordered structure, thereby enhancing the degree of interaction between them. This part can be combined with the second step and carried out before the in-situ growth process, depending on the properties of the carbide.

[0045] Example 1

[0046] This embodiment provides a method for preparing a fuel cell catalyst, specifically as follows:

[0047] S1. Dissolve 15.7 mg of nickel acetylacetone in a mixed solution of 9 mL oleylamine and 1 mL oleic acid, and sonicate to obtain a homogeneous solution. Then, transfer the solution to a 20 mL polytetrafluoroethylene liner, add 800 μL of formaldehyde solution, and stir at room temperature for 15 minutes. Remove the magnet and transfer the liner to a stainless steel outer liner, tighten it, and place it in an oven equipped with a programmable temperature control device. Within approximately 70 minutes, the oven temperature is raised from room temperature to 170°C and maintained at that temperature for 12 hours. Then, allow it to cool naturally to room temperature to obtain nickel carbide (Ni3C), in which carbon atoms occupy octahedral pores, and the atomic ratio of carbon to Ni is 1:3. Precipitate with anhydrous ethanol and centrifuge (10000 rpm, 5 minutes) to obtain a black solid. Then, wash and centrifuge with a 1:1 solution of anhydrous ethanol and n-hexane, repeating the process three times. Finally, vacuum dry to obtain the solid.

[0048] S2. A certain amount of carrier carbon is dispersed in a certain volume of n-butylamine at a concentration of 1 mg / mL. The mixture is sonicated in an ice bath for one hour to obtain a uniformly dispersed suspension for later use. The solid obtained in step S1 is sonicated and dispersed in n-butylamine (concentration of 1 mg / mL). The resulting solution is then added to the carbon n-butylamine suspension, wherein the Ni3C loading is 30 wt%. The mixture is sonicated in an ice bath for one hour, and then the solid is collected by centrifugation (11000 rpm, 8 minutes). The solid is washed five times with a 1:1 solution of n-hexane and anhydrous ethanol, and then washed three times with pure ethanol. The centrifuged solid is then dried in a vacuum drying oven.

[0049] S3. Place the solid obtained in step S2 and 9 mL of oleylamine in a 50 mL three-necked flask, sonicate to disperse, and raise the temperature to 120 °C. Add 10 mL of a 5 mM platinum acetylacetonate oleylamine solution dropwise using a syringe pump, ensuring the molar ratio of Ni to Pt is controlled at 1:0.85. After the addition is complete, keep warm for 1 h, then allow to cool naturally to room temperature. Precipitate with anhydrous ethanol and centrifuge (10000 rpm, 5 min) to obtain a black solid. Wash with a 1:1 solution of anhydrous ethanol and n-hexane, centrifuge, and repeat three times. Vacuum dry to obtain the solid.

[0050] S4. The solid obtained in step S3 is carbon-treated at 350°C for 12 hours under a 5% H2 + 95% N2 atmosphere to obtain the final solid catalyst.

[0051] like Figure 2 The figure shows the physical property characterization diagram of the carbide prepared in this embodiment. As can be seen from the figure, the transition metal carbide in this embodiment forms the basis of a stable "bridge" structure between Pt nanoparticles and carbon support in the fuel cell catalyst layer.

[0052] Based on the difference in standard reduction electrode potential between transition metals and Pt ions, this invention modulates the heterogeneous nucleation and growth process of Pt nanoparticles, growing Pt particles in situ on the surface of transition metal carbides. Simultaneously, one to several layers of carbide are retained between the carbon support and the Pt particles to enhance the interaction between them, thereby improving the stability of small-sized Pt particles on the carbon support. Figure 3 The image shown is a TEM image of the Pt / C catalyst prepared in this example.

[0053] like Figure 4 The figure shows the performance characterization of a single cell of the Pt / C catalyst prepared in Example 1 of this invention and a single cell of the commercial Pt / C catalyst in Comparative Example 1. The figure includes polarization curves, electrochemical active area (ECSA) retention rate, and mass activity (MA) retention rate before and after durability testing (30,000 cycles of 0.6-0.95V square wave). As can be seen from the figure, compared with the commercial catalyst, the improved catalyst of this invention, after low potential durability testing, has a voltage decay of only 20%-30% of that of the commercial catalyst in the full current density range, and the retention rates of electrochemical active area and mass activity are higher than those of the commercial catalyst.

[0054] Example 2

[0055] This embodiment provides a method for preparing a fuel cell catalyst, specifically as follows:

[0056] S1. Dissolve 1 mmol of nickel acetate tetrahydrate in a mixed solution of 3 mmol of oleylamine and 6 mL of octadecene, and sonicate to obtain a homogeneous solution. Then, add 1 mmol of trioctylphosphine to the solution. Within approximately 70 minutes, raise the oil bath temperature from room temperature to 130°C and hold for 1 hour. Then, rapidly raise the temperature to 240°C and hold for 1 hour, followed by natural cooling to room temperature. This yields Ni3C, in which carbon atoms occupy octahedral pores, with a carbon to Ni atomic ratio of 1:3. Precipitate with anhydrous ethanol and centrifuge (10000 rpm, 5 minutes) to obtain a black solid. Wash with a 1:1 solution of anhydrous ethanol and n-hexane, centrifuge, and repeat three times. Dry under vacuum to obtain the solid.

[0057] S2. A certain amount of carrier carbon is dispersed in a certain volume of n-butylamine at a concentration of 1 mg / mL. The mixture is sonicated in an ice bath for one hour to obtain a uniformly dispersed suspension for later use. The solid obtained in step S1 is sonicated and dispersed in n-butylamine (concentration of 1 mg / mL). The resulting solution is then added to the carbon n-butylamine suspension, wherein the Ni3C loading is 30 wt%. The mixture is sonicated in an ice bath for one hour, and then the solid is collected by centrifugation (11000 rpm, 8 minutes). The solid is washed five times with a 1:1 solution of n-hexane and anhydrous ethanol, and then washed three times with pure ethanol. The centrifuged solid is then dried in a vacuum drying oven.

[0058] S3. Place the solid obtained in step S2 and 9 mL of oleylamine in a 50 mL three-necked flask, sonicate to disperse, and raise the temperature to 120 °C. Add 10 mL of 5 mM oleylamine solution (5 mM platinum acetylacetonate) dropwise using a syringe pump, ensuring the molar ratio of Ni to Pt is controlled at 1:0.85. After the addition is complete, keep warm for 1 h, then allow to cool naturally to room temperature. Precipitate with anhydrous ethanol and centrifuge (10000 rpm, 5 min) to obtain a black solid. Wash with a 1:1 solution of anhydrous ethanol and n-hexane, centrifuge, and repeat three times. Vacuum dry to obtain the solid.

[0059] S4. The solid obtained in step S3 is treated at 350°C for 12 hours under a 5% H2 + 95% N2 atmosphere to obtain the final solid catalyst.

[0060] Example 3

[0061] This embodiment provides a method for preparing a fuel cell catalyst. Unlike Embodiment 1, in this embodiment, the amount of carbon atoms inserted (molar ratio) is 50% during the construction of the transition metal carbide.

[0062] Example 4

[0063] This embodiment provides a method for preparing a fuel cell catalyst. Unlike Embodiment 1, in this embodiment, the amount of carbon atoms inserted (molar ratio) is 100% during the construction of the transition metal carbide.

[0064] Example 5

[0065] This embodiment provides a method for preparing a fuel cell catalyst. Unlike Embodiment 1, in this embodiment, the temperature during the in-situ reduction of noble metal nanoparticles is controlled at 135°C.

[0066] Example 6

[0067] This embodiment provides a method for preparing a fuel cell catalyst. Unlike Embodiment 1, in this embodiment, the temperature during the in-situ reduction of noble metal nanoparticles is controlled at 150°C.

[0068] Example 7

[0069] This embodiment provides a method for preparing a fuel cell catalyst. Unlike Embodiment 1, in this embodiment, when noble metal nanoparticles are reduced in situ, the molar ratio of transition metal to noble metal element is controlled at 1:0.8.

[0070] Example 8

[0071] This embodiment provides a method for preparing a fuel cell catalyst. Unlike Embodiment 1, in this embodiment, when the noble metal nanoparticles are reduced in situ, the molar ratio of transition metal to noble metal element is controlled at 1:0.95.

[0072] Example 9

[0073] This embodiment provides a method for preparing a fuel cell catalyst. Unlike Embodiment 1, in this embodiment, a heat treatment method is used to establish a direct local bond relationship between the metal carbide structure and the carbon support, and the temperature is controlled at 300°C.

[0074] Example 10

[0075] This embodiment provides a method for preparing a fuel cell catalyst. Unlike Embodiment 1, in this embodiment, a heat treatment method is used to establish a direct local bond relationship between the metal carbide structure and the carbon support, and the temperature is controlled at 500°C.

[0076] Comparative Example 1

[0077] This comparative example provides a commercially available Pt / C catalyst from Tanaka Precious Metals.

[0078] It was verified that the Pt / C catalysts prepared in Comparative Examples 2-10 ( Figure 5 ) compared to the commercial Pt / C catalyst in Comparative Example 1 ( Figure 4 The results include the retention rates of electrochemical active area (ECSA) and mass activity (MA) before and after durability testing (30,000 cycles of 0.6-0.95V square wave). Compared with commercial catalysts, the improved catalyst of this invention has higher retention rates of both electrochemical active area and mass activity before and after low potential durability testing.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for improving the interaction between noble metal nanoparticles and carbon supports, characterized in that, Includes the following steps: S1. Dissolve 15.7 mg of nickel acetylacetone in a mixed solution of 9 mL oleylamine and 1 mL oleic acid, and sonicate to obtain a homogeneous solution. Then, transfer the solution to a 20 mL polytetrafluoroethylene liner, add 800 µL of formaldehyde solution, and stir at room temperature for 15 minutes. Remove the magnet and transfer the liner to a stainless steel liner, tighten it, and place it in an oven equipped with a programmable temperature control device. Raise the oven temperature from room temperature to 170 °C within 70 minutes and maintain the temperature for 12 hours. Then, allow it to cool naturally to room temperature to obtain nickel carbide, in which carbon atoms occupy octahedral pores and the atomic ratio of carbon to Ni is 1:

3. Then, precipitate it with anhydrous ethanol and centrifuge at 10,000 rpm for 5 minutes to obtain a black solid. Then, wash and centrifuge with a 1:1 solution of anhydrous ethanol and n-hexane, repeat three times, and vacuum dry to obtain a solid. S2. Take a certain amount of carrier carbon and disperse it in a certain volume of n-butylamine at a concentration of 1 mg / mL. Sonicate it in an ice bath for one hour to obtain a uniformly dispersed suspension for later use. Disperse the solid obtained in step S1 with n-butylamine using ultrasound. Then add the resulting solution to the carbon n-butylamine suspension, where the Ni3C loading is 30 wt%. Sonicate it in an ice bath for one hour. Then collect the solid by centrifugation at 11000 rpm for 8 minutes. Wash it 5 times with a 1:1 solution of n-hexane and anhydrous ethanol, and then wash it 3 times with pure ethanol. Dry the solid obtained by centrifugation in a vacuum drying oven. S3. Place the solid obtained in step S2 and 9 mL of oleylamine in a 50 mL three-necked flask, disperse by ultrasonication, and raise the temperature to 120℃. Add 10 mL of 5 mM oleylamine solution of platinum acetylacetonate dropwise using a syringe pump, ensuring that the molar ratio of Ni to Pt is controlled at 1:0.

85. After the addition is complete, keep warm for 1 h, and then let it cool naturally to room temperature. Then precipitate with anhydrous ethanol and centrifuge at 10000 rpm for 5 minutes to obtain a black solid. Wash with a 1:1 solution of anhydrous ethanol and n-hexane, centrifuge, and repeat three times. Vacuum dry to obtain the solid. S4. The solid obtained in step S3 is treated at 350°C for 12 hours under a 5% H2 + 95% N2 atmosphere to obtain the final solid catalyst.

2. A fuel cell catalyst, characterized in that, In the preparation of fuel cell catalysts, the method described in claim 1 is used to enhance the interaction between noble metal nanoparticles and carbon supports.

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