Pt-based alloy nano-catalyst as well as preparation method and application thereof

Abstract

The invention discloses a Pt-based alloy nano-catalyst as well as a preparation method and application thereof, and belongs to the technical field of metal nano-catalysts. The preparation method of the Pt-based alloy nano-catalyst comprises the following steps: adding a carbon source into a reaction solvent, and uniformly dispersing to obtain a carbon dispersion liquid; uniformly dispersing the platinum source solution, the transition metal source solution and the trace lithium chloride solution in the carbon dispersion liquid, and freeze-drying to obtain a precursor material; the molar ratio of Pt to LiCl in the platinum source is 3: (0.3-1), and calcining the precursor material to obtain the Pt-based alloy nano-catalyst. By controlling the use amount of LiCl, on the premise that high-temperature short-time treatment is conducted and it is guaranteed that the metal particles do not migrate, agglomerate and grow on the surface of the carbon source, the order degree of the metal particles is improved at the same time, and optimal balance of the particle size and the order degree is achieved.

Description

Technical Field

[0001] This invention relates to the field of metal nanocatalyst technology, and more specifically to a Pt-based alloy nanocatalyst, its preparation method, and its application. Background Technology

[0002] High-loading Pt-based alloy nanocatalysts are key materials for fuel cells. Experimental results and theoretical calculations show that ordered Pt-based alloy nanocatalysts in high-loading configurations possess stronger lattice contraction capabilities and stronger orbital coupling effects, which together enhance the intrinsic activity and structural stability of the oxygen reduction reaction. However, the high energy barrier associated with the order transition requires high-temperature treatment (≥700℃) to promote atomic diffusion and rearrangement, which inevitably leads to severe sintering of nanoparticles. Therefore, balancing particle size and order is a key challenge to overcome in the efficient preparation of Pt-based alloys.

[0003] Current methods for addressing metal particle migration during heat treatment include template methods, doping methods, and defect engineering. However, most of these methods focus on synthesizing low metal loading (≤20wt%). Under high loading conditions, metal particles are more densely distributed and more prone to agglomeration. Summary of the Invention

[0004] To address the above problems, this invention provides a Pt-based alloy nanocatalyst, its preparation method, and its applications. This invention utilizes the strong polarization forces of the cations and anions generated by the high-temperature melting of trace amounts of LiCl to reduce the stability of the metal salt ionic bonds in the precursor, thereby promoting the formation of new bonds. Simultaneously, the formation of a liquid environment promotes the diffusion of transition metal atoms into the platinum lattice and facilitates atomic rearrangement on the alloy particle surface. Under high-temperature, short-time treatment, the metal particles are prevented from migrating, agglomerating, or growing on the carbon source surface, while simultaneously improving the orderliness of the metal particles. Therefore, developing mild and easily operable methods to lower the reaction energy barrier and accelerate the reaction process is an effective solution for the efficient and controllable preparation of high-load Pt-based alloy nanocatalysts via thermal synthesis.

[0005] The first objective of this invention is to provide a method for preparing Pt-based alloy nanocatalysts, comprising the following steps: The carbon source and the reaction solvent are mixed evenly to obtain a carbon dispersion.

[0006] Platinum source solution, transition metal source solution and LiCl solution are uniformly dispersed in carbon dispersion, and then the carbon source is freeze-dried to obtain a loose structure to obtain the precursor material; the molar ratio of Pt to LiCl in the platinum source is 3:0.3 to 1.

[0007] The precursor material is calcined. During the calcination process, the molten LiCl formed promotes the reduction of platinum source and metal source to form ordered alloy particles, thus obtaining Pt-based alloy nanocatalyst.

[0008] In the preparation process, by controlling the amount of LiCl in the range of Pt:LiCl=3:0.3~1, the reduction energy barrier of platinum ions and transition metal ions can be effectively reduced, and the alloying process is promoted, while avoiding the particle agglomeration caused by excessive LiCl. The amount of LiCl directly affects the formation degree of the liquid environment during calcination: when the amount is too low, the effect of promoting atomic diffusion is insufficient, and the order degree is limited; when the amount is too high, a large area of liquid molten salt is formed, which leads to metal particle migration and agglomeration, and the particle size increases significantly. Therefore, by optimizing the amount of LiCl, the particle size growth can be controlled while improving the order degree, achieving the best balance between the two.

[0009] In the preparation, the carbon source is first uniformly dispersed in the reaction solvent to prepare for uniform loading of metal ions. In order to ensure the uniform dispersion of the carbon source, the ice water bath ultrasonic treatment time is 2h, the stirring treatment temperature is room temperature, the stirring rate is 300r / min~400r / min, and the stirring time is 20h.

[0010] Then introduce platinum source and transition metal source and LiCl into the carbon dispersion liquid. In the preparation process, by introducing other transition metal sources, the amount of platinum source can be reduced, which can reduce the preparation cost to a certain extent, and a small amount of LiCl can promote the reduction of Pt ions and transition metal ions, promote alloying and ordering. In the present application, the molar ratio of Pt in the platinum source to LiCl is 3:0.3~1 when adding LiCl; higher than this ratio will form a large area of liquid molten salt during calcination, leading to catalyst particle agglomeration and growth. In order to uniformly disperse the platinum source, other transition metal sources and trace LiCl in the above carbon dispersion liquid, and considering that the content of platinum source is high, there may be uneven dispersion, which may cause particle agglomeration during subsequent heat treatment, therefore, the method of spray freeze drying is adopted to ensure the loose structure of the carbon source, so that the metal salt can be uniformly adsorbed on the carbon source, and the carbon source is also avoided from being hardened during subsequent high temperature calcination.

[0011] It should be noted that the spray freeze drying method is used in the present application during freeze drying, the flow rate of spraying is 40mL / min, the vacuum degree of the freeze dryer is about 0.5Pa, the freeze drying temperature is-15°C, and the freeze drying time is about 72h. Then, the temperature is raised to 60°C and kept for two hours, which aims to further remove the water solution that may be left in the precursor, and to prevent the sample from being soaked by the liquefied water vapor in the air due to low temperature sampling.

[0012] The precursor material is calcined, the strong polarization force of the anion and cation generated in the molten state of LiCl reduces the stability of the metal salt ion bond in the precursor, thereby promoting the formation of new bonds, and at the same time forming a liquid environment to promote the diffusion of transition metal atoms into the platinum lattice and promote the rearrangement of atoms on the surface of alloy particles. Under the premise of high temperature short time treatment and ensuring that the metal particles do not migrate and agglomerate on the surface of the carbon source, a high ordered Pt-based alloy nanocatalyst is obtained. The precursor material after freeze-drying is calcined at high temperature to reduce the platinum source and other transition metal sources adsorbed on the surface of the carbon source into metal alloy at high temperature, thereby realizing the loading of Pt-based particles on the carbon source and forming a high-loading Pt-based nanocatalyst.

[0013] In a preferred embodiment of the present application, the molar ratio of Pt in the platinum source to LiCl is 3:0.6.

[0014] In a preferred embodiment of the present application, in the calcination process, the calcination temperature is 650-800 DEG C, and the calcination time is 2-3 h.

[0015] In a preferred embodiment of the present application, the mass ratio of C in the carbon source to Pt in the platinum source is 1:1-1.5.

[0016] In a preferred embodiment of the present application, the molar ratio of Pt in the platinum source to the metal in the transition metal source is 3:1-1.5. In the present application, the platinum source solution, the transition metal source solution, a small amount of LiCl and the carbon dispersion liquid are mixed in a dosage ratio of 5.00 mL:3.23 mL:8.5 mg:150.00 mL, then vacuum infiltration is performed until no bubbles are generated. The purpose of the infiltration is to make the water enter the carbon carrier pore as much as possible to meet the requirement of uniform loading of the subsequent metal source. Then dispersion is performed by ultrasonic stirring, and the ultrasonic stirring is performed under ice water bath condition, the stirring temperature is room temperature, the stirring speed is 300-400 r / min, and the stirring time is 16 h.

[0017] During the experiment, when preparing the transition metal source solution, the pH of the transition metal source solution can be adjusted according to the properties of the transition metal source. Taking CoCl2 as an example, the pH is adjusted to 2.51, so that CoCl2 can be better dissolved.

[0018] In a preferred embodiment of the present application, the volume ratio of the platinum source solution to the reaction solvent is 1:30-40.

[0019] In a preferred embodiment of the present application, the atmosphere in the calcination process is a mixed atmosphere of 95 vol% argon and 5 vol% hydrogen. The hydrogen is used as a reducing agent, and considering that hydrogen still exists after the calcination is completed, the atmosphere needs to be purged after the calcination is completed to prevent the sample from self-igniting when sampling, and nitrogen is used for purging in the present application.

[0020] In a preferred embodiment of the present application, the carbon source is one or more of carbon black, carbon nanotubes, non-metallic doped carbon material and metal-non-metal co-doped carbon material; the present application considers the factors of conductivity, stability and specific surface area required by the catalyst in the field of fuel cells, and selects the above-mentioned carbon source for preparation, wherein the non-metallic doped carbon material is selected from any one of P-doped carbon material, S-doped carbon material, N-doped carbon material and O-doped carbon material; and the metal-non-metal co-doped carbon material is selected from Fe-N co-doped carbon material or Co-O co-doped carbon material.

[0021] The platinum source is one or more of platinum tetrachloride, potassium chloroplatinate, chloroplatinic acid, sodium hydroxyplatinic acid, ammonium chloroplatous acid and sodium hexachloroplatinate.

[0022] The transition metal source is one or more of a ruthenium salt, a palladium salt, a nickel salt, a cobalt salt, a zinc salt and an iron salt; wherein the ruthenium salt is one or more of hydrated ruthenium trichloride, ruthenium acetate, potassium chlororuthenate, chlorocarbonylruthenate; the palladium salt is one or more of dichlorotetraammine palladium, palladium acetate, potassium chloropalladate, palladium acetylacetonate; the nickel salt is one or more of nickel nitrate, nickel sulfate, nickel chloride; the cobalt salt is one or more of cobalt chloride, cobalt nitrate, cobalt sulfate; the zinc salt is one or more of zinc chloride, zinc nitrate, zinc sulfate; and the iron salt is one or more of iron chloride, iron sulfate, iron nitrate.

[0023] The reaction solvent is one or more of water, methanol, acetone, tetrahydrofuran, chloroform and isopropyl alcohol. The present application considers the factors of dispersibility, stability of the carbon source after functionalization and solubility of the subsequent transition metal source, and according to the selected carbon source and transition metal source, the corresponding suitable reaction solvent is selected

[0024] A second object of the present application is to provide a Pt-based alloy nanocatalyst prepared by the above preparation method. Due to the addition of lithium chloride, the Pt-based alloy nanocatalyst prepared by the present application avoids metal particle migration and agglomeration growth (the particle size of the Pt-based alloy nanocatalyst is 3.11 nm to 3.87 nm), and the order degree of the Pt-based alloy nanocatalyst is increased from 34.92% to 53.38%.

[0025] The third object of the present application is to provide the use of the above-mentioned Pt-based alloy nanocatalyst in the preparation of a cathode of a fuel cell. The fuel cell comprises an anode and a cathode, and the cathode is prepared by spraying the Pt-based alloy nanocatalyst of the present application onto a proton exchange membrane, and the anode can be selected according to experimental requirements.

[0026] Compared with the prior art, the present application has the following beneficial effects: 1. During the preparation process, the strong polarization force of the anion and cation generated by the melting of trace LiCl (molar ratio of Pt to LiCl is 3:0.3-1) at high temperature reduces the stability of the metal salt ion bond in the precursor, thereby significantly promoting the formation of new bonds. At the same time, the local liquid environment formed by the melting of LiCl effectively promotes the diffusion of transition metal atoms into the platinum lattice and the atomic rearrangement on the surface of the alloy particles. The addition of LiCl reduces the reaction energy barrier, so that alloying and ordering can be achieved under calcination treatment, effectively inhibiting the migration and agglomeration of metal particles, so that the loading of Pt can be as high as 50wt%, and the order degree can be as high as 53.38%.

[0027] 2. By accurately controlling the amount of LiCl, the present application successfully realizes the optimization balance between the increase of catalyst particle size and the improvement of order degree. When the amount of LiCl is too low (such as Comparative Example 1), the promoting effect is insufficient, and the order degree is low; when the amount is too high (such as Example 5), it will lead to particle agglomeration and significant increase in particle size. When the amount of Pt:LiCl is 3:0.6, the catalyst maintains a small particle size (3.58±0.02nm) while obtaining the highest order degree (53.38%), solving the technical problem that high-temperature heat treatment is difficult to balance high-loading catalyst agglomeration and low order degree.

[0028] 3. The trace amount of LiCl used in the present application does not need complex post-treatment to remove it, and it will partially volatilize during high-temperature treatment, and the amount finally remaining in the catalyst is very small, which will not hinder the electrochemical reaction active site.

[0029] 4. Based on the above mechanism and process optimization, the prepared high-loading Pt-based alloy nanocatalyst has shown much higher catalytic activity and stability than the comparative sample without LiCl addition in a hydrogen-oxygen fuel cell. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 X-ray diffraction patterns of the Pt-based alloy nanocatalysts of Comparative Example 1 and Examples 1-5.

[0031] Figure 2 Order degree and particle size diagrams of the Pt-based alloy nanocatalysts of Comparative Example 1 and Examples 1-5.

[0032] Figure 3 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 1, and b is a particle size image of the Pt-based alloy nanocatalyst of Example 1.

[0033] Figure 4 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 1, and b is a particle size image of the Pt-based alloy nanocatalyst of Example 1.

[0034] Figure 5 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 2, and b is a particle size image of the Pt-based alloy nanocatalyst of Example 2.

[0035] Figure 6 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 3, and b is a particle size image of the Pt-based alloy nanocatalyst of Example 3.

[0036] Figure 7 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 4, and b is a particle size image of the Pt-based alloy nanocatalyst of Example 4.

[0037] Figure 8 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 5, and b is a particle size image of the Pt-based alloy nanocatalyst of Example 5.

[0038] Figure 9 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 6.

[0039] Figure 10 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 7.

[0040] Figure 11 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 8.

[0041] Figure 12 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 9.

[0042] Figure 13 In the figure, a is a high-resolution transmission electron microscope image of the Pt-based alloy nanocatalyst of Example 10.

[0043] Figure 14 In the figure, a is a cyclic voltammogram of the Pt-based alloy nanocatalyst of Comparative Example 1 and Examples 1 to 5.

[0044] Figure 15 In the figure, a is a step voltammogram of the Pt-based alloy nanocatalyst of Comparative Example 1 and Examples 1 to 5.

[0045] Figure 16 A comparison chart of mass activity (MA) and specific surface area activity (SA) of the Pt-based alloy nanocatalyst of Comparative Example 1 and Examples 1-5.

[0046] Figure 17 A hydrogen-oxygen fuel cell polarization curve chart of the Pt-based alloy nanocatalyst of Comparative Example 1.

[0047] Figure 18 A hydrogen-oxygen fuel cell polarization curve chart of the Pt-based alloy nanocatalyst of Example 3.

[0048] Figure 19 A hydrogen-oxygen fuel cell polarization curve chart of the Pt-based alloy nanocatalyst of Example 6.

[0049] Figure 20 A hydrogen-oxygen fuel cell polarization curve chart of the Pt-based alloy nanocatalyst of Example 7.

[0050] Figure 21 A hydrogen-oxygen fuel cell polarization curve chart of the Pt-based alloy nanocatalyst of Example 8.

[0051] Figure 22 A hydrogen-oxygen fuel cell polarization curve chart of the Pt-based alloy nanocatalyst of Example 9.

[0052] Figure 23 A hydrogen-oxygen fuel cell polarization curve chart of the Pt-based alloy nanocatalyst of Example 10. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without any creative effort belong to the protection scope of the present application.

[0054] To explore the influence of the amount of LiCl on the ordering degree of Pt3Co intermetallic compound, a series of Pt3Co / C(Li x )-700℃-2h catalysts (atomic ratio Pt:Co:Li=3:1:x, x=0.0, 0.3, 0.5, 0.6, 0.7, 1.0) were prepared. In Comparative Example 1, x=0; in Example 1, x=0.3; in Example 2, x=0.5; in Example 3, x=0.6; in Example 4, x=0.7; and in Example 5, x=1.0. The essential difference lies in the different amounts of LiCl added. The specific preparation method is described below in the examples and comparative examples.

[0055] Comparative Example 1 This comparative example provides a Pt-based alloy nanocatalyst, and it is prepared by the following steps: 1) 188.3 mg of carbon black was placed in a beaker, 150 mL of deionized water was added, and it was ultrasonically treated for 2 hours in an ice water bath at 10°C. Subsequently, it was placed in a vacuum drying box and vacuum impregnated at room temperature until no bubbles were generated, and then it was stirred at a rotation speed of 350 rpm for 20 hours to obtain a carbon dispersion liquid.

[0056] 10 g of H2PtCl6was completely dissolved in a 100 mL volumetric flask to prepare a H2PtCl6solution with a concentration of 37.66 mg Pt / mL.

[0057] 3.246 g of anhydrous cobalt chloride was weighed out and added to a 250 mL volumetric flask together with 117 μL of HCl, and then diluted to volume to prepare a cobalt chloride solution with a pH value of 2.51 and a concentration of 0.1 M.

[0058] 2) 17.50 mL of water was added to a 50 mL sample bottle, followed by the addition of 5 mL of the H2PtCl6solution with a concentration of 37.66 mg Pt / mL and 3.23 mL of the cobalt chloride solution with a concentration of 0.1 M. It was mixed thoroughly and ultrasonically treated for 10 min to obtain a mixed solution.

[0059] 3) The mixed solution was added dropwise to the carbon dispersion liquid under stirring using a burette. After the dropwise addition was completed, it was ultrasonically treated again for 30 min and stirred at the same rotation speed for 16 h. After spray freeze-drying, a precursor material of a high-loading Pt-based nanocatalyst was obtained.

[0060] 4) The precursor material was heated to 700°C and held for 2 h under a mixed gas atmosphere of 95 vol% argon and 5 vol% hydrogen, and then naturally cooled to room temperature. Purging was performed for 1 h under a nitrogen atmosphere to obtain a Pt-based nanocatalyst, which is denoted as Pt3Co / C(Li 0.0 )-700°C-2h.

[0061] Example 1 This example provides a high-loading Pt-based alloy nanocatalyst, and it is prepared by the following steps: 1) 188.3 mg of carbon black was placed in a beaker, 150 mL of deionized water was added, and it was ultrasonically treated for 2 hours in an ice water bath at 10°C. Subsequently, it was placed in a vacuum drying box and vacuum impregnated at room temperature until no bubbles were generated, and then it was stirred at a rotation speed of 350 rpm for 20 hours to obtain a carbon dispersion liquid.

[0062] 10 g H2PtCl6was completely dissolved in a 100 mL volumetric flask to prepare a H2PtCl6solution with a concentration of 37.66 mg Pt / mL.

[0063] 3.246 g of anhydrous CoCl2was weighed and added to a 250 mL volumetric flask together with 117 μL of HCl to prepare a CoCl2solution with a pH of 2.51 and a concentration of 0.1 M.

[0064] 2) 17.50 mL of water was added to a 50 mL sample bottle, followed by 4.24 mg of LiCl. Then 5 mL of H2PtCl6solution with a concentration of 37.66 mg Pt / mL and 3.23 mL of CoCl2solution with a concentration of 0.1 M were added. After mixing and ultrasonic treatment for 10 min, a lithium-containing mixed solution was obtained.

[0065] 3) The lithium-containing mixed solution was added dropwise to the carbon dispersion under stirring using a burette. After the addition was completed, the solution was ultrasonically treated for 30 min and stirred at the same speed for 16 h. After spray freeze-drying, a precursor material of a high-loading Pt-based nanocatalyst was obtained.

[0066] 4) The precursor material was heated to 700°C for 2 h under an atmosphere of a mixture of 95 vol% argon and 5 vol% hydrogen, and then naturally cooled to room temperature. After purging for 1 h under a nitrogen atmosphere, a Pt-based nanocatalyst was obtained, which was recorded as Pt3Co / C(Li 0.3 )-700°C-2h.

[0067] Example 2 This example provides a high-loading Pt-based alloy nanocatalyst, which is prepared by the following steps: 1) 188.3 mg of carbon black was placed in a beaker, 150.00 mL of deionized water was added, and ultrasonic treatment was performed for 2 hours in a 10°C ice water bath. Then, it was placed in a vacuum drying box and impregnated under vacuum at room temperature until no bubbles were generated. Then, it was stirred at a speed of 350 rpm for 20 hours to obtain a carbon dispersion.

[0068] 10 g H2PtCl6was completely dissolved in a 100 mL volumetric flask to prepare a H2PtCl6solution with a concentration of 37.66 mg Pt / mL.

[0069] 3.246 g of anhydrous CoCl2was weighed and added to a 250.00 mL volumetric flask together with 117 μL of HCl to prepare a CoCl2solution with a pH of 2.51 and a concentration of 0.1 M.

[0070] 2) Add 17.50 mL of water to a 50.00 mL sample vial, then add 7.1 mg of LiCl. Subsequently, add 5.00 mL of a solution with a concentration of 37.66 mg. Pt A lithium-containing mixed solution was obtained by mixing 3.23 mL of H₂PtCl₆ solution (1 mL) and 3.23 mL of 0.1 M CoCl₂ solution, followed by sonication for 10 min.

[0071] 3) The above lithium-containing mixed solution was added dropwise to the stirred carbon dispersion using a burette. After the addition was complete, the mixture was sonicated again for 30 min and stirred at the same speed for 16 h. After spray freeze-drying, a precursor material with high loading of Pt-based nanocatalyst was obtained.

[0072] 4) The above-mentioned precursor material was first heated to 700℃ and held for 2 hours in an atmosphere of 95 vol% argon and 5 vol% hydrogen, and then naturally cooled to room temperature; then purged under a nitrogen atmosphere for 1 hour to obtain the Pt-based nanocatalyst, denoted as Pt3Co / C(Li 0.5 -700°C for 2 hours.

[0073] Example 3 This embodiment provides a high-loading Pt-based alloy nanocatalyst, which is prepared through the following steps: 1) Place 188.3 mg of carbon black in a beaker, add 150.00 mL of deionized water, and sonicate in an ice-water bath at 10 °C for 2 hours. Then, place it in a vacuum drying oven and impregnate it under vacuum at room temperature until no bubbles are generated. Then, stir at 350 rpm for 20 hours to obtain a carbon dispersion.

[0074] 10.00 g of H₂PtCl₆ was completely dissolved in a 100.00 mL volumetric flask to prepare a solution with a concentration of 37.66 mg. Pt / mL of H2PtCl6 solution.

[0075] Weigh 3.246 g of anhydrous CoCl2 and add it together with 117 μL of HCl to a 250.00 mL volumetric flask to make up to volume, thus preparing a CoCl2 solution with a pH of 2.51 and a concentration of 0.1 M.

[0076] 2) Add 17.50 mL of water to a 50.00 mL sample vial, then add 8.5 mg of LiCl. Following this, add 5.00 mL of a solution with a concentration of 37.66 mg. Pt A lithium-containing mixed solution was obtained by mixing 3.23 mL of H₂PtCl₆ solution (1 mL) and 3.23 mL of 0.1 M CoCl₂ solution, followed by sonication for 10 min.

[0077] 3) The lithium-containing mixed solution is added dropwise into the carbon dispersion solution under stirring using a burette. After the addition is completed, the solution is ultrasonically treated for 30 min and stirred for 16 h at the same speed. The precursor material of the high-loading Pt-based nanocatalyst is obtained after spray freeze-drying.

[0078] 4) The precursor material is heated to 700°C and held for 2 h in an atmosphere of a mixture of 95 vol% argon and 5 vol% hydrogen, and then naturally cooled to room temperature. The Pt-based nanocatalyst is obtained after purging for 1 h in a nitrogen atmosphere, and is denoted as Pt3Co / C(Li 0.6 )-700°C-2h.

[0079] Example 4 The present example provides a high-loading Pt-based alloy nanocatalyst, and the nanocatalyst is prepared by the following steps: 1) 188.3 mg of carbon black is placed in a beaker, 150.00 mL of deionized water is added, and the solution is ultrasonically treated for 2 h in an ice water bath at 10°C. Subsequently, the solution is placed in a vacuum drying box and vacuum impregnated at room temperature until no bubbles are generated, and then stirred at a speed of 350 rpm for 20 h to obtain a carbon dispersion solution.

[0080] 10.00 g of H2PtCl6 is completely dissolved in a 100.00 mL volumetric flask to prepare a H2PtCl6 solution with a concentration of 37.66 mg Pt / mL.

[0081] 3.246 g of anhydrous CoCl2 is weighed and mixed with 117 μL of HCl, and then added to a 250.00 mL volumetric flask to prepare a CoCl2 solution with a pH value of 2.51 and a concentration of 0.1 M.

[0082] 2) 17.50 mL of water is added to a 50.00 mL sample bottle, and then 9.9 mg of LiCl is added. Subsequently, 5.00 mL of the H2PtCl6 solution with a concentration of 37.66 mg Pt / mL and 3.23 mL of the CoCl2 solution with a concentration of 0.1 M are added. The solution is mixed thoroughly and ultrasonically treated for 10 min to obtain a lithium-containing mixed solution.

[0083] 3) The lithium-containing mixed solution is added dropwise into the carbon dispersion solution under stirring using a burette. After the addition is completed, the solution is ultrasonically treated for 30 min and stirred for 16 h at the same speed. The precursor material of the high-loading Pt-based nanocatalyst is obtained after spray freeze-drying.

[0084] 4) The precursor material is heated to 700°C under an atmosphere of 95 vol% argon and 5 vol% hydrogen and held for 2 h, then naturally cooled to room temperature; then purged under a nitrogen atmosphere for 1 h to obtain a Pt-based nanocatalyst, denoted as Pt3Co / C(Li 0.7 -700°C-2h.

[0085] Example 5 The present example provides a high-loading Pt-based alloy nanocatalyst, and it is prepared by the following steps: 1) 188.3 mg of carbon black is placed in a beaker, 150.00 mL of deionized water is added, and ultrasonic treatment is performed for 2 hours in an ice water bath at 10°C. Subsequently, it is placed in a vacuum drying box, vacuumized at room temperature for impregnation until no bubbles are generated, then stirred at a rotation speed of 350 rpm for 20 hours to obtain a carbon dispersion liquid.

[0086] 10.00 g of H2PtCl6 is completely dissolved in a 100.00 mL volumetric flask to prepare a H2PtCl6 solution with a concentration of 37.66 mg Pt / mL.

[0087] 3.246 g of anhydrous CoCl2 is weighed, mixed with 117 μL of HCl, and added to a 250.00 mL volumetric flask to prepare a CoCl2 solution with a pH value of 2.51 and a concentration of 0.1 M.

[0088] 2) 17.50 mL of water is added to a 50.00 mL sample bottle, then 14.1 mg of LiCl is added. Subsequently, 5.00 mL of the H2PtCl6 solution with a concentration of 37.66 mg Pt / mL and 3.23 mL of the CoCl2 solution with a concentration of 0.1 M are added. Mix well and ultrasonic treatment is performed for 10 min to obtain a lithium-containing mixed solution.

[0089] 3) The lithium-containing mixed solution is added dropwise to the carbon dispersion liquid under stirring using a burette. After the dropwise addition is completed, ultrasonic treatment is performed again for 30 min, and stirring is performed at the same rotation speed for 16 h. After spray freeze-drying, a precursor material of a high-loading Pt-based nanocatalyst is obtained.

[0090] 4) The precursor material is heated to 700°C under an atmosphere of 95 vol% argon and 5 vol% hydrogen and held for 2 h, then naturally cooled to room temperature; then purged under a nitrogen atmosphere for 1 h to obtain a Pt-based nanocatalyst, denoted as Pt3Co / C(Li 1.0 -700°C-2h.

[0091] From the results of Comparative Example 1 and Examples 1-5, it can be seen that the amount of LiCl has a significant influence on the order degree and particle size of the Pt-based alloy nanocatalyst. As the amount of LiCl increases (x from 0 to 1.0), the order degree first increases and then decreases, reaching a maximum value (53.38%) at x = 0.6, while the particle size gradually increases with the value of x but remains in a small range (3.11 nm-3.87 nm). This shows that by controlling the amount of LiCl around Pt:LiCl = 3:0.6, the best balance of order degree and particle size can be achieved, which not only significantly improves the order degree of the catalyst, but also effectively inhibits the excessive growth of the particles, providing a key process parameter for the preparation of high-performance catalysts.

[0092] Example 6 This example provides a high-loading Pt-based alloy nanocatalyst, and it is prepared by the following steps: 1) Put 188.3 mg of carbon black into a beaker, add 150.00 mL of deionized water, and ultrasonically treat for 2 hours in an ice water bath at 10°C. Then, place it in a vacuum drying box and vacuumize at room temperature until no bubbles are generated, and then stir at a rotation speed of 350 rpm for 20 hours to obtain a carbon dispersion liquid.

[0093] Dissolve 10.00 g of H2PtCl6 in a 100.00 mL volumetric flask to prepare a H2PtCl6 solution with a concentration of 37.66 mg Pt / mL.

[0094] Weigh 5.186 g of anhydrous ruthenium chloride, and add 117 μL of HCl together into a 250.00 mL volumetric flask to prepare a ruthenium chloride solution with a pH value of 2.51 and a concentration of 0.1 M.

[0095] 2) Add 17.50 mL of water to a 50 mL sample bottle, and then add 8.5 mg of LiCl. Then add 5.00 mL of H2PtCl6 solution with a concentration of 37.66 mg Pt / mL and 3.23 mL of ruthenium chloride solution with a concentration of 0.1 M. Mix thoroughly and ultrasonically treat for 10 min to obtain a lithium-containing mixed solution.

[0096] 3) The lithium-containing mixed solution is added dropwise into the carbon dispersion liquid under stirring with a burette. After the addition is completed, ultrasonic treatment is performed again for 30 min, and stirring is performed at the same rotation speed for 16 h. After spray freeze-drying, the precursor material of the high-loading Pt-based nanocatalyst is obtained.

[0097] 4) The above precursor material was heated to 800℃ in an atmosphere of 95 vol% argon and 5 vol% hydrogen, and then calcined at 800℃ for 2 hours, followed by natural cooling to room temperature; then purged under a nitrogen atmosphere for 1 hour to obtain the Pt-based nanocatalyst, denoted as Pt3Ru / C(Li 0.6 -700°C for 2 hours.

[0098] Example 7 This embodiment provides a high-loading Pt-based alloy nanocatalyst, and its only difference from Example 1 is: This embodiment provides a high-loading Pt-based alloy nanocatalyst, which is prepared through the following steps: 1) Place 188.3 mg of carbon black in a beaker, add 150.00 mL of deionized water, and sonicate in an ice-water bath at 10 °C for 2 hours. Then, place it in a vacuum drying oven and impregnate it under vacuum at room temperature until no bubbles are generated. Then, stir at 350 rpm for 20 hours to obtain a carbon dispersion.

[0099] 10.00 g of H₂PtCl₆ was completely dissolved in a 100.00 mL volumetric flask to prepare a solution with a concentration of 37.66 mg. Pt / mL of H2PtCl6 solution.

[0100] Weigh 4.433 g of anhydrous palladium chloride and add it together with 117 μL of HCl to a 250.00 mL volumetric flask to make up to volume, thus preparing a palladium chloride solution with a pH of 2.51 and a concentration of 0.1 M.

[0101] 2) Add 17.50 mL of water to a 50 mL sample vial, then add 8.5 mg of LiCl. Following this, add 5 mL of a solution with a concentration of 37.66 mg / mL. Pt A lithium-containing mixed solution was obtained by mixing 3.23 mL of H₂PtCl₆ solution (1 mL) and 3.23 mL of 0.1 M palladium chloride solution, followed by sonication for 10 min.

[0102] 3) The above lithium-containing mixed solution was added dropwise to the stirred carbon dispersion using a burette. After the addition was complete, the mixture was sonicated again for 30 min and stirred at the same speed for 16 h. After spray freeze-drying, a precursor material with high loading of Pt-based nanocatalyst was obtained.

[0103] 4) The above precursor material was heated to 750℃ in an atmosphere of 95 vol% argon and 5 vol% hydrogen, and then calcined at 750℃ for 2 hours, followed by natural cooling to room temperature; then purged under a nitrogen atmosphere for 1 hour to obtain the Pt-based nanocatalyst, denoted as Pt3Pd / C(Li 0.6 -700°C for 2 hours.

[0104] Example 8 This example provides a high-loading Pt-based alloy nanocatalyst, and it is prepared by the following steps: 1) 188.3 mg of carbon black was placed in a beaker, 150.00 mL of deionized water was added, and it was ultrasonically treated for 2 hours in an ice water bath at 10°C. Subsequently, it was placed in a vacuum drying box and vacuumized at room temperature for impregnation until no bubbles were generated, and then it was stirred at a rotation speed of 350 rpm for 20 hours to obtain a carbon dispersion liquid.

[0105] 10.00 g of H2PtCl6was completely dissolved in a 100 mL volumetric flask to prepare a H2PtCl6solution with a concentration of 37.66 mg Pt / mL.

[0106] 3.240 g of anhydrous nickel chloride was weighed, mixed with 117 μL of HCl, and added to a 250.00 mL volumetric flask to prepare a nickel chloride solution with a pH value of 2.51 and a concentration of 0.1 M.

[0107] 2) 17.50 mL of water was added to a 50.00 mL sample bottle, followed by the addition of 8.5 mg of LiCl. Subsequently, 5.00 mL of the H2PtCl6solution with a concentration of 37.66 mg Pt / mL and 3.23 mL of the nickel chloride solution with a concentration of 0.1 M were added. It was mixed thoroughly and ultrasonically treated for 10 min to obtain a lithium-containing mixed solution.

[0108] 3) The lithium-containing mixed solution was added dropwise to the carbon dispersion liquid under stirring using a burette. After the dropwise addition was completed, it was ultrasonically treated again for 30 min and stirred at the same rotation speed for 16 h. After spray freeze-drying, a precursor material of a high-loading Pt-based nanocatalyst was obtained.

[0109] 4) The precursor material was heated to 700°C and held for 2 h under an atmosphere of a mixture of 95 vol% argon and 5 vol% hydrogen, and then naturally cooled to room temperature. Subsequently, it was purged for 1 h under a nitrogen atmosphere to obtain a Pt-based nanocatalyst, which is recorded as Pt3Ni / C(Li 0.6 )-700°C-2h.

[0110] Example 9 This example provides a high-loading Pt-based alloy nanocatalyst, and it is prepared by the following steps: 1) 188.3 mg of carbon black was placed in a beaker, 150.00 mL of deionized water was added, and it was ultrasonically treated for 2 hours in an ice water bath at 10°C. Subsequently, it was placed in a vacuum drying box and vacuumized at room temperature for impregnation until no bubbles were generated, and then it was stirred at a rotation speed of 350 rpm for 20 hours to obtain a carbon dispersion liquid.

[0111] Dissolve 10.00 g H2PtCl6in a 100.00 mL volumetric flask to prepare a H2PtCl6solution with a concentration of 37.66 mg Pt / mL.

[0112] Weigh 3.169 g of anhydrous ferrous chloride, and add 117 μL of HCl to a 250.00 mL volumetric flask to prepare a ferric chloride solution with a pH of 2.51 and a concentration of 0.1 M.

[0113] 2) Add 17.50 mL of water to a 50.00 mL sample bottle, then add 8.5 mg of LiCl. Subsequently, add 5.00 mL of the H2PtCl6solution with a concentration of 37.66 mg Pt / mL and 3.23 mL of the ferric chloride solution with a concentration of 0.1 M. Mix thoroughly and ultrasonically treat for 10 min to obtain a lithium-containing mixed solution.

[0114] 3) Add the lithium-containing mixed solution dropwise to the carbon dispersion under stirring using a burette. After the addition is complete, ultrasonically treat for 30 min again and stir at the same speed for 16 h. After spray freeze-drying, the precursor material of the high-loading Pt-based nanocatalyst is obtained.

[0115] 4) The precursor material is calcined at 650°C for 2 h under an atmosphere of a mixture of 95 vol% argon and 5 vol% hydrogen, and then naturally cooled to room temperature. The Pt-based nanocatalyst is obtained by purging under a nitrogen atmosphere for 1 h, and is recorded as Pt3Fe / C(Li 0.6 )-650°C-2h.

[0116] Example 10 This example provides a high-loading Pt-based alloy nanocatalyst, and is prepared by the following steps: 1) Place 188.3 mg of carbon black in a beaker, add 150.00 mL of deionized water, and ultrasonically treat for 2 hours in a 10°C ice water bath. Subsequently, place it in a vacuum drying box, and perform impregnation under vacuum at room temperature until no bubbles are generated. Then, stir at a speed of 350 rpm for 20 hours to obtain a carbon dispersion.

[0117] Dissolve 10.00 g H2PtCl6in a 100 mL volumetric flask to prepare a H2PtCl6solution with a concentration of 37.66 mg Pt / mL.

[0118] Weigh 3.408 g of anhydrous zinc chloride, and add 117 μL of HCl to a 250.00 mL volumetric flask to prepare a zinc chloride solution with a pH of 2.51 and a concentration of 0.1 M.

[0119] 2) Add 17.50 mL of water to a 50 mL sample vial, then add 8.5 mg of LiCl. Following this, add 5.00 mL of a solution with a concentration of 37.66 mg. Pt A lithium-containing mixed solution was obtained by mixing 3.23 mL of H₂PtCl₆ solution (1 mL) and 3.23 mL of 0.1 M zinc chloride solution, followed by ultrasonic treatment for 10 min.

[0120] 3) The above lithium-containing mixed solution was added dropwise to the stirred carbon dispersion using a burette. After the addition was complete, the mixture was sonicated again for 30 min and stirred at the same speed for 16 h. After spray freeze-drying, a precursor material with high loading of Pt-based nanocatalyst was obtained.

[0121] 4) The above-mentioned precursor material was first heated to 700°C in an atmosphere of 95 vol% argon and 5 vol% hydrogen, and then calcined at 700°C for 2 hours, followed by natural cooling to room temperature; then purged under a nitrogen atmosphere for 1 hour to obtain the Pt-based nanocatalyst, denoted as Pt3Zn / C(Li 0.6 -700°C for 2 hours.

[0122] Example 11 This embodiment provides a high-loading Pt-based alloy nanocatalyst, which is prepared through the following steps: 1) Place 125.5 mg of carbon black in a beaker, add 180 mL of deionized water, and sonicate in an ice-water bath at 10 °C for 2 hours. Then, place it in a vacuum drying oven and impregnate it under vacuum at room temperature until no bubbles are generated. Then, stir at 350 rpm for 20 hours to obtain a carbon dispersion.

[0123] 10g of H₂PtCl₆ was completely dissolved in a 100mL volumetric flask to prepare a solution with a concentration of 37.66mg. Pt / mL of H2PtCl6 solution.

[0124] Weigh 3.246 g of anhydrous CoCl2 and add it together with 117 μL of HCl to a 250 mL volumetric flask to make up to volume, thus preparing a CoCl2 solution with a pH of 2.51 and a concentration of 0.1 M.

[0125] 2) Add 17.50 mL of water to a 50 mL sample vial, then add 8.48 mg of LiCl. Following this, add 5 mL of a solution with a concentration of 37.66 mg / mL. Pt A lithium-containing mixed solution was obtained by mixing 4.2 mL of H₂PtCl₆ solution (1 mL) and 4.2 mL of 0.1 M CoCl₂ solution, followed by sonication for 10 min.

[0126] 3) The lithium-containing mixed solution is added dropwise into the carbon dispersion solution under stirring using a burette. After the dropwise addition is completed, the solution is ultrasonically treated for 30 min again and stirred at the same speed for 16 h. The precursor material of the high-loading Pt-based nanocatalyst is obtained after spray freeze-drying.

[0127] 4) The precursor material is heated to 800°C under an atmosphere of 95 vol% argon and 5 vol% hydrogen mixed gas and held for 2.5 h, and then naturally cooled to room temperature. The Pt-based nanocatalyst is obtained after purging under a nitrogen atmosphere for 1 h.

[0128] Example 12 The present example provides a high-loading Pt-based alloy nanocatalyst, which is prepared by the following steps: 1) 144.8 mg of carbon black is placed in a beaker, 200 mL of deionized water is added, and ultrasonic treatment is performed for 2 h in an ice water bath at 10°C. Subsequently, the solution is placed in a vacuum drying box, vacuum impregnated at room temperature until no air bubbles are generated, and then stirred at a speed of 350 rpm for 20 h to obtain a carbon dispersion solution.

[0129] 10 g of H2PtCl6 is completely dissolved in a 100 mL volumetric flask to prepare an H2PtCl6 solution with a concentration of 37.66 mg Pt / mL.

[0130] 3.246 g of anhydrous CoCl2 is weighed and added to a 250 mL volumetric flask together with 117 μL of HCl, and then diluted to the mark to prepare a CoCl2 solution with a pH value of 2.51 and a concentration of 0.1 M.

[0131] 2) 17.50 mL of water is added to a 50 mL sample bottle, followed by the addition of 8.48 mg of LiCl. Subsequently, 5 mL of the H2PtCl6 solution with a concentration of 37.66 mg Pt / mL and 4.8 mL of the CoCl2 solution with a concentration of 0.1 M are added. The solution is mixed thoroughly and ultrasonically treated for 10 min to obtain a lithium-containing mixed solution.

[0132] 3) The lithium-containing mixed solution is added dropwise into the carbon dispersion solution under stirring using a burette. After the dropwise addition is completed, the solution is ultrasonically treated for 30 min again and stirred at the same speed for 16 h. The precursor material of the high-loading Pt-based nanocatalyst is obtained after spray freeze-drying.

[0133] 4) The precursor material is heated to 750°C under an atmosphere of 95 vol% argon and 5 vol% hydrogen mixed gas and held for 3 h, and then naturally cooled to room temperature. The Pt-based nanocatalyst is obtained after purging under a nitrogen atmosphere for 1 h.

[0134] The performance is characterized below using Examples 1 to 10 and Comparative Example 1 as examples.

[0135] (a) Morphological test 1) X-ray diffraction tests of Comparative Example 1 and Examples 1 to 5 This invention takes the high-load Pt-based alloy nanocatalysts prepared in Comparative Example 1 and Examples 1 to 5 as examples, and performs X-ray diffraction tests on them respectively. The test results are as follows: Figure 1 As shown.

[0136] Depend on Figure 1 It can be seen that distinct characteristic peaks are observed at 23.06°, 32.84°, 40.53°, and 47.12°, corresponding to the (100), (110), (111), and (200) crystal planes of the Pt3Co standard crystal (PDF# 29-0499), respectively. The calculated Pt3Co / C(Li) x The degree of order (D) of the sample at -700℃ for 2 hours Figure 2 The curves exhibit a trend of volcano curves varying with the value of x, among which Pt3Co / C(Li) 0.6 The sample reached its peak value (53.38%) at x=0.6 after 2 hours at -700℃. This result indicates that the optimal LiCl addition amount can enhance the ordering of Pt3Co. Figure 1 In this context, intensity is denoted as Intensity. Figure 2 In this context, the degree of ordering is denoted as Degree of Ordering, and the diameter is denoted as Diameter.

[0137] 2) High-resolution transmission electron microscopy tests of Comparative Example 1 and Examples 1 to 10 The high-loading Pt-based alloy nanocatalyst prepared in this invention was subjected to high-resolution transmission electron microscopy (TEM) testing. The test results for Comparative Example 1 and Examples 1-5 are shown below. Figures 3-8 As shown, Figures 3-8 In this context, the frequency percentage is denoted as Frequency. Particle size gradually increases with the x-value (e.g., ...). Figure 2 The values ​​were 3.11 ± 0.03 (Pt3Co / C(Li)). 0.0 )-700°C-2h), 3.20±0.12 (Pt3Co / C(Li 0.3 )-700°C-2h), 3.31±0.05 (Pt3Co / C(Li 0.5 )-700°C-2h), 3.58±0.02 (Pt3Co / C(Li 0.6 )-700°C-2h), 3.63±0.04(Pt3Co / C(Li 0.7(-700°C-2h) and 3.87±0.16 nm (Pt3Co / C(Li) 1.0 -700°C for 2 hours.

[0138] The test results of Examples 6 to 10 are as follows: Figures 9-13 As shown, the prepared nanoparticles have a small particle size and are uniformly distributed on the carbon source.

[0139] (ii) Rotating Disk Electrode (RDE) Test Cyclic voltammetry curves of oxygen reduction reaction were obtained for Comparative Example 1 and Examples 1 to 5 respectively. Figure 14 ) and step-type cyclic voltammetry curve ( Figure 15 The tests were conducted, and the mass activity (MA) and specific surface area activity (SA) were calculated accordingly. (See attached data.) Figure 16 When x=0.6, MA and SA reach their maximum values, indicating that this is the optimal dosage. Figures 14-15 In this context, the potential relative to the reversible hydrogen electrode (RHE) is denoted as Potential / V vs. RHE, and the current density is denoted as Current Density.

[0140] (III) Performance Testing of Hydrogen-Oxygen Fuel Cells 1) Polarization curves of hydrogen-oxygen fuel cells in Comparative Example 1, Example 3, and Examples 6 to 10.

[0141] Taking the high-load Pt-based nanocatalysts prepared in Comparative Example 1 and Examples 3, 6-10 as examples, this invention uses the catalyst coating film (CCM) method to prepare nanocatalysts with a thickness of 5 cm. 2 Single-cell membrane electrodes (MEAs) with effective area. The anode catalyst used only commercial Pt / C, while the cathode catalyst employed the synthesized comparative example 1 and the high-load Pt-based nanocatalysts prepared in Examples 3, 6-10.

[0142] Commercial Pt / C slurry was prepared by ultrasonication: Pt / C powder (4.34 mg), deionized water (0.594 mL), isopropanol (0.756 mL) and 5% D521 Nafion ionomer solution (30.06 μL) were mixed and ultrasonicated for 40 minutes.

[0143] The high loading Pt-based nanocatalyst slurries prepared in Comparative Example 1, and Examples 3, 6-10 were prepared by sonicating a mixture of catalyst powder (4.00 mg), deionized water (1.174 mL), isopropyl alcohol (1.496 mL), and a 5% mass concentration of D521 Nafion ionomer solution (25.81 μί) for 150 minutes. The anode slurry was ultrasonically sprayed on a Gore membrane with a thickness of 18 μιη at 80 °C on a vacuum plate, and the cathode slurry was then sprayed on the other side of the membrane. To evaluate the performance of the fuel cell, the platinum loading of both the anode and cathode was maintained at 0.10 mg Pt ·cm -2 . The actual loading was confirmed by X-ray fluorescence analysis. The membrane electrode assembly was made by sandwiching the catalyst layer between two gas diffusion layers, and a piece of polytetrafluoroethylene gasket was placed on the outside of each gas diffusion layer. These gaskets ensured that the gas diffusion layers were compressed to about 70% of the original thickness. The MEA was then assembled into a single cell (containing a 5 cm 2 single-channel serpentine flow field, graphite plate, cell bolt tightened with a torque of 6 N-m). The assembled cell was connected to a fuel cell test bench (Scribner Associates Incorporated, 850e) for performance evaluation.

[0144] The polarization curve was recorded at 80 °C with the following parameters: the potential scan range was 1.0 to 0.2 V, the step value was 20 mV, and each step was held for 20 seconds; the anode was supplied with fully humidified H2(500 sccm); and the cathode was supplied with fully humidified O2(500 sccm). The anode and cathode pressures were both 250 kPa abs . The test results are shown in Figures 17-23 , Figures 17-23 where Cell Voltage is the cell voltage and Current Density is the current density. As can be seen from Figures 17-23 , the high loading Pt-based nanocatalysts prepared in Examples 3, 6-10 all exhibited excellent activity. Moreover, when the transition metal source was Co, the Pt-based nanocatalyst had even more excellent activity, because the ordered Pt3Co intermetallic compound exhibited enhanced lattice shrinkage and strong orbital coupling effects, which together improved its inherent oxygen reduction reaction activity and structural stability.

[0145] The present application provides a Pt-based alloy nanocatalyst, which is one of the efficient and stable solutions for the core bottleneck of the slow oxygen reduction reaction in fuel cells. For other battery systems, such reactions are not required, or the battery operating environment makes platinum ineffective or even harmful. Other mainstream battery technologies such as lithium-ion batteries, lead-acid batteries, and flow batteries have completely different working principles from fuel cells, so they do not need or are not suitable for using platinum-based catalysts. The reasons why other batteries do not need to use platinum-based catalysts are as follows.

[0146] (1) Lithium-ion batteries, the core reaction is intercalation / deintercalation.

[0147] Positive electrode: LiCoO2 ⇌ Li 1₋x CoO2 + xLi⁺ + xe⁻.

[0148] Negative electrode: C6 + xLi⁺ + xe⁻ ⇌ Li x C 6。

[0149] Lithium-ion batteries do not need catalysis at all: the charging and discharging of lithium is the intercalation and deintercalation process of lithium ions in the crystal structure of electrode materials, which is a bulk reaction, not a surface catalytic reaction. The reaction rate mainly depends on the diffusion ability and conductive network of the material itself, and has nothing to do with the surface catalytic activity. Using platinum not only has no benefit, but its huge cost and weight are fatal disadvantages.

[0150] (2) The core reaction of lead-acid batteries is dissolution-deposition.

[0151] Discharge process: Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2.

[0152] Different reaction mechanisms compared to fuel cells: the reaction of lead-acid batteries is the dissolution of Pb and PbO2 and the deposition of PbSO4 process, which does not require catalysis. And the cost is extremely mismatched: the core advantage of lead-acid batteries is extremely low cost. Using platinum catalysts that are thousands of times more expensive than lead is completely unfeasible and has no commercial application feasibility.

[0153] (3) Aqueous zinc batteries / alkaline batteries: taking alkaline zinc-manganese batteries as an example, the core reaction in alkaline medium is: 2MnO2 + Zn → Mn2O3 + ZnO.

[0154] Although platinum has ORR activity in alkaline environments, there are serious problems: under alkaline conditions, non-noble metals (such as manganese oxides, cobalt oxides) and even metal-free catalysts (such as doped carbon materials) also have good activity for ORR, with much lower cost than platinum. In addition, substances such as zinc and potassium commonly used in alkaline batteries can cause platinum catalysts to be poisoned, causing them to quickly lose activity.

[0155] (4) The core reaction of a vanadium redox flow battery is the change of ion valence.

[0156] Positive electrode: VO2+ 2+ + H2O ⇌ VO2+ + 2H+ + + 2H+ + + e - .

[0157] Negative electrode: V2+ 3+ + e- ⇌ V3+ 2+ .

[0158] It is different from the reaction type of fuel cells: the reaction of a flow battery is a simple one-electron transfer process, which is fast by itself and does not need expensive catalysts to speed it up. The electrode usually only needs to provide a large specific surface area and good electrical conductivity (such as carbon felt), rather than catalytic activity.

[0159] Although preferred embodiments of the application have been described, those skilled in the art will be able to make additional modifications and variations to the described embodiments without departing from the spirit and scope of the application. Accordingly, the appended claims are intended to encompass all modifications and variations of the preferred embodiments falling within the scope of the application.

[0160] Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A method for preparing a Pt-based alloy nanocatalyst, characterized in that, Includes the following steps: The carbon source and the reaction solvent are mixed evenly to obtain a carbon dispersion. Platinum source solution, transition metal source solution and trace lithium chloride solution were uniformly dispersed in carbon dispersion, and then the precursor material was obtained by freeze drying; the molar ratio of Pt to LiCl in the platinum source was 3:0.3-1. The precursor material is calcined. During the calcination process, the molten LiCl formed promotes the reduction of platinum source and metal source to form ordered alloy particles, thus obtaining Pt-based alloy nanocatalyst.

2. The method for preparing a Pt-based alloy nanocatalyst according to claim 1, characterized in that, The molar ratio of Pt to LiCl in the platinum source is 3:0.

6.

3. The method for preparing a Pt-based alloy nanocatalyst according to claim 1, characterized in that, During the calcination process, the calcination temperature is 650℃~800℃ and the calcination time is 2h~3h.

4. The method for preparing a Pt-based alloy nanocatalyst according to claim 1, characterized in that, The mass ratio of C in the carbon source to Pt in the platinum source is 1:1 to 1.

5.

5. The method for preparing a Pt-based alloy nanocatalyst according to claim 1, characterized in that, The molar ratio of Pt in the platinum source to the metal in the transition metal source is 3:1 to 1.

5.

6. The method for preparing a Pt-based alloy nanocatalyst according to claim 1, characterized in that, The volume ratio of platinum source solution to reaction solvent is 1:30 to 40.

7. The method for preparing a Pt-based alloy nanocatalyst according to claim 1, characterized in that, The atmosphere during the calcination process is a mixture of 95 vol% argon and 5 vol% hydrogen.

8. The method for preparing a Pt-based alloy nanocatalyst according to claim 1, characterized in that, The carbon source is one or more of carbon black, carbon nanotubes, non-metallic doped carbon materials, and metal-non-metal co-doped carbon materials; The platinum source is one or more of platinum tetrachloride, potassium chloroplatinate, chloroplatinic acid, sodium hydroxyplatinate, ammonium chloroplatinate, and sodium hexachloroplatinate; The transition metal source is one or more of the following: ruthenium salts, palladium salts, nickel salts, cobalt salts, zinc salts, and iron salts; The reaction solvent is one or more of water, methanol, acetone, tetrahydrofuran, chloroform, and isopropanol.

9. A Pt-based alloy nanocatalyst prepared by the preparation method according to claims 1-8, characterized in that, The particle size of the Pt-based alloy nanocatalyst is 3.11 nm to 3.87 nm.

10. The application of the Pt-based alloy nanocatalyst of claim 9 in the preparation of a cathode for a fuel cell.

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