Gold-silver composite carbon supported catalyst based on oleylamine ligand and preparation method and application thereof

Abstract

The application discloses a kind of gold-silver composite carbon-supported catalysts based on oleylamine ligand and its preparation method and application, belong to the technical field of electrocatalytic carbon dioxide reduction, the gold-silver composite carbon-supported catalyst is by in-situ ligand control obtained dispersion type Au / C catalyst and hydrophobic type Ag nanoparticles mixed grinding obtained composite system.The catalyst surface of the application is modified with long-chain oleylamine Ag nanoparticles (20-60nm) uniformly distributed on Au / C (Au particle size <5nm).The hydrophobic Ag particles establish a hydrophobic layer inside the catalytic layer, and leave CO2 gas transmission channels, not easy to store liquid water, avoid water film completely covering catalyst layer to cause activity decline and voltage rapid growth.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic carbon dioxide reduction technology, and in particular to a gold-silver composite carbon-supported catalyst based on oleylamine ligands, its preparation method, and its application. Background Technology

[0002] Electrochemical reduction of CO2 to CO is currently the most commercially promising technological route. In industrial applications, gas diffusion electrodes (GDEs) or membrane electrode assemblies (MEAs) are typically used to support high current densities (>300 mA / cm²). Au and Ag are the mainstream catalysts for this reaction, and to reduce costs and improve the utilization of precious metals, carbon-supported metal nanoparticles (Au / C or Ag / C) are the main morphology.

[0003] Despite their high reactivity, Au and Ag present the following serious problems in actual industrial electrolyzer operation: "Flooding" leads to short lifespan: Under high current density, a large amount of liquid water is rapidly generated on the cathode side (reaction-generated water and transmembrane transport water). Traditional Au / C catalysts are usually reduced with sodium citrate or sodium borohydride, which have strong hydrophilicity. Liquid water easily accumulates in the micropores of the catalyst layer, flooding the active sites, blocking the CO2 gas transport channels, leading to local CO2 deficiency, exacerbating the hydrogen evolution reaction (HER), and causing a sharp increase in cell pressure. It typically fails within 100 hours of operation.

[0004] The preparation of Au-Ag alloys is difficult and unstable: Existing techniques attempt to utilize the bimetallic synergistic effect by preparing Au-Ag alloys. However, alloying typically requires high-temperature annealing (>300℃), which inevitably leads to the sintering and growth of metal particles (particle size increases from less than 5 nm to greater than 10 nm), significantly reducing the electrochemically active surface area (ECSA). Furthermore, during electrolysis, Ag atoms on the alloy surface are prone to segregation or oxidative leaching, resulting in lattice structure destruction and an inability to maintain stable catalytic performance over the long term.

[0005] Traditional composite methods are ineffective: Simply mixing commercial Ag nanoparticles with Au / C fails because the commercial Ag nanoparticles have a large particle size (>300nm) and no specific functional modifications on their surface, making it impossible to construct a uniform hydrophobic / hydrophilic balance network at the microscale, thus reducing the electrolytic activity of Au / C.

[0006] In addition to the aforementioned issues of catalytic performance and stability, the existing preparation processes for carbon-supported metal catalysts also restrict their industrial application. For example, the traditional two-step method (as disclosed in patent CN202180092398.4) requires the synthesis of metal nanoparticles in the liquid phase, followed by separation, washing, and redispersing steps to load them onto a carbon support. This process is lengthy and cumbersome, and the separation and redispersing processes are prone to causing the loss of precious metals and the aggregation of nanoparticles, resulting in poor batch consistency, uneven distribution of active sites, and difficulty in scaling up the process, making it difficult to meet the needs of large-scale production.

[0007] Therefore, developing a catalyst and its preparation method that can significantly improve the long-term operational stability of carbon dioxide electrolysis, while also possessing good process controllability and suitability for large-scale production, is of significant practical importance. This invention aims to construct a composite catalytic system with high activity, strong resistance to flooding, and long lifespan by optimizing the synthesis strategy of gold nanoparticles and introducing functionalized silver components. Simultaneously, it simplifies the preparation process and improves product consistency and industrial scale-up potential. Summary of the Invention

[0008] The purpose of this invention is to address the technical deficiencies in the prior art by providing a gold-silver composite carbon-supported catalyst based on oleylamine ligands.

[0009] Another object of the present invention is to provide a method for preparing the above-mentioned gold-silver composite carbon-supported catalyst.

[0010] Another object of the present invention is to provide the application of the above-mentioned gold-silver composite carbon-supported catalyst in gas diffusion electrodes (GDE) or membrane electrode assemblies (MEA) at high current densities.

[0011] The technical solution adopted to achieve the purpose of this invention is: A gold-silver composite carbon-supported catalyst based on oleylamine ligand, wherein the gold-silver composite carbon-supported catalyst is a composite system obtained by mixing and grinding a dispersed Au / C catalyst regulated by oleylamine ligand and hydrophobic Ag nanoparticles.

[0012] Another aspect of the present invention includes a method for preparing the gold-silver composite carbon-supported catalyst based on oleylamine ligands, comprising the following steps: The size and distribution of gold nanoparticles were controlled by oleylamine ligands, and then loaded onto a carbon support by liquid phase colloidal method to obtain an Au / C catalyst. After mixing with oleylamine-coated hydrophobic Ag nanoparticles, the catalyst was ground to obtain a gold-silver composite carbon-supported catalyst.

[0013] In the above technical solution, the oleylamine is a long-chain oleylamine.

[0014] In the above technical solution, the preparation method specifically includes the following steps: Step 1: Dissolve chloroauric acid or its salts in a mixture of oleylamine and a nonpolar solvent to obtain an Au precursor solution, and then add a reducing agent solution to react and form gold colloid. Step 2: Disperse the carbon support in a polar solvent, add it to the gold colloid from Step 1, stir until homogeneous, and dry to obtain the Au / C catalyst. Step 3: Dissolve silver salt in a mixture of oleylamine and a nonpolar solvent to obtain an Ag precursor solution, then add a reducing agent solution to react and form silver colloid, dry to obtain Ag nanoparticles; Step 4: Mix and grind the Au / C catalyst obtained in Step 2 with the Ag nanoparticles obtained in Step 3, and dry them to obtain the gold-silver composite carbon-supported catalyst.

[0015] In the above technical solution, in step 1, the chloroauric acid is chloroauric acid tetrahydrate or chloroauric acid trihydrate, and the nonpolar solvent is n-hexane, cyclohexane, n-octane, 1-octadecene, or toluene.

[0016] In the above technical solution, in step 1, the Au precursor solution is stirred and dissolved at 30~70℃, and the concentration of the Au precursor solution is 10~50 mmol / L.

[0017] In the above technical solution, the concentration of the reducing agent solution is 50~200 mmol / L, the molar ratio of the reducing agent to Au in the Au precursor solution is 1.5:1~5:1, and the reaction time is 10~60 minutes.

[0018] In the above technical solution, in step 2, the carbon support is Vulcan XC-72R carbon black, KetjenBlack EC-300J carbon black, or Ketjen Black ECP-600JD carbon black.

[0019] In the above technical solution, in step 2, the polar solvent is ethanol or isopropanol.

[0020] In the above technical solution, in step 2, the mass ratio of the carbon support to the Au in the gold colloid is 2:1 to 4:1.

[0021] In the above technical solution, in step 2, the stirring time is 12-24 hours, and then after centrifugation, washing and vacuum drying, Au / C catalyst is obtained.

[0022] In the above technical solution, in steps 1 and 3, the reducing agent solution is obtained by dissolving the reducing agent in a mixture of oleylamine and a nonpolar solvent, and the reducing agent is tert-butylamine boron, dimethylamine borane, or morpholine borane.

[0023] In the above technical solution, in step 3, the concentration of the Ag precursor solution is 20~100 mmol / L.

[0024] In the above technical solution, in step 3, the molar ratio of the reducing agent to Ag in the Ag precursor solution is 1:1 to 3:1, the reaction temperature is 30 to 80°C, and the reaction time is 60 to 120 minutes.

[0025] In the above technical solution, in step 3, after the reaction is completed, a settling agent is added, followed by centrifugation, washing multiple times with a mixed solution of ethanol and n-hexane, and then vacuum drying. The resulting Ag nanoparticles have a particle size of 20~60nm. The settling agent is methanol, and the volume ratio of ethanol to n-hexane in the mixed solution of ethanol and n-hexane is 3:1~6:1.

[0026] In the above technical solution, in step 4, the mass ratio of Ag to Au is 1:10 to 1:1.

[0027] In the above technical solution, in step 4, the grinding is ball milling with a ball-to-material ratio of 5:1 to 15:1. The ball milling is performed intermittently at 200 to 500 rpm, first for 10 to 20 minutes, then for 5 to 10 minutes of cooling, and the cycle is repeated 2 to 5 times. During the grinding process, 50 to 200 µL of dispersant is added.

[0028] In the above technical solution, the drying temperature in step 4 is 30~40℃.

[0029] Another aspect of the invention includes the application of the gold-silver composite carbon-supported catalyst in a gas diffusion electrode (GDE) or membrane electrode assembly (MEA) at high current densities.

[0030] Compared with the prior art, the beneficial effects of the present invention are: 1. Construction of microscopic gas-liquid channels: The gold-silver composite carbon-supported catalyst of this invention is modified with long-chain oleylamine Ag nanoparticles (20-60 nm) uniformly distributed on Au / C (Au particle size <5 nm). The hydrophobic Ag nanoparticles establish a hydrophobic layer inside the catalyst layer and leave CO2 gas transport channels, making it difficult to store liquid water, thus avoiding the decrease in activity and rapid voltage increase caused by the complete coverage of the catalyst layer by a water film; 2. Avoid the drawbacks of sintering and alloying: By using physical composite instead of high-temperature alloying, the ultra-small particle size of Au (high activity) is preserved, the auxiliary catalytic function of Ag is introduced, and the loss of active area caused by high-temperature treatment is avoided. 3. Long lifespan: Under operating conditions of 500 mA / cm², the lifespan of the gold-silver composite carbon-supported catalyst of this invention is more than 4 times longer than that of pure Au / C catalyst and more than 3 times longer than that of traditional physical mixing. 4. Scalable: This invention is simple to operate and highly controllable, effectively avoiding the redundant steps in the traditional intermittent method, improving product consistency, and has the potential for large-scale industrial production; 5. Although it's a physical mixing process (ball milling), Au and Ag achieve close contact at the micron / nanoscale. The introduction of Ag creates a more continuous electronic pathway between Au and C, reducing the rate of contact resistance deterioration during operation. Ag itself is also a CO product-directing metal with a high hydrogen evolution overpotential. Compared to a pure carbon support (which may have defect sites for hydrogen evolution), Ag particles cover part of the carbon surface, reducing the risk of hydrogen evolution on the carbon support. During long-term electrolysis, the carbon support typically becomes hydrophilic due to carbonate crystallization, causing the electrolyte to fill the pores of the catalyst layer (flooding), blocking CO2 supply. The incorporated hydrophobic Ag particles construct a persistent gas diffusion channel within the catalyst layer. The electrolyte cannot wet the surface of these oleylamine-coated Ag particles, thus retaining some pores as gas-phase channels for CO2. CO2 can be continuously transported to nearby Au active sites, preventing voltage spikes due to mass transfer limits. Attached Figure Description

[0031] Figure 1 These are TEM images of the Au / C catalysts of Example 1 and Example 2 of the present invention, where a is Example 1 and b is Example 2.

[0032] Figure 2 This is a TEM image of the aqueous Au / C catalyst in Comparative Example 2.

[0033] Figure 3 This is a graph showing the performance data from the long-term stability (lifetime) test of electrocatalysis. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0035] Example 1 A method for preparing a gold-silver composite carbon-supported catalyst based on oleylamine ligands includes the following steps: Step 1 specifically includes the following steps: Step 1.1: Add a magnetic stir bar to a clean, dry 500 mL three-necked flask, add 3.00 g of chloroauric acid (HAuCl4·3H2O, about 7.6 mmol), then add a mixture of 200 mL of oleylamine and 200 mL of n-hexane. Heat the mixture to 40°C in an oil bath and stir at 500 rpm for about 30 minutes until the solid is completely dissolved, to obtain an Au precursor solution (the solution is bright yellow). Step 1.2: Add 10 mmol of tert-butylamine boron to a 50 mL beaker, then add 15 mL of oleylamine and 15 mL of n-hexane, and sonicate until completely dissolved to obtain a reducing agent solution.

[0036] Step 1.3: Keep the temperature of the three-necked flask from Step 1.1 at 40°C, and quickly inject the reducing agent solution into the Au precursor solution in the three-necked flask all at once. The solution color will quickly change from yellow to dark purple. Continue stirring and reacting for 30 minutes to obtain gold sol.

[0037] Step 2: Weigh 7.00 g of Vulcan XC-72R carbon black into a 500 mL beaker, add 150 mL of anhydrous ethanol, sonicate for 30 minutes to disperse it evenly, and then slowly pour it into the gold sol obtained in Step 1.3. Continue to stir vigorously at room temperature for 18 hours, let the mixture stand to settle, discard the supernatant, transfer the remaining slurry to a centrifuge tube, centrifuge at 8000 rpm for 10 minutes, and discard the supernatant; resuspend the precipitate with anhydrous ethanol and wash it 4 times, and finally place it in a vacuum oven and dry it at 30°C for 12 hours. Grind to obtain an Au / C catalyst (powder) with a mass fraction of 30% Au.

[0038] Step 3 specifically includes the following steps: Step 3.1: Add 0.90 g of silver nitrate (AgNO3, about 5.3 mmol) to a 250 mL three-necked flask, then add a mixture of 35 mL of oleylamine and 35 mL of n-hexane, and stir at 60 °C until dissolved to obtain the Ag precursor solution.

[0039] Step 3.2: Dissolve 8 mmol of tert-butylamine boron in a mixture of 35 mL of oleylamine and 35 mL of n-hexane to obtain a reducing agent solution.

[0040] Step 3.3: Add the reducing agent solution obtained in step 3.2 dropwise to the Ag precursor solution obtained in step 3.1 (dropwise addition time is about 10 minutes). After the addition is complete, maintain 60°C and continue the reaction for 90 minutes to obtain silver sol.

[0041] Step 3.4: Add 100 mL of methanol as a settling agent to the silver sol obtained in step 3.3 and allow it to stand to separate into layers. Collect the precipitate by centrifugation, wash the precipitate three times with a mixture of ethanol / n-hexane (volume ratio 3:1) (Note: do not overwash to prevent ligand detachment), and vacuum dry at 30 °C to obtain Ag nanoparticles coated with oleylamine with a particle size distribution of 20~60 nm (denoted as Ag NPs).

[0042] Step 4: In a glove box, mix 2.00 g of the Au / C catalyst (powder) from Step 2 and 0.18 g of Ag nanoparticles (by mass ratio, Ag:Au = 3:10) to obtain a mixed powder. Add the mixed powder to a 50 mL agate ball mill jar, then add 20 zirconia balls with a diameter of 5 mm, and dropwise add 100 µL of anhydrous isopropanol. Tightly close the jar lid, seal it with sealing film, place it in a planetary ball mill, set the speed to 300 rpm, run for 10 minutes, stop the mill and cool for 5 minutes, repeat the cycle 3 times. Take out the powder and vacuum dry it at 40 °C until the solvent evaporates to obtain the gold-silver composite carbon-supported catalyst.

[0043] Example 2 A method for preparing a gold-silver composite carbon-supported catalyst based on oleylamine ligands. The method in this embodiment differs from that in Example 1 only in that, in step 4, 2.00 g of the Au / C catalyst (powder) from step 2 and 0.06 g of Ag nanoparticles (by mass ratio, Ag:Au=1:10) are mixed to obtain a mixed powder. All other steps are the same.

[0044] Depend on Figure 1 It can be seen that the particle size of the Au / C catalysts in Examples 1 and 2 is well controlled within 1~5nm, and the synthesis consistency is high.

[0045] Comparative Example 1 (using commercially available large-size silver powder, without hydrophobic ligands) A method for preparing a gold-silver composite carbon-supported catalyst includes the following steps: Compared with the method of Example 1, steps 1-2 are the same in this comparative example. Step 3 uses commercially available silver powder (average particle size 300 nm, surface without oleoamine coating). In step 4, 2.00 g of Au / C catalyst (powder) from Example 1 and 0.18 g of commercial silver powder are mixed. The rest of the process is the same as in Example 1.

[0046] Comparative Example 2 (Conventional two-step aqueous Au / C catalyst + Ag nanoparticles from Example 1) A method for preparing a gold-silver composite carbon-supported catalyst includes the following steps: Step 1, Au / C preparation (traditional sodium borohydride reduction method): Chloroauric acid is dissolved in water, sodium citrate is added, and sodium borohydride aqueous solution is added dropwise for vigorous reduction to obtain gold sol. Vulcan XC-72R is added for stirring and loading, followed by filtration and washing. The Au / C particles prepared by this method are relatively large and unevenly distributed, with a hydrophilic surface. The specific steps include: Step 1.1: Dissolve 1.20 g of chloroauric acid and 0.5 g of sodium citrate (citrate ions can play an electrostatic stabilizing role to prevent explosive agglomeration of gold particles during subsequent reduction) in 200 mL of deionized water, stir and sonicate for 20-30 minutes until completely dissolved to obtain a gold precursor solution that has been dispersed. Transfer the gold precursor solution to a three-necked flask, add a magnetic stir bar, and start stirring.

[0047] Step 1.2: Dissolve 0.5g of sodium borohydride in 200 mL of ice-cold deionized water and place it in a low-temperature water bath (controlling the temperature at 10~15℃) to reduce the reaction rate and facilitate the formation of smaller particle sizes, thus obtaining a sodium borohydride solution.

[0048] Step 1.3: Under vigorous stirring, add sodium borohydride solution dropwise to the gold precursor solution and continue stirring for 20-40 min to ensure complete reduction and obtain gold nanoparticle solution.

[0049] Step 2: Add 1.40 g of Vulcan XC-72R carbon black to a mixed solution of 300 mL of water and isopropanol (water:isopropanol = 5:1 by volume), and sonicate for 30-60 minutes until a uniform black carbon slurry is formed with no obvious large particles settling to the bottom, thus obtaining a fully dispersed carbon slurry. Slowly add the carbon slurry to the gold nanoparticle solution and stir continuously for 6-8 hours to ensure complete loading. Collect the solid product by filtration and wash the filter cake / precipitate 3-5 times with deionized water. Finally, wash once with anhydrous ethanol, place at room temperature for more than 24 hours, dry, and grind to obtain the aqueous Au / C catalyst.

[0050] Step 3: The preparation method of Ag nanoparticles is the same as in Example 1.

[0051] Step 4: Mix 2.00g of the aqueous Au / C catalyst obtained in Step 2 with 0.18g of Ag nanoparticles to prepare the catalyst. The remaining process is the same as Step 4 of Example 1.

[0052] Depend on Figure 2 It can be seen that the aqueous Au / C catalyst in this comparative example has a relatively wide particle size distribution (3~10 nm), with a small number of Au nanoparticles agglomerated to a relatively large size, around 10 nm. Compared to the wider particle size distribution of the Au / C catalyst in Example 1, the particle size distribution of Example 1 is more consistent; and the smaller particle size Au / C catalyst has higher metal utilization, a higher proportion of low-coordination active sites, and is more suitable for low-loading, high-activity design, thus generally resulting in higher mass activity and higher Faraday efficiency in CO2 reduction.

[0053] Comparative Example 3 (pure Au / C catalyst, without Ag composite) A method for preparing a gold-carbon supported catalyst includes the following steps: ball milling the Au / C catalyst (powder) prepared in Example 1 using the method in step 4 of Example 1 to prepare the gold-carbon supported catalyst.

[0054] Application Example 1 The catalysts prepared in Examples 1, 2, and Comparative Examples 1-3 were subjected to electrocatalytic testing, and the results are as follows: Figure 3 As shown.

[0055] Test conditions: Electrolytic CO2 cells were assembled using Examples 1-2 and Comparative Examples 1-3 as cathode catalysts, and their performance was tested. Furthermore, IrO2 was used as the anode catalyst, with both the cathode and anode metal loadings at 0.5 mg / cm³. -2 Using anion exchange membrane as the electrolyte membrane, the effective area of ​​the assembled membrane electrode is 25 cm². 2 Voltage lifetime test of the electrolytic cell under 500 mA / cm² conditions.

[0056] Depend on Figure 3 It can be seen that the catalyst of Example 1 has a lifetime that is more than 4 times longer than the gold-carbon supported catalyst (pure Au / C) of Comparative Example 3, and more than 3 times longer than the conventional physical mixing (Comparative Example 2). Example 1 successfully constructed a stable gas-liquid-solid three-phase interface. The hydrophobic Ag nanoparticles effectively suppressed the excessive wetting of the gas diffusion layer and catalyst layer by the electrolyte, preventing the "flooding" phenomenon, thus breaking the bottleneck of short lifetime of conventional catalysts. At the same time, compared with the catalyst of Example 2, the catalyst of Example 1 has the longest lifetime when the mass ratio of Ag to Au is 3:10. This is because when the mass ratio of Ag to Au is 3:10, a more continuous electronic pathway can be formed between Au / C, reducing the rate of contact resistance deterioration during operation, realizing the reconstruction of the catalyst layer microstructure, effectively improving the stress transmission of particle-level coordination, and reducing the risk of crack propagation and local delamination. In contrast, the mass ratio of Ag to Au of 1:10 is only scattered doping, which is insufficient to prevent the accumulation of local instability at the electrode scale, and therefore has no significant effect on delaying voltage collapse and the lifetime improvement is not significant.

[0057] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A gold-silver composite carbon-supported catalyst based on oleylamine ligands, characterized in that, The gold-silver composite carbon-supported catalyst is a composite system obtained by mixing and grinding a dispersed Au / C catalyst regulated by oleylamine ligand with hydrophobic Ag nanoparticles coated with oleylamine, wherein the grinding is ball milling.

2. The method for preparing the gold-silver composite carbon-supported catalyst based on oleylamine ligands according to claim 1, characterized in that, Includes the following steps: The size and distribution of gold nanoparticles were controlled by oleylamine ligands, and then loaded onto a carbon support by liquid phase colloidal method to obtain an Au / C catalyst. After mixing with oleylamine-coated hydrophobic Ag nanoparticles, the catalyst was ground to obtain a gold-silver composite carbon-supported catalyst.

3. The preparation method according to claim 2, characterized in that, The preparation method specifically includes the following steps: Step 1: Dissolve chloroauric acid or its salts in a mixture of oleylamine and a nonpolar solvent to obtain an Au precursor solution, and then add a reducing agent solution to react and form a gold sol. Step 2: Disperse the carbon support in a polar solvent, add it to the gold sol from Step 1, stir until homogeneous, and dry to obtain the Au / C catalyst. Step 3: Dissolve silver salt in a mixture of oleylamine and a nonpolar solvent to obtain an Ag precursor solution, then add a reducing agent solution to react and form a silver sol, and dry to obtain Ag nanoparticles. Step 4: Mix and grind the Au / C catalyst obtained in Step 2 with the Ag nanoparticles obtained in Step 3, and dry them to obtain the gold-silver composite carbon-supported catalyst.

4. The preparation method according to claim 3, characterized in that, In step 1, the chloroauric acid is chloroauric acid tetrahydrate or chloroauric acid trihydrate, and the nonpolar solvent is n-hexane or toluene. The Au precursor solution is dissolved by stirring at 30-70°C, and the concentration of the solution is 10-50 mmol / L. The concentration of the reducing agent solution is 50~200 mmol / L, the molar ratio of the reducing agent to Au in the Au precursor solution is 1.5:1~5:1, and the reaction time is 10~60 minutes.

5. The preparation method according to claim 3, characterized in that, In step 2, the carbon support is Vulcan XC-72R carbon black, Ketjen Black EC-300J carbon black, or Ketjen Black ECP-600J carbon black; The polar solvent is ethanol or isopropanol; The mass ratio of the carbon support to Au in the gold sol is 2:1 to 4:1; The stirring time is 12-24 hours, and then the Au / C catalyst is obtained after centrifugation, washing and vacuum drying.

6. The preparation method according to claim 3, characterized in that, In steps 1 and 3, the reducing agent solution is obtained by dissolving the reducing agent in a mixture of oleylamine and a nonpolar solvent, and the reducing agent is tert-butylamine boron, dimethylamine borane, or morpholine borane.

7. The preparation method according to claim 3, characterized in that, In step 3, the concentration of the Ag precursor solution is 20~100 mmol / L; The molar ratio of the reducing agent to Ag in the Ag precursor solution is 1:1 to 3:1, the reaction temperature is 30 to 80°C, and the reaction time is 60 to 120 minutes. After the reaction was completed, a settling agent was added, followed by centrifugation, washing multiple times with a mixed solution of ethanol and n-hexane, and then vacuum drying. The resulting Ag nanoparticles had a particle size of 20-60 nm. The settling agent was methanol, and the volume ratio of ethanol to n-hexane in the mixed solution was 3:1 to 6:

1.

8. The preparation method according to claim 3, characterized in that, In step 4, the mass ratio of Ag to Au is 1:10 to 1:

1.

9. The preparation method according to claim 3, characterized in that, In step 4, the ball-to-material ratio is 5:1 to 15:1, and intermittent ball milling is performed at 200 to 500 rpm. First, the ball milling is performed for 10 to 20 minutes, then cooled for 5 to 10 minutes, and the cycle is repeated 2 to 5 times. During the grinding process, 50 to 200 µL of dispersant is added. The drying temperature is 30~40℃.

10. The application of the gold-silver composite carbon-supported catalyst as described in claim 1 in a gas diffusion electrode or membrane electrode assembly under high current density.

Images