Preparation Of Carbon-Based Bimetallic Atomic-Level Dispersion Catalysts And Their Electrocatalytic Activity

With the increasing consumption of fossil fuels and environmental pollution problems,the search for sustainable and clean energy sources and related technologies has become an urgent task before mankind.At present,the practical application of fuel cells faces serious challenges such as high cost and poor stability of noble metal ORR catalysts.For this reason,it becomes crucial to explore low-cost and high-activity non-precious metal ORR catalysts.Single-atom catalysts,as the frontier of ORR catalyst research,have been widely reported for their maximum atom utilization efficiency.In contrast,compared with monoatomic catalysts,atomic-level dispersion catalysts with bimetallic active sites have greater advantages,and their interatomic synergy can effectively improve the catalytic activity and promote ORR at the fuel cell cathode.Therefore,conducting research on bimetallic atomic-level dispersion catalysts will provide more stable and efficient ORR catalysts for practical applications in fuel cells.In this paper,Fe Co bimetallic loaded electrocatalysts with different structures were prepared by secondary carbide metal loading method,vapor deposition method and template agent method,and a unique fluidized state high-temperature calcination method was designed to make the macroscopic preparation of catalysts possible.The research mainly includes:（1）A method for the preparation of highly active Fe Co bimetallic atomic level dispersion catalysts using ZIF-8/67 hybrid precursor structure and secondary carbonized metal loading method was developed to enhance the activity and stability of Fe Co-N-C-2 catalysts through bimetallic synergy,high active site density and good electrical conductivity.Its ORR half-wave potentials at 0.1 M HCl O₄and 0.1 M KOH were 0.806 V and 0.917 V,respectively,and it maintained 91.21%and 92.80%activity after 50,000 s constant potential test.In addition,its OER overpotential corresponding to 1M KOH electrolyte and 10 m A·cm^-2current density was 0.339 V,showing excellent ORR/OER dual-effect electrocatalytic activity and stability.Its peak power density in PEMFC and alkaline zinc-air cells can reach 746 m W·cm^-2and 164 m W·cm^-2,respectively,demonstrating excellent cell device performance.（2）The preparation of highly active Fe Co bimetallic atomic-level dispersion catalysts by using urea nitrogen supplementation,ammonium chloride to enhance catalyst carbon defects and vapor deposition metal loading method was investigated to enhance the activity and stability of Fe Co-N-C@U-AC catalysts through bimetallic synergy,high active site density and high catalytic active site accessibility.Its ORR half-wave potentials at 0.1 M HCl O₄and 0.1 M KOH were 0.820 V and 0.911 V,respectively,and the activity could still maintain the original 93.25%and98.38%after 50,000 s constant potential test,showing excellent electrocatalytic activity and stability.Its peak power density can reach 859m W·cm^-2and 162 m W·cm^-2in PEMFC and alkaline zinc-air batteries,respectively,showing excellent battery device performance.（3）A method was developed for the preparation of highly active bimetallic loaded electrocatalysts Fe Co-N-C-OAc by using a template agent to modulate the graded porous structure of the catalyst and designing and using a fluidized high-temperature calcination method to efficiently complete the scale up of the catalyst precursor.Its ORR half-wave potentials were 0.778 V and0.905 V at 0.1 M HCl O₄and 0.1 M KOH,respectively,and it maintained94.43%and 98.41%activity after 50,000 s constant potential test,showing good electrocatalytic activity and stability.Its peak power density can reach993 m W·cm^-2and 162 m W·cm^-2in PEMFC and alkaline zinc-air batteries,respectively,showing excellent battery device performance.This preparation process and the application of the related catalysts are important for promoting the practical industrial production of non-precious metal carbide electrocatalysts with fuel cell power stacks.