Preparation Of ZIF-Derived Carbon-Based Fe-Co Bimetallic Electrocatalyst And Its Performance Study For Zinc-Air Batteries

The rapid and continuing decline of natural fossil fuel resources,the environmental crisis,and the need for clean and sustainable energy sources are undoubtedly driving current research and development into energy assets such as hydrogen,fuel cells,and metallic air batteries.With Zn-air batteries（ZABs）being cost-effective and energy-dense,A promising energy storage device for renewable energy and electric transportation power sources.However,the slow dynamics of cathode materials,limited charge and discharge cycles,and low round-trip efficiency have long been obstacles to the large-scale application of ZABs in the market.In the past,materials containing Pt,Pd,Ru,Rh,or Ir as noble metals or as derivatives of their oxides have shown the best efficiency as electrocatalysts for the above-mentioned reactions.However,the high cost of such catalysts has hindered their industrial application.In addition,the stability of the catalyst family is relatively low,requiring frequent replacement and unable to catalyze both oxygen reduction reaction（ORR）and oxygen evolution reaction（OER）.For these reasons,there is a great demand for dual-function,cheap and stable electrocatalysts.Therefore,it is necessary to develop bifunctive catalysts that can catalyze rechargeable ZABs and are economically feasible and stable.In view of the above problems,non-noble metal bi-functional catalyst was designed and synthesized for Zn-air battery.The following two design schemes were made to explore:（1）Because of the practical applications for nonprecious-alloy catalysts in industrial production,Zn-air batteries must be urgently developed to design dual-function electrocatalysts with excellent performance,low price,and facile production steps.This study proposed a newly developed iron,cobalt,and zinc coordination zeolite imidazole skeleton（Fe Co-ZIF）,which does not require an additional carbon source and reduces environmental pollution.A flake fluffy structure was formed after pyrolysis enhanced metal particle dispersion.Compared with industrial Pt/C（0.837 V half-wave potential）and Ru O₂（overpotential）,novel Fe-Co-N-C-900 improved oxygen reduction（0.859 V half-wave potential）,and oxygen precipitation(343 m V overvoltage at 10 m A cm^-2)characteristics because the combination of Fe and Co favoured bifunctional properties.Liquid and solid ZABs are prepared using Fe-Co-N-C-900 as an air cathode.Experimental results showed that liquid ZABs present a higher peak power density(125 m W cm^-2)and are steadier during cycling than traditional Pt/C+Ru O₂catalysts.Liquid and flexible rechargeable ZABs attained the open-circuit voltages of 1.460 and 1.476 V,respectively.This simple synthesis strategy can provide a novel approach to preparing dual-function catalysts with energy storage and conversion applications.（2）In recent years,bifunctional electrocatalysts derived from zeolite imidazole framework（ZIF）as a carbon substrate have been a hot research topic.In addition,one-component catalyst cannot achieve the efficient catalysis of oxygen reduction reaction and oxygen evolution reaction.At the same time,this paper reports a bifunctional catalyst with a bimetallic three-dimensional porous structure using silicon spheres as a hard template and ZIF as a carbon substrate.The inherent porosity of pie-shaped ZIF,the use of silica templates to generate an ordered macroporous structure,and the synergy between metal activity sites,which together promote the mass transfer and electrocatalytic activity of the battery.The synthesized catalyst showed excellent electrocatalytic activity toward ORR and OER including a half-wave potential(E_1/2=0.80 V)which is 20 m V less than Pt/C,and its overpotential（0.321 V）and voltage gap（ΔE=0.751 V）surpasses commercial Pt/C+Ru O₂catalyst（0.368 V,ΔE=0.778 V）.Moreover,the rechargeable Zn-air battery assembled based on this catalyst exhibits excellent performance,including high power density(98.7 m W cm^-2)and battery charge/discharge cycle stability（220h）that exceeds that of commercial Pt/C+Ru O₂catalysts（160h）.Given its unique pore structure and good electrical conductivity,this derived material has scope for expansion in bifunctional catalysis and other energy technologies for rechargeable Zn-air batteries.Figure 38 table 10 reference 164...