Integrating two different catalytic active sites into one composite is a useful 2-in-1 strategy for designing high-efficient bifunctional catalysts,which can easily tailor the activity of each reaction.Hence,we adopt the 2-in-1 strategy to design the metal oxyhydroxide supported on N-doped porous carbons(PA-CoFe@NPC)as the oxygen bifunctional catalyst,where NPC provides the activity for oxygen reduction reaction(ORR)while the metal oxyhydroxide is responsible for oxygen evolution reaction(OER).Results demonstrate that the PA-CoFe@NPC indeed exhibits both super ORR and OER activities.Impressively,using bifunctional PA-CoFe@NPC as the oxygen electrode,the resulting Zn-air battery exhibits outstanding charge and discharge performance with the peak power density of 156.3 mW cm^(-2),and also exhibits a long-term cycle stability with continuous cyclic charge and discharge of 170 hours that is obviously better than the 20%Pt/C+IrO_(2)based one.The 2-in-1 strategy in this work can be efficiently extended to design other bi-or multi-functional electrocatalysts.
Huibing LiuRixin XieZiqiang NiuQiaohuan JiaLiu YangShitao WangDapeng Cao
Currently,FeNi nanoalloys have received considerable attention for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)in rechargeable aqueous zinc(Zn)-air batteries(ZABs)because of their high content and good chemical stability.However,their poor electronic conductivity,small surface area,and sluggish activity seriously hinder their catalytic performance.Herein,S-modulated FeNi nanoalloys supported by hierarchically porous carbon(SFeNi/PC)are synthesized through the thermal treatment of metal-organic precursors for efficient bifunctional oxygen catalysis.S decoration endows S-FeNi/PC with a superior OER performance while maintaining an ORR performance that is comparable to that of Pt/C.Hence,S-FeNi/PC exhibits excellent bifunctional oxygen catalytic activity,outperforming the noble-metal-based composite catalysts of Pt/C and RuO_(2).Notably,the ZABs assembled with S-FeNi/PC exhibit high specific capacity(792 mA h g^(-1)),high peak power density(123.5 mW cm^(-2)),and remarkable durability for 700 charge/discharge cycles at 10 mA cm^(-2),which surpasses the performance of commercially available Pt/C-RuOand other catalysts in previously reported studies.This study will provide not only new bifunctional oxygen electrodes for efficient ZAB devices but also new insights into the design of FeNi-based materials for a wide range of catalytic applications.
