N, S co-doped hollow carbon nanocages confined Fe, Co bimetallic sites for bifunctional oxygen electrocatalysis

Regulating pore architecture and electronic structure is of significance for improving oxygen electrocatalytic activity of M-N-C catalysts. Herein, N, S co-doped hollow carbon nanocages confined Fe, Co bimetallic sites (FeCo-NS-HNCs) are constructed through an efficient surface bridging strategy. The surface modifier of tri-thiocyanuric acid trisodium salt bridges Co doped ZIF-8 surface with Fe ions to promote the formation of Fe/Co-Nx sites. The synergistic coupling of metal sites and N, S co-doping manipulates the adsorption/desorption characteristics of M-Nx sites to optimize intrinsic activity. The Kirkendall effect constructs the hollow carbon nanocages, improving the accessibility of M- Nx sites. Benefiting from the ameliorated electronic structure and hollow porous architecture, FeCo-NS-HNCs displays excellent bifunctional oxygen electrocatalytic activity (& UDelta;E = 0.655 V). The liquid and flexible Zn-air batteries of FeCo-NS-HNCs offer prominent power density and cycling stability. This work provides estimable insights into the structure design and activity regulation of M-N-C catalysts for Zn-air battery.