Interfacial Electron Redistribution of FeCo2S4/N-S-rGO Boosting Bifunctional Oxygen Electrocatalysis Performance

Abstract

Developing bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is essential for the development of zinc–air batteries (ZABs), but several challenges remain in terms of bifunctional activity. FeCo2S4/N-S-rGO was prepared by in situ homogeneous growth of bimetallic sulfide FeCo2S4 on N, S-doped reduced graphene oxide. FeCo2S4/N-S-rGO exhibits a half-wave potential of 0.89 V for ORR and an overpotential of 0.26 V at 10 mA cm−2 for OER, showing significantly bifunctional activity superior to Pt/C (0.85 V) and RuO2 (0.41 V). Moreover, the FeCo2S4/N-S-rGO assembled ZAB shows a superior specific capacity and a power density of 259.13 mW cm−2. It is demonstrated that the interfacial electron redistribution between FeCo2S4 nanoparticles and heteroatom-doped rGO matrix can efficiently improve the electrochemical performance of the catalyst. The results provide new insights into the preparation of high-capability composite catalysts combining transition metal sulfides with carbon materials for applications in ZABs.