Tuning interface mechanism of FeCo alloy embedded N,S-codoped carbon substrate for rechargeable Zn-air battery

Abstract

The interface mechanism between catalyst and carbon substrate has been the focus of research. In this paper, the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst (FeCo/S-NC) is obtained by a simple one-step pyrolysis strategy. The experimental results and density functional theory (DFT) calculation show that the formation of FeCo alloy is conducive to promoting electron transfer, and the introduction of S atom can enhance the interaction between FeCo alloy and carbon substrate, thus inhibiting the migration and agglomeration of particles on the surface of carbon material. The FeCo/S-NC catalysts show outstanding performance for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). FeCo/S-NC shows a high half-wave potential (E1/2 = 0.8823 V) for ORR and a low overpotential at 10 mA cm−2 (Ej=10 = 299 mV) for OER. In addition, compared with Pt/C+RuO2 assembled Zn-air battery (ZAB), the FeCo/S-NC assembled ZAB exhibits a larger power density (198.8 mW cm−2), a higher specific capacity (786.1 mA h gZn−1), and ultra-stable cycle performance. These results confirm that the optimized composition and the interfacial interaction between catalyst and carbon substrate synergistically enhance the electrochemical performance.