Strong coupled spinel oxide with N-rGO for high-efficiency ORR/OER bifunctional electrocatalyst of Zn-air batteries

The high cost, scarcity, and poor stability of precious-metal-based catalysts have hindered their extensive application in energy conversion and storage. This stimulates the search for earth-abundant alternatives to replace noble metal electrocatalysts. Hence, in this study, we investigate a novel and low-cost bifunc-tional electrocatalyst consisting of ZnCoMnO4 anchored on nitrogen-doped graphene oxide (ZnCoMnO4/ N-rGO). Benefiting from the strong Co-N interaction in ZnCoMnO4 and the coupled conductive N-rGO, the catalysts exhibit high electrocatalytic activity. Moreover, density functional theory calculations support the dominant role of the strong Co-N electronic interaction, which leads to ZnCoMnO4/N-rGO having more favorable binding energies with O-2 and H2O, resulting in fast reaction kinetics. The obtained ZnCoMnO4/N-rGO electrocatalyst exhibits superb bifunctional activity, with a half-wave potential of 0.83 V for the oxygen reduction reaction and a low onset potential of 1.57 V for the oxygen evolution reaction in 0.1 M KOH solution. Furthermore, a Zn-air battery driven by the ZnCoMnO4/N-rGO catalyst shows remarkable discharge/charge performance, with a power density of 138.52 mW cm(-2) and long-term cycling stability for 48 h. This work provides a promising multifunctional electrocatalyst based on non-noble metals for the storage and conversion of renewable energy. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

This study presents a novel and low-cost bifunctional electrocatalyst based on non-noble metals, which exhibits high electrocatalytic activity and superior performance, with remarkable bifunctional activity and long-term stability in 0.1 M KOH solution.