Constructing bifunctional Co/MoC@N-C catalyst via an in-situ encapsulation strategy for efficient oxygen electrocatalysis

The large-scale application of Zn-air battery requires the development of efficient, low-cost, and stable bifunctional electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Herein, an electrocatalyst of a Co/MoC-nanoparticles embedded N-doped carbon (Co/MoC@N-C) was prepared via the in-situ encapsulation of Co-2(CO)(8) and Mo(CO)(6) in ZIF-8 using ball-milling, followed by pyrolysis under an Ar atmosphere. When used as a bifunctional electrocatalyst, the as-prepared Co/MoC@N-C showed an ORR half-wave potential of 0.824 V in an alkaline medium and an overpotential of only 290 mV for the OER at 10 mA cm(-2), which was 70 mV lower than RuO2. The Co/MoC@N-C was also evaluated as a cathode in a solid-state Zn-air battery and delivered a higher peak discharge power density and better cycling stability (over 1600 min) than Pt/C-RuO2. Most importantly, our work provides a new strategy to prepare bifunctional catalysts and promotes their applications in the energy conversion field. (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.