Mn-Doped Co–N–C Dodecahedron as a Bifunctional\nElectrocatalyst for Highly Efficient Zn–Air Batteries

Abstract

The\nprogress of high-efficiency electrocatalysts toward the oxygen\nreduction reaction and oxygen evolution reaction (ORR and OER) is\ncentral to reproductive fuel cells and rechargeable metal–air\nbatteries. Transition-metal-based catalysts with superb activity and\nstability are highly considered as an alternative of the present noble-metal-based\nelectrocatalysts. Herein, we reported a simple construction of Mn-doped\nCo–N–C (Mn/Co–N–C) as an excellent bifunctional\nORR/OER electrocatalyst. It is found that the enhanced ORR/OER electrocatalytic\nactivity benefits by suitably doping Mn, which affects the electronic\nstructure of the Co species. The optimized Mn/Co–N–C\nexhibits excellent ORR/OER performance with a potential difference\nof 0.86 V, which outperforms a commercial Pt/C electrocatalyst (0.93\nV). Rechargeable liquid zinc–air batteries based on the Mn/Co–N–C\nbifunctional catalyst exhibit initial discharge and charge potentials\nat 1.20 and 2.02 V (5 mA cm^–2), along with an outstanding\nstability with negligible increase in polarization even after 250\nh. Furthermore, the all-solid-state zinc–air batteries fabricated\nwith the Mn/Co–N–C bifunctional catalyst also display\nan outstanding lifetime with 60 cycles (2 mA cm^–2) and steady charge/discharge potential even upon bending.