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

Abstract

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