In Situ Coupling of MnO and Co@N-Doped Graphite Carbon Derived from Prussian Blue Analogous Achieves High-Performance Reversible Oxygen Electrocatalysis for Zn-Air Batteries.

Abstract

Coupling dual active components into one integrated catalyst as well as understanding their electronic interaction behavior on reversible oxygen electrocatalysis is central to achieving high energy-conversion efficiency for Zn-air batteries (ZABs). Herein, we demonstrate an effective couple of MnO and Co nanocrystals embedded in N-doped graphite carbon to integrate a highly efficient bifunctional catalyst (denoted as MnO/Co@NGC) toward oxygen reduction and evolution reaction (ORR/OER). MnO/Co@NGC was first successfully prepared by the one-step pyrolysis of Mn3[Co(CN)6]2·9H2O@PVP (poly(vinyl pyrrolidone)), and X-ray absorption near-edge structure analysis revealed that the charges were transferred from MnO to Co@NGC, which makes MnO more electrophilic to facilitate the initial electrochemical adsorption of OH- for improving the OER activity. As expected, the as-designed MnO/Co@NGC displays excellent bifunctional ORR/OER activity with a small overpotential gap of only 0.736 V, providing the ZABs with a high trip efficiency of 57.2% as well as excellent cycling stability. This work not only offers a bifunctional ORR/OER electrocatalyst but also further highlights the interfacial charge distribution in oxygen electrocatalysis, affording a promising approach for developing advanced energy-related materials.