W-Doped CaMnO2.5 and CaMnO3 Electrocatalysts for Enhanced Performance in Oxygen Evolution and Reduction Reactions

Abstract

Sluggish kinetic of oxygen redox reactions, namely, oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is often a main reason for the low efficiency of oxygen electrocatalysts. It hinders the wide-spread applications of renewable energy conversion devices. For those electrocatalysts that are made of transition metal oxides, poor electrical conductivity further compounds the problem. In this study, we show a strategy, in which low level of dopants is used to increase the electrical conductivity of both perovskite CaMnO3 and reduced, oxygen-deficient perovskite CaMnO2.5 electrocatalysts. Introduction of tungsten cation to replace B-site manganese up to 3% in CaMn1-xWxOy (x = <0.03; y = 2.5 and 3) results in enhanced ORR and OER performance, due to the increase of electrical conductivity of these oxide catalysts via double-exchange mechanism. The concept of using low-level dopants to increase the electrical conductivity, thus the activity, should be a quite useful strategy for designing the transition metal oxide electrocatalysts for enhanced performance in OER and ORR.