W-doped CaMnO_2.5 and CaMnO₃ electrocatalysts for enhanced performance in oxygen evolution and reduction reactions

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 CaMnO_2.5 electrocatalysts. Introduction of tungsten cation to replace B-site manganese up to 3% in CaMn_1-xW_xO_y (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.