Evaluating the Stability of Active Manganese Sites During Electrochemical Reactions by Cyclic Voltammetry

Manganese oxides are a promising class of electrocatalysts for renewable energy devices, such as fuel cells. Mn(III) ions with e g electron filling of − 1 are the active sites for manganese-based electrocatalysts. However, Mn(III) sites may be disproportionated during electrochemical reactions, thus reducing the number of Mn(III) active sites and decreasing the catalytic activity of manganese oxides. In this work, we developed a facile cyclic voltammetry method to monitor the evolution of Mn(III) sites on a series of manganese oxides under “working” conditions. We proposed a descriptor S Mn(III) to describe the stability of Mn(III). Our simulated and experimental results show that the higher is S Mn(III) , the higher the active Mn(III) density, and the higher the electrocatalytic activity of the manganese oxide electrocatalyst.