A Mechanistic Insight into the Acidic-stable MnSbO for Electrocatalytic Water Oxidation.

The abundant, active, and acidic-stable catalysts for the oxygen evolution reaction (OER) are rare to proton exchange membrane-based water electrolysis. Mn-based materials show promise as electrocatalysts for OER in acid electrolytes. However, the relationship between the stability, activity and structure of Mn-based catalysts in acidic environments remains unclear. In this study, phase-pure MnSbO was successfully prepared and investigated as a catalyst for OER in a sulfuric acid solution (pH of 2.0). A comprehensive mechanistic comparison between MnSbO and MnO revealed that the rate-determining step for OER on MnSbO is the direct formation of Mn=O from Mn-HO by the 2H/2e process. This process avoids the rearrangement of adjacent Mn intermediates, leading to outstanding stability and activity.