A Mechanistic Insight into the Acidic‐stable MnSb2O6 for Electrocatalytic Water Oxidation

The abundant, active, and acidic‐stable catalysts for the oxygen evolution reaction (OER) are rare to the 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 MnSb2O6 was successfully prepared and investigated as a catalyst for OER in a sulfuric acid solution (pH of 2.0). A comprehensive mechanistic comparison between MnSb2O6 and Mn3O4 revealed that the rate‐determining step for OER on MnSb2O6 is the direct formation of MnIV=O from MnII−H2O by the 2H+/2e− process. This process avoids the rearrangement of adjacent MnIII intermediates, leading to outstanding stability and activity.