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 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 MnSb 2 O 6 was successfully prepared and investigated as a catalyst for OER in a sulfuric acid solution (pH of 2.0). A comprehensive mechanistic comparison between MnSb 2 O 6 and Mn 3 O 4 revealed that the rate‐determining step for OER on MnSb 2 O 6 is the direct formation of Mn IV =O from Mn II −H 2 O by the 2H + /2e − process. This process avoids the rearrangement of adjacent Mn III intermediates, leading to outstanding stability and activity.