A Mechanistic Insight into the Acidic-stable MnSb 2 O 6 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 O 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 O and Mn O revealed that the rate-determining step for OER on MnSb O is the direct formation of Mn =O from Mn -H O by the 2H /2e process. This process avoids the rearrangement of adjacent Mn intermediates, leading to outstanding stability and activity.