Influence of the MnO2 Phase on Oxygen Evolution Reaction Performance for Low‐Loading Iridium Electrocatalysts

Abstract Developing high‐performance, low‐loading, Ir‐based electrocatalysts for the oxygen evolution reaction (OER) in acidic media is still a great challenge. Herein, we fabricated an iridium manganese catalyst with only 5 % iridium. The influence of the manganese dioxide phase states (α‐, β‐, γ‐ and δ‐MnO 2 ) on the OER performance of IrO 2 /MnO 2 catalysts was investigated. α‐MnO 2 , as the substrate, can generate smaller iridium particles and more high‐valence‐state iridium to promote OER performance. Therefore, the 5 % IrO 2 /α‐MnO 2 electrocatalyst exhibits excellent electrocatalytic OER performance with a high mass activity of 216.67 A/g Ir and 655.33 A/g Ir at 1.53 V in acidic and alkaline media, respectively, significantly outperforming commercial IrO 2 .