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

Graphical Best of the bunch: Four different phases of IrO 2 /MnO 2 are synthesized by using a simple reduction-oxidation method, which can improve oxygen evolution reaction (OER) performance. IrO 2 /α-MnO 2 shows the best OER performance among the four different IrO 2 /MnO 2 catalysts. 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 .