Sr‐Stabilized IrMnO₂ Solid Solution Nano‐Electrocatalysts with Superior Activity and Excellent Durability for Oxygen Evolution Reaction in Acid Media

Abstract The development of cost‐effective catalysts for oxygen evolution reaction (OER) in acidic media is of paramount importance. This work reports that Sr‐doped solid solution structural ultrafine IrMnO₂ nanoparticles (NPs) (≈1.56 nm) on the carbon nanotubes (Sr‐IrMnO₂/CNTs) are efficient catalysts for the acidic OER. Even with the Ir use dosage 3.5 times lower than that of the commercial IrO₂, the Sr‐IrMnO₂/CNTs only need an overpotential of 236.0 mV to drive 10.0 mA cm⁻² and show outstanding stability for >400.0 h. Its Ir mass activity is 39.6 times higher than that of the IrO₂ at 1.53 V. The solid solution and Sr‐doping structure of Sr‐IrMnO₂ are the main origin of the high catalytic activity and excellent stability of the Sr‐IrMnO₂/CNTs. The density function theory calculations indicate that the solid solution structure can promote strong electronic coupling between Ir and Mn, lowering the energy barrier of the OER rate‐determining step. The Sr‐doping can enhance the stability of Ir against the chemical corrosion and demetallation. Water electrolyzers and proton exchange membrane water electrolyzers assembled with the Sr‐IrMnO₂/CNTs show superb performance and excellent durability in the acid media.