Metal‐Oxygen Octahedra Regulation of Iridium‐Based Perovskites for Efficient and Durable Acidic Water Oxidation

Abstract The dissolution and inactivation of anodic oxygen evolution reaction (OER) electrocatalysts remain significant barriers to the development of acidic water electrolysis. Here, the activity and stability of BaIrO ₃ (BIO) perovskite are enhanced through the controlled regulation of metal‐oxygen octahedra via B‐site substitution with Co (BICO). During OER process, the dissolution of Ba and Co leads to the formation of highly active IrCoO _x nanoparticles on the amorphous surface layers of BICO. The introduction of Co not only increases the concentration of high‐valence Ir species with high activity but also prevents the excessive oxidation and dissolution of Ir by taking over its oxidation role during the reaction. Theoretical calculations reveal a substantial reduction in the energy barrier of the rate‐determining step (RDS) after Co doping. BICO‐2 electrocatalyst demonstrates exceptional OER performance, requiring an overpotential of 216 mV to achieve a current density of 10 mA cm ⁻² , while maintaining continuous operation for over 140 h without significant degradation, and boasting a stability number (S‐number) of 4.3 × 10 ⁵ . Additionally, BICO‐2 exhibits excellent activity and durability in proton exchange membranes (PEM) water electrolysis. This work introduces a novel approach for designing and fabricating efficient, long‐lasting electrocatalysts, offering significant insights for advancing acidic water electrolysis technologies.