Enhancing the Oxygen Evolution Reaction Activity via Non-Noble-Metal Substitution in Spin–Orbit Coupled Sr ₂ IrO ₄

Enhancing the oxygen evolution capacity of materials constitutes a pivotal strategy for augmenting electrochemical catalytic efficacy. Here we report enhanced oxygen evolution reaction (OER) activity in Sr₂Ir1-xFexO₄. The incorporation of Fe modifies the electronic structure of Ir and stabilizes its high oxidation state, facilitating the stabilization of reaction intermediates and accelerating the kinetics of the OER. Specifically, Sr₂Ir0.91Fe0.09O₄ requires only 264 mV to reach 10 mA cm⁻² in 1 M KOH, exhibits a Tafel slope of as low as 52.9 mV dec⁻¹, and delivers a 1.9-fold increase in electrochemically active surface area (ECSA). The catalytic activity of Sr₂Ir1-xFexO₄ samples is enhanced through electronic structure alteration of substituting elements, increasing the active site reactivity and oxygen evolution capability. This study provides insights into the design of an OER catalyst through 3d and 5d metal synergies, advancing electrocatalyst development.