Optimizing Hybrid-phase IrO Catalysts with Ti for Enhanced Oxygen Evolution Reaction for Proton Exchange Membrane Water Electrolysis.

To realize a sustainable energy transition, water electrolysis-particularly proton exchange membrane water electrolysis (PEMWE)-holds significant promise. However, practical deployment is hindered by the cost and instability of the anode catalyst, IrO. Recent studies indicate that tuning the Ir─O bond distance, via doping or composite formation, is key to enhancing the oxygen evolution reaction (OER) performance of IrO-based electrocatalysts. Herein, a hybrid-phase Ti-incorporated IrO electrocatalyst is developed, exhibiting outstanding OER activity (298.8 mV at 100 mA cm) and stability over 25 h. This improvement originates from asymmetric interatomic interactions introduced by Ti, as revealed by combined experimental X-ray analyses and theoretical modeling. Ti incorporation induces tensile strain along the z-axis in IrO motifs, effectively reducing the average Ir─O bond distance and thereby enhancing OER activity. In situ X-ray absorption spectroscopy further confirms that at 1.5 V (vs. RHE), the elongated Ir─O bond facilitates ─OOH* intermediate formation while suppressing Ir dissolution, contributing to superior stability. These findings underscore the critical role of Ir─O bond engineering in balancing activity and durability, offering strategic insights for the rational design of high-performance OER catalysts for renewable energy technologies.