Optimizing Hybrid-phase IrO₂ Catalysts with Ti for Enhanced Oxygen Evolution Reaction for Proton Exchange Membrane...

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, IrO₂. 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 IrO₂-based electrocatalysts. Herein, a hybrid-phase Ti-incorporated IrO₂ electrocatalyst is developed, exhibiting outstanding OER activity (298.8 mV at 100 mA cm^-2) 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 IrO₂ 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.