Electrochemical Surface Modification of Layered IrTe₂Films for Enhanced Oxygen Evolution Reaction

Iridium ditelluride (IrTe₂) as a two-dimensional (2D) transition metal dichalcogenide (TMDC) has attracted significant attention as a promising catalyst for oxygen evolution reactions (OERs). Although its electrochemical performance has been explored, detailed surface–state analyses are essential to fully elucidate the underlying catalytic mechanisms. Here, we fabricated surface-modulated IrTe₂ thin films via repeated cyclic voltammetry and demonstrated that the formation of Ir–O–Te surface bonds play a critical role in enhancing OER activity. The modified surface provides a favorable electronic environment that stabilizes catalytically active Ir–OH and Ir–OO species. Moreover, ambient-pressure X-ray photoemission spectroscopy (APXPS) under water vapor atmosphere revealed that the oxidized surface facilitates the adsorption and dissociation of water molecules. This process leads to partial reduction of Te atoms, facilitating the formation of hydroxyl bonds (−OH) and tuning the local charge distribution. As a result, the partially oxidized IrTe₂ film (Oxd-20) exhibited a markedly improved OER performance, with an overpotential of 354 mV at 10 mA/cm², outperforming pristine IrTe₂ and benchmark iridium films. These findings provide mechanistic insight into the enhanced OER activity of IrTe₂, highlighting the pivotal role of surface–state modulation in activating 2D telluride catalysts.