Cyclic Voltammetry on Rutile IrO₂(110): Effects and Origin of Lateral Interactions

Iridium oxide is a benchmark catalyst for the oxygen evolution reaction in acidic media, yet its electrochemical characteristics, particularly the broad redox peak in cyclic voltammetry (CV), remain poorly understood. Herein, we investigate the origin of this feature on rutile IrO₂(110) using a density functional theory-based microkinetic model. The model successfully reproduces the broad peak at around 1.1 V versus the reversible hydrogen electrode, which is attributed to OH*/O* redox transitions at μ₂ (bridge) sites. The broad feature originates from strong lateral interactions at μ₂ sites due to electron-density redistribution via shared Ir atoms. In addition, the model reproduces experimental OER trends and identifies the O* at μ₁ (top) sites as a key OER precursor. These findings highlight the critical role of lateral interactions in shaping electrochemical properties on metal oxide electrodes and underscore the importance of incorporating such effects into the atomistic modeling and interpretation of electrocatalytic processes.