Modulating Carrier Oxygen Vacancies to Enhance Strong Oxide‐Support Interaction in IrO₂/Nb₂O_5‐x Catalysts for Promoting Acidic Oxygen Evolution Reaction

Abstract Given the pronounced dissolution of electrocatalysts in acidic environments, the quest for effective oxygen evolution reaction (OER) electrocatalysts suitable for proton exchange membrane (PEM) water electrolyzers persists as a formidable challenge. In this investigation, catalysts are synthesized by creating oxygen vacancies within various metal oxides (Nb 2 O 5‐x , Ta 2 O 5‐x , ZrO 2‐x , TiO 2‐x ) through plasma‐assisted method, thereby facilitating the immobilization of IrO 2 onto these defect‐rich surfaces. The findings unveil that IrO 2 /Nb 2 O 5‐x manifests reduced overpotentials during acidic OER, achieving an overpotential down to 225 mV@10 mA cm −2 , coupled with outstanding durability at multicurrent densities exceeding 200 h, attributed to strong oxide‐support interaction (SOSI) between the IrO 2 catalyst and Nb 2 O 5‐x substrate. Density functional theory (DFT) computations uncover intensified binding affinities between IrO 2 and Nb 2 O 5‐x , thus modulating the central energy levels of Ir's d orbitals toward favorable OER conditions, consequently bolstering the electrocatalytic activity and stability of the composite catalyst. Furthermore, employing IrO 2 /Nb 2 O 5‐x as a PEM electrolyzer anode enables consistent operation at 1000 mA cm −2 for 200 h, with an Ir content of only 0.2852 mg cm −2 and an energy consumption of 4.34 kWh Nm −3 H 2 . This achievement substantially lowers the cost of hydrogen production to US$ 0.96 per kilogram, underscoring its potential for practical applications.