Subnanometric Iridium Clusters Atomically Enrooted on Non‐Stoichiometric Tungsten Oxides for Boosting Acidic Oxygen Evolution Reaction

Abstract The inherent thermodynamic instability of subnanometric clusters hinders their practical applications in electrocatalysis. Addressing this requires precise regulation of metal‐support interaction to firmly anchor subnanometric clusters onto suitable supports without compromising the exposure of active sites. Herein, a stabilization strategy utilizing non‐stoichiometric engineering is proposed to develop a series of enrooted‐type metallic Ir supported on tungsten oxides, including W 18 O 49 (WO 2.72 ), W 20 O 58 (WO 2.9 ), and WO 3 . Among these, the optimal Ir/WO 2.72 catalyst exhibits exceptional acidic oxygen evolution reaction (OER) performance with a low overpotential of 259 mV at 10 mA cm −2 , high mass activity of 1202.5 A g Ir −1 , and robust stability over 150 h. Experimental characterizations and theoretical calculations reveal that the unique enrooted structure and oxygen‐deficient WO 2.72 support significantly enhance the anchoring stability and dispersion of supported Ir clusters, effectively confining them to subnanometer dimensions (0.8 nm). More importantly, the enrooted Ir atoms and WO 2.72 support synergistically modulate the electronic structure of Ir clusters, reducing their electron density and optimizing the adsorption of oxygen‐containing intermediates, thereby boosting OER performance. This work advances the development of stable supported subnanometric cluster catalysts and offers important theoretical insights into the understanding of metal‐support interaction mechanisms at the subnanometric scale.