d ‐Orbital Single Electron Filling O─O π * Bonds on WO 3 S 1 Sites for Highly Selective Generation of Hydroxyl Radicals

Abstract Hydroxyl radical (•OH) stemming from dissolved oxygen (O 2 ) via photocatalysis is very attractive, but its poor selectivity and generation efficiency greatly limit its application. Herein, a kind of tungsten single site co‐coordinated with O and S atoms (WO 3 S 1 ) is established on ZnIn 2 S 4 (W‐ZIS). The strong interactions in WO 3 S 1 shift the d ‐band center toward the Fermi level, enhancing the adsorption of O 2 . These interactions improve the accumulation of photo‐generated electrons on WO 3 S 1 , facilitating the dissociation of O─O bonds in crucial intermediates and promoting the selective conversion from O 2 into •OH. This brings a state‐of‐the‐art selectivity (40.2%) and generation efficiency (1668.90 mmol. g −1 . L −1 . h −1 ) of •OH production. Experimental results and theoretical simulations have elucidated that O 2 can be reduced by d ‐orbitals single electron ( ↑ , _, _, _, _, _) of WO 3 S 1 transfer to 2 p ‐orbital O─O pi anti‐bonding ( π* : p x and p y ), initially activating O 2 . Additionally, WO 3 S 1 sites facilitate the cleavage of H 2 O, optimizing proton adsorption through W─O orbital coupling in WO 3 S 1 and promoting the transformation of oxygen‐containing intermediates. More importantly, d ‐orbitals single electron can fill O─O π* bond in •OOH intermediate, weakening the covalency of the O─O bond, mitigating the formation of H 2 O 2 and shortening the pathway for •OH generation.).