Nanoconfined Cu─O─Mo Asymmetric Sites Enable Ambient Spontaneous O ₂ ‐to‐ ¹ O ₂ Conversion for Sustainable Water Purification

Abstract The selective activation of molecular oxygen (O 2 ) to singlet oxygen ( 1 O 2 ) represents a sustainable route for green oxidation yet remains fundamentally challenged by spin‐forbidden transitions and kinetic trapping of superoxide intermediates. Here, an asymmetric Cu + ─O─Mo 6+ dual‐site embedded within a nanoconfined membrane is constructed that drives spontaneous O 2 ‐to‐ 1 O 2 conversion under ambient conditions, achieving 95.2% selectivity without additional energy inputs. Experimental and theoretical analyses reveal that electron‐rich Cu + sites facilitate spin‐selective electron transfer to adsorbed O 2 while adjacent Mo 6+ sites stabilize Cu + species and facilitate the direct formation of 1 O 2 , bypassing the conventional superoxide desorption bottleneck. The nanoconfined environment further concentrates local reactants, yielding a 0.053 ms −1 degradation rate constant, exceeding most Fenton‐like systems. The system maintains operational stability for 146 h in continuous‐flow filtration with ultralow metal leaching (<0.02 mg L −1 ) and operational cost (0.01 USD L −1 ), enabling over 95% removal of diverse micropollutants in complex water matrices. This work establishes a new catalytic paradigm merging atomic‐scale asymmetric site design with nanoconfinement engineering for sustainable and selective O 2 activation, providing an efficient and environmentally benign strategy for advanced water purification.