Nanoconfined Cu─O─Mo Asymmetric Sites Enable Ambient Spontaneous O₂-to-¹O₂ Conversion for Sustainable Water Purification

The selective activation of molecular oxygen (O₂) to singlet oxygen (¹O₂) 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─Mo⁶⁺ dual-site embedded within a nanoconfined membrane is constructed that drives spontaneous O₂-to-¹O₂ 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 O₂ while adjacent Mo⁶⁺ sites stabilize Cu⁺ species and facilitate the direct formation of ¹O₂, 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 O₂ activation, providing an efficient and environmentally benign strategy for advanced water purification.