Orbital Fine‐Tuning of d/p‐Band Centers Enables Highly Preferential Single‐Electron Oxygen Activation

The single‐electron photocatalytic reduction of molecular oxygen to superoxide radicals (O 2 •− ) represents the rate‐determining step in environmental photochemistry, yet achieving high selectivity toward this pathway remains a formidable challenge. Here, we introduce a conceptually driven orbital‐hybridization strategy to precisely regulate the d/p orbitals of polymeric phenylethynylcopper (PECu) through chlorine doping. Rather than acting as a conventional heteroatom dopant, Cl − serves as an “orbital fine‐tuner”, enhancing the coordination polarization of C≡C─Cu units and shortening the Cu─Cu ladder spacing to construct an efficient metal–metal charge‐transfer (MMCT) channel. This interfacial electronic engineering markedly improved d/p‐band center proximity (Δ ε d‐p ), thereby optimizing the adsorption and activation of O 2 intermediates at alkyne active sites. The optimized PCC photocatalyst exhibits exceptional selectivity for the O 2 → O 2 •− single‐electron reduction pathway, achieving a superoxide yield of 471.38 µmol/L and significantly enhanced water decontamination performance. This work extends conventional band‐center engineering from activity optimization to highly preferential single‐electron oxygen activation by identifying d/p‐band‐center proximity as a key electronic descriptor governing selective single‐electron O 2 reduction.