Boosting Photocatalytic Overall Water Splitting Activity of Phosphorene Through Five‐Coordinate Passivation Enabled by Carbene Addition

ABSTRACT Phosphorene is a promising two‐dimensional semiconductor for solar‐driven redox reactions, yet its practical deployment is severely restricted by rapid degradation under ambient conditions. Conventional covalent functionalization typically forms phosphorus–carbon single bonds (P─C), leaving phosphorus atoms in a four‐coordinate environment and thus failing to fully quench the intrinsic reactivity associated with one residual unpaired electron. Here, we develop a selective strategy to achieve five‐coordinate passivation of phosphorene by constructing phosphorus–carbon double bonds (P═C) through a one‐step photochemical carbene addition reaction. Using a carbene precursor, adamantane groups are grafted onto phosphorene to afford a robust P═C‐bonded architecture. Comprehensive spectroscopic analyses, together with density functional theory (DFT) calculations, validate the preferential formation of the P═C bonds. The resulting P═C‐passivated phosphorene exhibits markedly improved ambient stability compared to the pristine and four‐coordinate‐passivated phosphorene. When utilized as a metal‐free photocatalyst, the P═C‐passivated phosphorene enables highly efficient overall water splitting without sacrificial agents under visible light, delivering record‐high evolution of H 2 and H 2 O 2 with rates of up to 612 and 658 µmol h −1 g −1 , respectively, along with excellent cycling stability.