P-N Bonds-Mediated Atomic-Level Charge-Transfer Channel Fabricated between Violet Phosphorus and Carbon Nitride Favors Charge Separation and Water Splitting.

Heterostructures are widely employed in photocatalysis to promote charge separation and photocatalytic activity. However, their benefits are limited by the linkages and contact environment at the interface. Herein, violet phosphorus quantum dots (VPQDs) and graphitic carbon nitride (g-C 3 N 4 ) are employed as model materials to form VPQDs/g-C 3 N 4 heterostructures by a simple ultrasonic pulse excitation method. The heterostructure contains strong interfacial P-N bonds that mitigate interfacial charge-separation issues. P-P bond breakage occurs in the distinctive cage-like [P9] VPQD units during longitudinal disruption, thereby exposing numerous active P sites that bond with N atoms in g-C 3 N 4 under ultrasonic pulse excitation. The atomic-level interfacial P-N bonds of the Z-scheme VPQDs/g-C 3 N 4 heterostructure serve as photogenerated charge-transfer channels for improved electron-hole separation efficiency. This results in excellent photocatalytic performance with a hydrogen evolution rate of 7.70 mmol g -1  h -1 (over 9.2 and 8.5 times greater than those of pure g-C 3 N 4 and VPQDs, respectively) and apparent quantum yield of 11.68% at 400 nm. Using atomic-level chemical bonds to promote interfacial charge separation in phosphorene heterostructures is a feasible and effective design strategy for photocatalytic water-splitting materials.