Modulating Location of Single Copper Atoms in Polymeric Carbon Nitride for Enhanced Photoredox Catalysis

Introducing single-atom metals (SAMs) is a promising strategy to improve photocatalysis of polymeric carbon nitride (PCN), but current studies are limited to loading SAMs on the surface of PCN to serve as active sites. Herein, we report an intercalation-structured hollow carbon nitride sphere composed of carbon nitride nanosheets (HCNS) with atomically dispersed Cu1N3 moieties embedded within nanosheets (Cu1@HCNS) prepared by a facile molecular assembly approach. It exhibits far superior photoredox catalysis to the pristine HCNS and the modified HCNS with Cu1N3 moieties anchored on the surface of nanosheets (Cu1/HCNS) for solar hydrogen production (3261 mu mol g(-1) h(-1) rate with 7.1% of apparent quantum yield), in which the embedded single-atom Cu acts as a modifier to effectively modulate the electron structure and remarkably promote interfacial charge transfer of PCN rather than act as active sites to facilitate surface reaction. It can be extended to the nonoxygen coupling of benzylamine and derivants to corresponding imines, and the unexpectedly high reaction rate is achieved. The promoting effect strongly depends on the location of single-atom Cu in the PCN, and the coordination method is a very effective strategy to introduce single-atom metals in terms of the improvement in photocatalysis of PCN owing to the intensified metal-PCN interaction. This work opens up a window for further improving the photocatalytic efficiency of carbon nitride in terms of solar fuel production and clean organic synthesis.