Defect-selective modulation of pyrrolic nitrogen active sites and the induction of atomic-level interfacial bridge Zn–N–C in heterojunction for superior solar hydrogen production

Establishing robust atomic-level interfaces, particularly through the selective modulation of surface active sites within heterojunctions to achieve superior solar energy conversion, remains largely unexplored. Herein, sulfur vacancy sites (V S ) in ZnIn 2 S 4 (ZIS) are selected, driven by the interaction between unsaturated zinc sites and the nitrogen-rich sites of g-C 3 N 4 , forming a step-scheme (S-scheme) heterojunction. The defect-induced interfacial Zn–N–C bonds not only provide rapid channels at the atomic level, thereby lowering the energy barrier for charge transfer, but also selectively tune the highly active pyrrolic N site to enhance H 2 evolution. Furthermore, molecular dynamics simulations (MD) combined with density functional theory (DFT) calculations reveal that V S regulates the pyrrolic N sites within the heterojunction, leading to a reduction in the Gibbs free energy for hydrogen production. Kinetic analysis by carrier transport activation energy (CTAE) indicates that the charge transfer energy barrier is accelerated, decreasing from 211.20 eV for ZIS/CN-360 % to 155.71 eV for V S -ZIS/CN-360 %. Consequently, the designed catalyst significantly enhances the H 2 yield (27.94 mmol g −1  h −1 ) in the absence of platinum. This work emphasizes the importance of generating defect-induced interfacial atomic channels, as well as changes in the surface microenvironment, which underscore the significance of defect heterostructures in promoting the photocatalytic process.