W-N Bonds Precisely Boost Z-Scheme Interfacial Charge Transfer in g-C3N4/WO3 Heterojunctions for Enhanced Photocatalytic H2 Evolution

Exploring and achieving precise electron-transfer channels in the interface of Z-scheme heterojunctions are essential and have been considered as immense challenges. A strategy to precisely connect the valence band (VB) site of g-C3N4 (CN) with the conduction band (CB) site of WO3 through the tungsten- nitrogen (W-N) bond was developed to create a chemically bonded Z-scheme heterojunction photocatalyst. Because of this reason, the photogenerated electrons from the CB site of WO(3 )could be accurately and directly injected into the VB site of CN, following the direct Z-scheme charge separation pathways. The photocatalytic hydrogen production rate of optimal CNWB was 482 mu mol h(-1), 4.3 times higher than that of CN/WO3 without an N-W bond (CNWU). The CNWB also shows better photocatalytic hydrogen evolution activity than the previous CN/WO(3 )systems. Theoretical and experimental results further confirm that the newly formed N-W bonds become metallic, which could act as atomic-level interfacial channels and precisely accelerate Z-scheme interfacial electron transfer and shorten the electron-transfer distance, thus substantially boosting photocatalytic H-2 generation. This work paves a way to design and synthesize the chemically bonded Z-scheme interface with atomic precision for interesting photocatalytic applications in the future.

Automated summary

Precise electron transfer in Z-scheme heterojunctions has been a challenge, but a new strategy of chemically bonding the valence band site of g-C3N4 with the conduction band site of WO3 shows promising results in boosting photocatalytic hydrogen generation.