Metal-free π-conjugated hybrid g-C3N4 with tunable band structure for enhanced visible-light photocatalytic H2 production

Development of low-cost and efficient photocatalytic materials with visible-light response is of urgent need for solving energy and environmental problems. Here, a metal-free two-dimensional (2D) pi-conjugated hybrid g-C3N4 photocatalyst with tunable band structure was prepared by a novel one-pot bottom-up method based on a supersaturated precipitation process of urea and triethanolamine (TEOA) solution. The microstructure of the hybrid g-C3N4 is revealed to be a compound of periodic tri-s-triazine units grafted with N-doped graphene (GR) fragments. From experimental evidence and theoretical calculations, the two different pi-conjugated fragments in the hybrid g-C3N4 material are proved to construct a 2D in-plane junction structure, thereby expanding the light absorption range and accelerating the interface charge transfer. The pi-conjugated electron coupling in the 2D photocatalyst eliminates the grain boundary effect, and the coupled highest occupied molecular orbital (HOMO) effectively promotes the separation of photo-induced charge carriers. Compared with the g-C3N4 prepared by the conventional method, the visible-light H-2 production activity of the optimized sample is enhanced by 253 %. This work provides a new strategy of constructing metal-free g-C3N4 hybrids for efficient photocatalytic water splitting. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

A metal-free two-dimensional pi-conjugated hybrid g-C3N4 photocatalyst with tunable band structure was successfully prepared, showing enhanced visible-light H-2 production activity. This study provides a new strategy for constructing efficient photocatalytic water splitting materials by developing metal-free g-C3N4 hybrids.