Synergy of nitrogen vacancies and partially broken hydrogen bonds in graphitic carbon nitride for superior photocatalytic hydrogen evolution under visible light

Hydrogen-bond engineering and nitrogen vacancies have been proposed separately to significantly tune the photoactivities of g-C3N4. Nevertheless, the intrinsic relationships between hydrogen bonds, nitrogen vacancies and photo-performance are still unclear. Herein, partially broken hydrogen bonds and nitrogen vacancies were simultaneously introduced into a g-C3N4 framework (BNCNx) via a facile magnesium-etching approach. BNCN20 showed a remarkably high hydrogen evolution rate of 1941.7 mu mol h(-1) g(-1) under lambda >400 nm irradiation with satisfactory photostability, which was respectively 13 times and 3 times that of g-C3N4 with hydrogen bonds (HCN) and g-C3N4 with partially broken hydrogen bonds (BCN), as well as higher than that of most reported metal-free g-C3N4 photocatalysts. The apparent quantum efficiencies (AQEs) of BNCN20 at 405 and 420 nm were 9.58% and 8.57%, respectively. This work demonstrated that the synergy of partially broken hydrogen bonds and nitrogen defects was an effective strategy to engineer the electronic structures of g-C3N4 with outstanding physicochemical properties for photocatalysis.

Automated summary

This study demonstrates that the synergistic effect of partially broken hydrogen bonds and nitrogen defects is an effective strategy to enhance the photocatalytic performance of g-C3N4. The introduction of these defects leads to a hydrogen evolution rate of 1941.7 mu mol h(-1) g(-1) with satisfactory photostability.