g-C3N4 nano-fragments as highly efficient hydrogen evolution photocatalysts: Boosting effect of nitrogen vacancy

Abstract N vacancy modified g-C3N4 nano-fragments were facilely prepared through thermal treatment method. The declined size and thickness of resultant g-C3N4 nano-fragments make it possess quantum confinement effect. The synergistic effect of N vacancy and quantum confinement effect endows resulting g-C3N4 nano-fragments with bigger surface area, stronger light response ability and improved migration effect of photoinduced charge. Not only that, the existence of quantum confinement effect remedies the shortcoming that reduced intrinsic conduction band potential was caused by N vacancy, and the conduction band position was easily adjusted. When N vacancy modified g-C3N4 nano-fragments were used to produce H2, the H2 evolution rate of the best sample (nano-CN5) was 5.9 folds more than bulk g-C3N4 and kept admirable stability of performance, structure and feature. Clearly, the present work develops a useful strategy for adjusting conduction band position of g-C3N4 and a meaningful thought for changing band gap of other photocatalysts.