Fine tuning of phosphorus active sites on g-C3N4 nanosheets for enhanced photocatalytic decontamination

Abstract

Graphitic carbon nitride (gCN) has attracted increasing interest in photocatalysis because of its visible-light-responsive ability, environment-friendliness, low cost and ease of large-scale production. However, its practical application is restricted by its insufficient light absorption, relatively small surface area and low charge separation efficiency. In this work, a post-P-doped gCN nanosheet (gCN-P (post)) with a controllable morphology was successfully synthesized and highly-active P sites were introduced by C/P substitution. The formed porous nanosheet structure greatly increased the specific surface area and exposed more active sites to favor the photocatalytic reaction. gCN-P (post) exhibited excellent visible light photoactivity toward bisphenol A (BPA) degradation with a much higher reaction rate than pristine gCN and other P-doped g-C₃N₄ composites. Doping P resulted in a narrowed band gap of gCN with enhanced light-harvesting and improved reduction capacity of electrons, which facilitated the reduction of molecular oxygen and the formation of more high-powered oxidative species. The post-P doping could maintain the morphology of gCN nanosheets with a high yield and simultaneously optimize the electronic orbital distribution of the triazine ring. The high BPA mineralization efficiency and preferable photostability capacity further confirmed its application potential. This work provides a promising approach for efficient water and wastewater treatment with rationally designed visible-light-responsive photocatalysts.