Boosting the Extra Generation of Superoxide Radicals on Graphitic Carbon Nitride with Carbon Vacancies by the Modification of Pollutant Adsorption for High-Performance Photocatalytic Degradation

Abstract

The adsorption of organic pollutants on the surface defects of photocatalysts can directly change the surface redox reaction to improve the photocatalytic degradation efficiency; however, the interaction mechanism remains unclear. In this study, graphitic carbon nitride (g-C3N4) with C vacancies enabling more C–NHx exposure (HTCN) was synthesized and used to study the effect of organic pollutant adsorption on photocatalytic properties. The exposure of C–NHx distinctly separates the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital of HTCN and avoids the competitive adsorption between O2 and organic pollutants on the HTCN surface, facilitating the generation of O2•– and direct pollutant oxidation by h+. More importantly, the pollutants exactly adsorbed on the HOMO distribution area of HTCN derived from C vacancies further regulate the energy band structure by spontaneous electron transfer, which promotes more electrons to be captured by O2 for O2•– generation and high-performance degradation of pollutants.