Construction of oxygen-doped g-C3N4/BiOCl (S-scheme) heterojunction: Efficient degradation of tetracycline in wastewater

Abstract

Graphitic phase carbon nitride (g-C3N4) demonstrates significant promise in the photocatalytic degradation of organic pollutants, but the rapid recombination of photogenerated electron-hole pairs seriously restricts its degradation capacity. In this study, an innovative heterostructural anion regulation strategy based on g-C3N4 was proposed to significantly enhance the degradation performance of tetracycline. Initially, we regulated the electron configuration of g-C3N4 through O doping to optimize the active sites at the reaction interface. Subsequently, the S-scheme heterojunction was constructed by introducing BiOCl to stimulate the pumping effect and form efficient build-in electric field electron channels. The oxygen-doped g-C3N4/BiOCl (OCN/BiOCl) heterojunction material obtained through aforementioned modification exhibited a degradation efficiency of 89.33 % towards 20 mg·L−1 tetracycline (90 min light reaction, 30 min dark reaction), which was 2.5 times that of conventional g-C3N4 catalyst. In particular, density functional theory calculations and ultraviolet photoelectron spectroscopy jointly revealed the unique chemical environment and electronic structure between OCN and BiOCl due to the formation of the build-in electric field, thereby providing enhanced pathways for the migration of photogenerated currents. Meanwhile, the heterostructure significantly reduced the transport distance of photo-induced charge and minimizes the internal transmission resistance. It enhances the efficiency of separating photogenerated electrons and hole pairs, which is the key mechanism for greatly improving the photocatalytic degradation performance of OCN/BiOCl materials. In summary, the hetero-anion regulation strategy proposed in this study addresses the issue of rapid recombination of photogenerated charges in g-C3N4, providing a new perspective for efficient control of organic pollutants in the environment driven by g-C3N4 photocatalyst.