Designing novel step-scheme heterojunction g-C3N4/TMCs/GO with effective charge transfer for photocatalytic degradation of organic pollutant under visible light

Abstract

Designing and constructing step-scheme (S-scheme) heterojunction structure has attracted wide attention on account of its particular photocatalytic performance on removing environmental pollutants. Herein, a novel ternary composite photocatalyst of graphitic carbon nitride (g-C3N4)/TiO2 mesocrystals (TMCs)/graphene oxide (GO) with S-scheme heterojunction structure was prepared by solvent evaporation method. A positive cooperative effect between the g-C3N4 and TMCs was constructed to promote the light harvesting, while the GO was introduced to further improve the adsorption capacity and charge transfer efficiency, which favored the degradation of rhodamine B (RhB) and tetracycline hydrochloride by the ternary composite having high-efficient photocatalytic capacity under visible light. Experiments and characterizations confirmed that the high-efficient photocatalytic performance could be attributed to the unique hierarchical structure of TMCs, high redox ability and enhanced efficiency of charge transfer through S-scheme route, well carrier mobility and adsorption capacity of GO, and promoted light harvesting of composite. The S-scheme charge transfer mechanism suggested that the photo-generated holes and electrons could be remained in lower CB and higher VB with stronger redox capacity. This work offered a paradigm for construction and design of novel photocatalyst with TiO2 mesocrystal-based S-scheme heterojunction structure and high-efficient activity in organic pollutant degradation.