Synthesis and photocatalytic mechanism of visible-light-driven AgBr/g-C3N4 composite

g-C3N4 is a well-known visible-light-active photocatalyst for the degradation of environmental pollutants. However, its photocatalytic activity is restricted by the small specific surface area and the e−/h+ recombination rate. In order to improve the photocatalytic performance of g-C3N4, AgBr/g-C3N4 composite photocatalyst has been designed. The as-prepared AgBr/g-C3N4 was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible spectrophotometer (UV–Vis) and room temperature photoluminescence (PL). The photocatalytic activity was evaluated by the photodegradation of methyl orange (MO) under simulated visible-light irradiation. The results show that g-C3N4 is porous structure with a large specific surface area of loading AgBr nanoparticles greatly improves the photocatalytic activity. The AgBr content is optimized to 25 wt%, where the degradation rate of MO can reach 90% after 30 min. The enhancement in photocatalytic performances is mainly attributed to the effective production and transfer of e−/h+ for AgBr can absorb the visible light. Moreover, ·O2− is demonstrated to be the dominant radical for the photocatalytic degradation of MO.