Ag/AgBr/g-C3N4: A highly efficient and stable composite photocatalyst for degradation of organic contaminants under visible light

Graphical abstract: Ag/AgBr/g-C3N4 composite photocatalysts displayed excellent photocatalytic activities on the degradation of methyl orange (MO) under visible light. The improved photocatalytic performance and stability of Ag/AgBr/g-C3N4 originated from the synergetic effects of AgBr/g-C3N4 interface and metallic Ag nanoparticles. ·O2−, one of the reactive species, was responsible for the photodegradation of MO compared to H+ and ·OH. - Highlights: • Novel Ag/AgBr/g-C3N4 composite photocatalyst was reported. • Ag/AgBr/g-C3N4 had novel energy band combination between AgBr and g-C3N4. • Synergetic effects of AgBr/g-C3N4 interface and metallic Ag nanoparticles. • Electron trapping role of metallic Ag dominated the stability of Ag/AgBr/g-C3N4. - Abstract: Novel Ag/AgBr/g-C3N4 composite photocatalysts were constructed via deposition–precipitation method and extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and UV–vis diffuse reflectance spectroscopy (DRS). Under visible light (λ > 420 nm), Ag/AgBr/g-C3N4 composite photocatalysts displayed much higher photocatalytic activities than those of Ag/AgBr and g-C3N4 for degradation of methyl orange (MO). 50% Ag/AgBr/g-C3N4 presented the best photocatalytic performance, which was mainly attributed to the synergistic effects of AgBr/g-C3N4 interface and the in situ metallic Ag nanoparticles for efficiently separating electron–hole pairs. Furthermore, Ag/AgBr/g-C3N4 remained good photocatalytic activity through 5 times of cycle experiments. Additionally, the radical scavengers experiment indicated that ·O2− was the main reactive species for the MO degradation under visible light