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

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.