Shape-controllable synthesis and morphology-dependent photocatalytic properties of AgBr photocatalysts

AgBr photocatalysts with ellipsoid, polyhedral and ball-like morphologies were successfully synthesized by simply adjusting external experimental conditions such as the content of surfactant and the Br source. The samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoemission spectroscopy, Brunauer–Emmett–Teller and UV–Vis diffuse reflectance spectroscopy to determine the structure, morphology and optical property. To clarify the relationship between morphology and photocatalytic activity, the photocatalytic performances of AgBr photocatalysts were systematically evaluated by photodegradation of three organic contaminants including rhodamine B, methylene blue and methyl orange in aqueous solutions under visible-light irradiation. Compared with ellipsoid AgBr samples, polyhedral AgBr and ball-like AgBr samples exhibited higher photocatalytic activities. The enhancement visible-light photocatalytic activity could be attributed to higher surface area, strong visible light absorption, the surface plasmon resonance and its synergistic effect on the photosensitive AgBr. Furthermore, a possible photocatalytic mechanism of AgBr photocatalysts was also discussed, revealing ·O2− and h+ are main reactive species and free ·OH radicals in solution also contribute to the degradation reaction.