Preparation of novel BiOBr/CeO2 heterostructured photocatalysts and their enhanced photocatalytic activity

Abstract

Novel BiOBr/CeO₂ heterostructured photocatalysts were synthesized by a simple solvothermal method. The photocatalysts compared with pure BiOBr and pure CeO₂ are more photoactive in photocatalytic oxidation of rhodamine B (RhB), methylene blue (MB) and bisphenol A (BPA) under visible light irradiation. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) absorption spectroscopy and photoluminescence (PL) spectroscopy. The 5 : 1 BiOBr/CeO₂ shows the highest visible-light photocatalytic activity for degradation of RhB and is highly stable during photodegradation. The remarkably enhanced photocatalytic activities could be mainly attributed to the low recombination ability between photo-induced electrons and holes, which results from the formation of a heterojunction structure between BiOBr and CeO₂. The active species trapping experiments indicate that the primary oxidative species in the reaction system are the photogenerated hole (h⁺) and superoxide radicals (·O₂⁻). A possible mechanism for the photocatalytic activity enhancement was also put forward on the basis of the experimental results.