Enhanced photocatalytic activity of Bi25FeO40-Bi2WO6 heterostructures based on the rational design of the heterojunction interface

Based on the rational design of the heterojunction interface, a novel and efficient Bi25FeO40-Bi2WO6 heterostructure photocatalyst was successfully constructed by a facile hydrothermal process, using prefabricated Bi2WO6 nanoflakes as Bi3+ source and the second-phase material. The as-prepared photocatalyst was characterized by powder X-ray diffraction (XRD), FT-IR spectrum, energy dispersive spectrometry (EDS), X-ray photoelectron spectrum (XPS), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The photocatalytic performance of the Bi25FeO40-Bi2WO6 heterostructure under the UV-visible light irradiation was investigated, which showed that such Bi25FeO40-Bi2WO6 heterojunctions possessed a higher photocatalytic ability than the mechanical mixing product and the single-phase sample (Bi25FeO40 and Bi2WO6). This enhanced photocatalytic efficiency might be attributed to the matching band positions, close interfacial connection, and face-to-face contact mode of heterojunction interface. In addition, a possible photocatalytic decomposition mechanism and the separation process of photoinduced electrons and holes were discussed at length.