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

Abstract

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 pre-fabricated 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.