Enhanced photocatalytic performance of Ag–Bi4Ti3O12 nanocomposites prepared by a photocatalytic reduction method

Abstract

Bi4Ti3O12 nanoparticles with size of 60–90 nm were decorated with smaller-sized Ag nanoparticles (12–25 nm) by a photocatalytic reduction method. The as-prepared Ag–Bi4Ti3O12 composites were systematically characterised by X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, electrochemical impedance spectroscopy, photoluminescence spectroscopy and photocurrent response. It is demonstrated that the decoration of Bi4Ti3O12 with Ag nanoparticles leads to an effective separation of photogenerated electron–hole pairs. RhB was chosen as the target organic pollutant to evaluate its degradation behaviour over Ag–Bi4Ti3O12 composites under simulated sunlight irradiation. Compared to bare Bi4Ti3O12, Ag–Bi4Ti3O12 composites exhibit a significantly enhanced photocatalytic activity and the highest photocatalytic activity is observed for 5·2 wt% Ag–Bi4Ti3O12. The first-order reaction rate constant suggests that the photocatalytic activity of 5·2 wt% Ag–Bi4Ti3O12 is about 2·4 times higher than that of bare Bi4Ti3O12. AO, ethanol and BQ were, respectively, used as the scavengers of h+, •OH and • to investigate their effect on the degradation of RhB. It is found that only AO has an important suppression on the dye degradation, from which it is concluded that h+ is the dominant reactive species causing the dye degradation.