g-C sub(3)N sub(4) modified Bi sub(2)O sub(3) composites with enhanced visible-light photocatalytic activity

Novel g-C sub(3)N sub(4) modified Bi sub(2)O sub(3) (g-C sub(3)N sub(4)/Bi sub(2)O sub(3)) composites were synthesized by a mixing-calcination method. The samples were characterized by thermogravimetry (TG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), UV-vis diffuse reflection spectroscopy (DRS), photoluminescence (PL) and photocurrent-time measurement (PT). The photocatalytic activity of the composites was evaluated by degradation of Rhodamine B (RHB) and 4-chlorophenol (4-CP) under visible light irradiation (>400 nm). The results indicated that the g-C sub(3)N sub(4)/Bi sub(2)O sub(3) composites showed higher photocatalytic activity than that of Bi sub(2)O sub(3) and g-C sub(3)N sub(4). The enhanced photocatalytic activity of the g-C sub(3)N sub(4)/Bi sub(2)O sub(3) composites could be attributed to the suitable band positions between g-C sub(3)N sub(4) and Bi sub(2)O sub(3). This leads to a low recombination between the photogenerated electron-hole pairs. The proposed mechanism for the enhanced visible-light photocatalytic activity of g-C sub(3)N sub(4)/Bi sub(2)O sub(3) composites was proven by PL and PT analysis.