Novel adsorption-photocatalysis integrated bismuth tungstate modified layered mesoporous titanium dioxide (Bi2WO6/LM-TiO2) composites

Abstract

Using cetyltrimethylammonium bromide (CTAB) as the soft template and titanium sulfate as the titanium source, the layered mesoporous TiO2 (LM-TiO2) was prepared by the novel precipitation-peptization method, then bismuth tungstate was synthesized and coupled with layered mesoporous titanium dioxide by the hydrothermal process to obtain adsorption-photocatalysis integrated Bi2WO6/LM-TiO2 composites. The surface morphology, transmission morphology and elemental mapping, particle size, crystal phase composition, ultraviolet absorption band, fluorescence intensity, functional group structure, element composition and valence state of the samples were characterized using scanning electron microscopy (SEM), transmission electron microscope (TEM), laser particle size analyzer, X-ray diffraction (XRD), ultraviolet visible absorption spectrum (UV–Vis-Abs), Molecular fluorescence spectrophotometer (PL) and X-Ray photoelectron spectroscopy (XPS), respectively. Taking methyl orange as the target substance, the adsorption and photocatalytic performances of the samples were studied. The results indicate that Bi2WO6/LM-TiO2 composites have excellent adsorption and photocatalytic degradation performances. When irradiated with a 500 W metal halide lamp for 20 min, the removal rate of methyl orange by 8% Bi2WO6/LM-TiO2 reaches 93.60% which is greatly improved compared with simple LM-TiO2, and is twice as that of P25. By coupling LM-TiO2 with Bi2WO6, the composites show a spherical structure, and the crystallinity does not change significantly. Moreover, the light absorption band edge has a certain red shift and the photogenerated electron-hole recombination is restrained, thereby improving the photocatalytic performance.