Multi-layer three-dimensionally ordered bismuth trioxide/titanium dioxide nanocomposite: synthesis and enhanced photocatalytic activity.

Taking polystyrene latex spheres (PS) and EO20PO70EO20 (P123) as dual templates, and TiO2 was used as substrate, a series of multi-layer three dimensionally ordered macroporous (3DOM) composites Bi2O3/TiO2 were successfully synthesized with sol-gel method and post-processing calcination. The fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), UV-vis diffuse reflectance (UV-vis/DRS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM) and nitrogen adsorption-desorption measurements were employed to analyze the crystalline phase, chemical composition, morphology, and surface physicochemical properties of as-synthetized samples. The results showed that as-composites were provided with obvious crystalline phase structure and periodically highly uniform ordered macroporous structure with mesoporous walls; moreover, of which was multi-layer three dimensionally ordered structure. As a result of unique optical properties of Bi2O3 and composite material structural characteristic being propitious to reactant molecular transmission and diffusion, the photocatalytic activities of 3DOM Bi2O3/TiO2 were enhanced, and the sample 3DOM Bi2O3/TiO2-2 was significantly higher than that of direct photolysis, P25, Bi2O3, and other 3DOM Bi2O3/TiO2-X (X=1, 3, 4) during the photocatalytic degradation of crystal violet under multi-modes such as UV, visible light, simulated solar light, and microwave-assisted irradiation. The centrifugal samples water solution phase of TOC analysis indicated that water solution products formed with continued ultraviolet radiation, the intermediates eventually mineralized, volatilized, or were converted to other products. In addition, the photocatalytic activity of 3DOM Bi2O3/TiO2-2 composite was basically kept even after three cycles. Meanwhile, the possible photocatalytic reaction mechanism of as-synthesized material based on the experimental results was proposed.