Controlled synthesis of Bi2O3/TiO2 catalysts with mixed alcohols for the photocatalytic oxidation of HCHO.

Bi2O3/TiO2 photocatalysts were prepared by a hydrothermal method. The photocatalysts were applied to the catalytic oxidation of indoor formaldehyde vapors under irradiation by an light-emitting diode energy-saving lamp. The characterization methods including Brunauer-Emmett-Teller, X-ay diffraction, UV-vis spectra, scanning electron microscopy, Transmission electron microscopy and X-ray photoelectron spectroscopy analysis were used to investigate the crystalline structure, morphology, specific surface area and porosity. The effects of the preparation conditions, including the type of alcohols, molar ratio and calcination temperature, on the morphology, structure and crystalline phase of the catalyst were also investigated. The results reveal that the morphology could be controlled by using different types of alcohols, especially mixed alcohols. The morphology played a key role in determining the photodegradation efficiency of formaldehyde. According to the experimental results, the Bi2O3/TiO2 catalysts with amorphous particles showed the highest activity. The presence of anatase TiO2 and Bi4(TiO4)3 with a heterojunction structure was the main reason for the high activity, and they were beneficial for increasing the separation of the photogenerated electrons and holes and decreasing their recombination through electron transformations.