Visible Light Photocatalytic Performance of Bi2O3/TiO2 Nanocomposite Particles

Visible-light photoactive Bi2O3/TiO2 catalysts were prepared by sol-hydrothermal process. The as-prepared samples were characterized by XRD, TEM, XPS, UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), FTIR, N-2 adsorption-desorption and ESR. Compounding with low amounts of Bi2O3 could effectively inhibit the phase transformation from anatase to rutile. UV-Vis DRS showed an extension of light absorption into the visible region. ESR results indicated that the active species (center dot OH) was generated with visible illumination (lambda>420 nm). It was found that the optimal dosage of bismuth was 2.0wt%. Proper amount of bismuth species compounded on the TiO2 surface could improve the anatase crystallinity, which could inhibit the recombination between photoelectrons and holes, leading to enhanced photocatalytic quantum efficiency. Meanwhile, the enhanced visible-light activity was tested by the photocatalytic degradation of 4-chlorophenol (4-CP). Furthermore, the generated intermediates were identified using gas chromatograph-mass spectrometer and Bi2O3-photosensitization mechanism under visible light illumination was proposed.