Preparation, Structural Characterization and Visible-Light-Responsive Photocatalytic Performance of Lanthanum-doped Bismuth Oxide

Lanthanum doped Bi2O3 (La-Bi2O3) photocatalysts were prepared by impregnation method. The doping quantity of lanthanum, crystalline phase structures and spectral properties of as-prepared photocatalysts were characterized by X-ray fluorescence (XRF), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectrophotometry (UV-Vis) and photoluminescence spectroscopy (PL). The enhanced visible-light activity was tested by the photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP). Results of XRD show that appropriate amounts of lanthanum adulteration can effectively prevent the phase transformation of Bi2O3 from tetragonal to monoclinic. UV-Vis DRS results indicate an extension of light absorption into the visible region (higher than 550 nm). The doped lanthanum partially substitutes bismuth in the lattice of Bi2O3, which exists in the form of Bi-O-La chemical bond. And a new complex metal oxide compound (La0.176Bi0.824O1.5) appears in the catalysts, which could inhibit the recombination between photoelectrons and holes, leading to enhanced photocatalytic quantum efficiency. Furthermore, it is found that Bi2O3 doped with lanthanum of 3% (in mole ratio) has the superior photocatalytic performance for 2,4-DCP.