Fabrication of Rh-doped Bi2O3 with Enhanced Photocatalytic Performance by Sol-gel Method

Abstract Bi2O3 and Rh-doped Bi2O3 photocatalysts with different molar ratio of Rh/Bi (1%, 2% and 3%) were prepared by a sol-gel method. The photocatalysts prepared were studied by BET surface area, X-ray diffraction (XRD), UV/Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopic (XPS) techniques and surface photovoltage spectroscopy (SPS), respectively. The results show that 2% sample prepared has the highest BET surface area, pore volume, the smallest pore size. The XRD spectra of the Rh-doped Bi2O3 catalysts calcined at 773 K is composed of monoclinic and tetragonal phases. Rh-doped Bi2O3 absorbs much more light than Bi2O3 in the visible light region. XPS results reveal the binding energy of Bi 4f7/2 and O 1s of 2% and 3% samples shifts to a lower value. Doping Rh into the lattice of Bi2O3 influences the photoinduced charge separation rate of Bi2O3. Rh-doped Bi2O3 with 2% Rh possesses the best photocatalytic activity and the underlying reason was discussed.