Improved photocatalytic activity of dysprosium-doped Bi2O3 prepared by sol–gel method

Bi2O3 and dysprosium-doped Bi2O3 photocatalysts with different molar ratio of Dy/Bi (1/100, 2/100, 3/100 and 4/100) were prepared by a sol–gel method. The photocatalysts prepared were characterized by Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), UV/vis diffuse reflectance, X-ray photoelectron spectroscopic techniques and surface photovoltage spectroscopy, respectively. The results show that dysprosium-doped Bi2O3 with 3/100 Dy prepared has the highest BET surface area, pore volume, the smallest pore size. XRD spectra of dysprosium-doped Bi2O3 catalysts calcined at 773 K are composed of monoclinic and tetragonal phase. Doping Dy into Bi2O3 increases the BET surface area and decreases the crystal size and the band gap of doped Bi2O3 photocatalysts, induces binding energy value of Bi 4f7/2-shift and promotes the photoinduced charge separation rate. Of all of the photocatalysts prepared among the experimented compositions, dysprosium-doped Bi2O3 with 3/100 Dy possesses the best photocatalytic activity and the underlying reason was discussed.