Sm3+-Doped Bi2O3 Photocatalyst Prepared by Hydrothermal Synthesis

Bi2O3 and sm(3+)-doped Bi2O3 visible-light-active photocatalysts with different Sm3+ loadings (0.5, 1.0, and 2.0 wt%) were synthesized by a hydrothermal method. The structural properties of the prepared catalysts were studied by X-ray diffraction (XRD), BET surface area, UV/Vis diffuse reflectance (DRS), FTIR, and X-ray photoelectron (XPS) spectroscopic techniques. The XRD spectra of the Sm-doped Bi2O3 catalysts calcined at 550 degrees C show only the characteristic peaks of Bi2O3. A high red shift in the range 450-600 nm was detected in the DRS band, leading to a large decrease in the band-gap energy from 2.82 to 2.0 eV. This red shift increased with increasing Sm content. XPS results revealed that Sm interacted with Bi2O3, wherein both Bi and Sm were in the +3 oxidation state. The photocatalytic activities of the catalysts were evaluated for the degradation of methylene blue and phenol under solar irradiation. Of all of the catalysts prepared, the Sm3+-doped Bi2O3 with a Sm loading of 1 wt% gave the best photocatalytic activity.