Sm 3+ ‐Doped Bi 2 O 3 Photocatalyst Prepared by Hydrothermal Synthesis

Bi 2 O 3 and Sm 3+ ‐doped Bi 2 O 3 visible‐light‐active photocatalysts with different Sm 3+ 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 Bi 2 O 3 catalysts calcined at 550 °C show only the characteristic peaks of Bi 2 O 3 . 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 Bi 2 O 3 , 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 Sm 3+ ‐doped Bi 2 O 3 with a Sm loading of 1 wt % gave the best photocatalytic activity.