Synthesis and Enhanced Photocatalytic Activity of Rare Earth Ion (Ce3+, Nd3+, Pr3+ or Sm3+) Doped Bi2WO6 Microspheres for Rhodamine B Degradation

Pure and rare earth ion (Ce3+, Nd3+, Pr(3+)or Sm3+) doped Bi2WO6 microspheres were synthesized via a facile hydrothermal process. Their physical and chemical properties were characterized by using X-ray diffraction, UV-vis diffuse reflectance spectroscopy, scanning electron microscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy and N-2 adsorption-desorption isotherm analysis. Results showed that rare earth ion doping into Bi2WO6 leaded to decreased crystallite size, narrowed band gap and increased surface area. The organic dye rhodamine B was chosen to explore the photocatalytic activity of all the samples. It had been found that Nd3+ doped Bi2WO6 showed extremely higher photocatalytic activity compared to the pure Bi2WO6. The improved photocatalytic activity had been attributed to the reduced size of crystallite, enhanced visible light absorption and enlarged surface area which resulted in the effective separation of the photogenerated electron hole pairs. The sample also had a good stability after six times of cycling experiments. In addition, the photocatalytic mechanism had been inferred by the radical-trapping experiments. It had verified that the photogenerated holes play a major role in the photocatalysis process.