In Situ Synthesis of V4+ and Ce3+ Self-Doped BiVO4/CeO2 Heterostructured Nanocomposites with High Surface Areas and Enhanced Visible-Light Photocatalytic Activity

In order to achieve high performance in visible light photocatalysis, V4+ and Ce3+ self-doped BiVO4/CeO2 heterostructured nanocomposites with high surface areas were prepared using the templating approach employing mesoporous silica MCM-41 as the hard template. X-ray photoelectron spectroscopy (XPS) spectra have demonstrated the presence of plentiful V4+ and Ce3+ species in the nano composites accompanied by the formation of oxygen vacancies. The presence of V4+ species is further identified by the electron spin resonance (ESR) spectrum. Furthermore, the BiVO4 and CeO2 could be affecting each other by arousing the structural changes in the formed nanocomposites. The V4+ and Ce3+ self-doped 0.4BiVO(4)/0.6CeO(2) nanocomposite with the surface area as large as 78.35 m(2)/g exhibits the highest photocatalytic activity for the rhodamine B (RhB) and methyl orange (MO) degradation and photoelectrochemical performances. The enhanced photocatalytic mechanism is systematically studied via UV-vis diffuse reflectance spectra (DRS), photoluminescence (PL) spectra, transient photocurrent responses, and electrochemical impedance spectroscopy (EIS) spectra. The remarkable enhanced photocatalytic activity could be mainly attributed to the formed heterojunction nanostructures, the presence of defect states induced by oxygen vacancies, and self-doped V4+ and Ce3+ centers, as well as high surface areas. A possible photocatalytic mechanism over the V4+ and Ce3+ self-doped BiVO4/CeO2 nanocomposites is proposed based on the active species trapping experiments and calculated energy band structures.