Sol-solvothermal preparation and characterization of (Yb, N)-codoped anatase–TiO2 nano-photocatalyst with high visible light activity

(Yb, N)-codoped anatase–TiO2 nanosheets were successfully synthesized by a modified sol-solvothermal process and characterized by X-ray diffraction, transmission electron microscopy, N2 physical adsorption–desorption, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, UV–vis absorbance spectroscopy and photoluminescence spectroscopy. Results revealed that (Yb, N)-codoping significantly improved the photoactivity for degradation of methylene blue (MB) in aqueous solution under UV and visible light irradiation, respectively, as compared with N-doped and undoped TiO2. N atoms incorporated with the TiO2 lattices to form O–Ti–N and Ti–O–N structures, which induced the formation of localized occupied states in the band gap, accounting for the visible light adsorption. Yb-doping effectively inhibited the recombination of photogenerated charge carriers and significantly improved textural properties. Additionally, (Yb, N)-codoping effectively inhibited phase transformation from anatase to rutile and N element running off, and further increased the surface hydroxyl. The enhanced visible light activity for (Yb, N)-codoped TiO2 was ascribed to a synergetic effect of the increase in the visible light absorption, charge separation efficiency, surface hydroxyl, anatase crystallinity, and adsorption ability to organic pollutants, as well as the improved microstructural properties. (Yb, N)-codoped TiO2 also exhibited a good photochemical stability, and thus had wider application prospects than TiO2.