Sn doped TiO₂ nanotube with oxygen vacancy for highly efficient visible light photocatalysis

Sn doped TiO₂ nanotube with oxygen vacancy (V_o-Sn-TiO₂) was successfully synthesized via a facile hydrothermal process and subsequent annealing in nitrogen atmosphere. The morphology, structure and photocatalytic performance of V_o-Sn-TiO₂ in the degradation of nitrobenzene were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy, nitrogen adsorption-desorption and electrochemical impedance spectra, respectively. The inner diameter, outer diameter and specific surface area of V_o-Sn-TiO₂ are about 5 nm, 15 nm and 235.54 m² g^-1, respectively. The experimental results show that the V_o-Sn-TiO₂ exhibits excellent photocatalytic performance with a maximum degradation rate of 92% in 300 min for nitrobenzene and 94% in 100 min for Rhodamine B and corresponding mineralization rates of 68% and 70% under visible light irradiation. The improved photocatalytic performance is ascribed to the enhanced light absorption and specific surface area as well as the reduced electron-hole pair recombination with the presence of oxygen vacancy and Sn doping in the TiO₂ nanotube.