$$\hbox {Sn}⁴⁺$$ Sn 4 + -doped $$\hbox {TiO}₂$$ TiO 2 nanorod array film with enhanced visible light photocatalytic activity

(hbox {Sn}⁴⁺)-doped (hbox {TiO}₂) nanorod array film (NAF) on the fluorine-doped tin oxide (FTO) conducting glass was successfully synthesized using the facile hydrothermal method. The NAF photocatalysts were characterized by the scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV–Vis diffuse reflectance spectra (DRS). The SEM images showed that both doped and pure (hbox {TiO}₂) NAFs exhibited a good nanorod array structure. (hbox {Sn}⁴⁺)-doped (hbox {TiO}₂) NAF still maintains rutile crystal structure, which was identical to that of pure (hbox {TiO}₂) sample. By means of the DRS measurement, it was found that the (hbox {Sn}⁴⁺) doping in (hbox {TiO}₂) nanorod could induce an obvious enhancement of visible light absorption owing to the introduction of doping energy level in the band gap of (hbox {TiO}₂). The degradation of methyl orange (MO) demonstrated that the (hbox {Sn}⁴⁺)-doped (hbox {TiO}₂) NAF exhibited an enhanced photocatalytic activity than pure (hbox {TiO}₂) NAF under the visible light ((lambda >400;hbox {nm})) irradiation, which should be attributed to the enhanced visible light response and improved separation efficiency of photogenerated carriers of (hbox {Sn}⁴⁺)-doped (hbox {TiO}₂).