One-step synthesis of Fe–N–S-tri-doped TiO2 catalyst and its enhanced visible light photocatalytic activity

Fe–N–S-tridoped TiO2 was synthesized through simple one step sol–gel reactions in the presence of ammonium ferrous sulfate. The resulting materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, diffuse reflectance spectrum and surface photovoltage spectroscopy. Results revealed that Fe and S were incorporated into the lattice of TiO2 by substituting for some Ti atoms and N for O atoms in the lattice of TiO2. Tri-doping with Fe, N and S could inhibit the phase transformation of TiO2 from anatase to rutile, restrain the growth of crystallite sizes, extended the light absorption into the visible region and separate photoinduced charge carriers. The visible photocatalytic activity of Fe–N–S-tridoped TiO2 was higher than that of N-TiO2 and P25 TiO2. The enhanced photocatalytic activity was attributed to the small crystallite size, high crystallinity, the intense light absorption in visible region, narrow band gap and high separation efficiency of photoinduced charge carriers.