Optical investigation on sulfur-doping effects in titanium dioxide nanoparticles

The sulfur-doping (S-doping) effects in TiO₂ nanoparticles are investigated by means of Raman spectroscopy and UV–Vis spectroscopy with different S-doping levels (10 and 50%). Raman spectra indicate that the rutile and anatase phases dominate for the low S-doped (10%) and high S-doped (50%) TiO₂ nanoparticles, respectively. The variation of phase with different S-doping levels has been ascribed to the different S-doping processes into TiO₂ nanoparticles. In addition, an extra absorption band is observed in both the S-doped TiO₂ nanoparticles. With increasing S-doping level from 10 to 50%, the extra absorption band shows a blue-shift from 470 to 445 nm, which may be ascribed to the variation of phase from rutile to anatase for TiO₂.