Enhancing the visible light absorption of titania nanoparticles by S and C doping in a single-step process

We report the synthesis of carbon coated and sulfur doped titania nanoparticles using a continuous, single-step laser pyrolysis technique. We employed air as oxidant and C2H4 as laser energy transfer agent (sensitizer)/carbon donor, both carrying the TiCl4 vapors as a titania precursor. The volatile (CH3)2S2 was used to introduce sulfur as dopant in the nanopowders. The incorporation of C and S atoms in nanopowders with anatase dominant phase and with average particle diameter between 18 and 25 nm was performed through the addition of S2(CH3)2 and C2H4 to the reactive precursor mixtures. The samples were characterized by: EDX, XRD, TEM, XPS and UV-Vis spectroscopy. By the introduction of the sulfur precursor, the anatase-to-rutile ratio within the resulted TiO2-based nanoparticles decreased, as well as their bandgap energy values which are also lower than those of commercial TiO2 Degussa P25.