Effect of Vanadia Doping and Its Oxidation State on the Photocatalytic Activity of TiO2 for Gas-Phase Oxidation of Ethene

Single phasic anatase titania with up to 10 mol % vanadium doping, having a particle size of about 12 rim, was synthesized by a sol-gel route and its photocatalytic behavior evaluated for the photo-oxidation of ethene using sunlight-type excitation. Incorporation of vanadia in the titania lattice was established using techniques like XRD, XPS, surface area analysis, TEM, DR-UV-visible spectroscopy, Raman spectroscopy, and FTIR. Vanadium doping led to a red shift in the UV-visible absorbance spectra compared to pristine titania, thus enhancing the absorption in the visible region. Synthesized nanotitania and vanadia-doped titania exhibit enhanced photocatalytic activity compared to the commercial bulk anatase TiO2, with maximum activity obtained for the 5 mol % vanadium-doped titania sample, which was attributed to an optimum concentration of V4+ and V5+ species. The role of these species in enhancement of catalytic activity and reaction mechanism has been discussed.