Study of new states in visible light active W, N co-doped TiO2 photo catalyst

Highlights: ► Visible light efficient W, N co-doped TiO{sub 2} photo catalysts are prepared by sol–gel. ► Oxygen vacancies are detected in the form of new linkages as N-Ti-O, N-W-O, Ti-O-N and W-O-N. ► W, N co-doped titania has new energy states which narrows the band gap effectively. ► Oxygen vacancies are proved to be the cause for high photo catalytic activity. ► W and N co-doping plays the major role to make the composite thermally stable. -- Abstract: The visible light efficient W, N co-doped TiO{sub 2} photo catalysts are prepared by sol–gel method. New linkages of N, W and O are formed as N-Ti-O, N-W-O, Ti-O-N and W-O-N. Electron paramagnetic resonance illustrates the presence of oxygen vacancies in W, N co-doped TiO{sub 2} acting as trapping agencies for electrons to produce active species. X-ray photoelectron spectroscopy confirms the presence of new energy states. New linkages and oxygen vacancies are proved to be the main cause for the improved photo catalytic performances. W, N co-doped TiO{sub 2} has new energy states which narrow the band gap effectively. W, N co-doped TiO{sub 2} is thermally stable and retains its anatase phase up to 900 °C. 4.5% W, N co-doped TiO{submore » 2} showed superior activity for the degradation of Rhodamine B and 2,4-dichlorophenol as compared to pure titania, Degussa P-25, traditional N-doped TiO{sub 2} and pure WO{sub 3}.« less