Tuning the band gap of TiO2 by tungsten doping for efficient UV and visible photodegradation of Congo red dye

W@TiO2 nanoparticles (0, 2, 4, and 6 mol%) were synthesized by the sol gel method and their photocatalytic activity was evaluated for the degradation of Congo red dye under UV-vis light irradiation. The photodegradation activity of 6 mol% catalyst in visible light is found to be better than UV light as well as standard commercial titania Degussa P25. The developed thin film of catalyst over glass substrate demonstrated a clear advantage of separation and recyclability of photocatalyst.89