Synergetic promotion on photoactivity and stability of W18O49/TiO2 hybrid

Hybrid photocatalysts were constructed by mixing W18O49 with commercial TiO2 (P-25) and tested for photodegradation of pollutants (methyl orange and phenol). W18O49 synthesized by alcohothermal method possesses urchin-like structure, high surface area of 178 m(2) g(-1) and wide light absorption in 200-800 nm. Although W18O49 alone shows low photoactivity, the hybrid shows significant synergetic promotion. The activity of W18O49(10 Wt%)/TiO2 under UV-vis light and W18O49(90 wt%)/TiO2 under visible light is 2.43 (2.64) and 1.31 (1.52) times of calculated value without considering the synergy for the degradation of MO (phenol), respectively. Controlled experiments indicate .O-2- from reduction of O-2 by photo-induced electrons is the key active species in the photodegradation. The synergy was attributed to the well-matched band structure of two semiconductors that enhances charge separation, with electrons moving to W18O49 and holes to TiO2, as confirmed by photo-deposition of Au and PbO2. Furthermore, W18O49/TiO2 is much more active than WO3/TiO2 attributed to the good reductive capability and wide light absorption of oxygen vacancies in W18O49. Moreover, the unstable W18O49 shows excellent stability in the hybrid. (C) 2013 Elsevier B.V. All rights reserved.