Enhancement of photocatalytic activity for WO3 by simple NaOH loading

We found a simple method for preparation of NaOH-loaded WO3 with high photocatalytic activity under visible light irradiation. The sample was characterized with XRD, UV-Vis, VB-XPS, and other methods. From the VB-XPS data, the potentials of bottom of conduction band (CB) and top of valence band (VB) for WO3 were found to be lifted up by NaOH loading. Furthermore, this NaOH-loaded WO3 exhibited marked photocatalytic activity for 2-propanol decomposition into CO2 under visible light irradiation. The activity of 5 wt% of NaOH-loaded WO3 was 120 times higher than that of pure WO3. Possible reasons for the higher activity of the NaOH-loaded WO3 are the raising of the potential of CB and suppression of H2O2 accumulation. More detailed analyses were conducted using the reaction mechanism and potentials of VB and CB. This stable solid-base-loaded WO3 maintains its photocatalytic activity for over 3 months. (C) 2014 Elsevier B.V. All rights reserved.