Abstract
It is here demonstrated that proton-intercalation via negative potential biases enhance the rate constant of methylene blue (MB) photo-electrocatalytic de-colorization on n-type tungsten trioxide hydrate (WO 3 ·0.33H 2 O as prepared by hydrothermal synthesis), rather than the positive potential bias in promoting the charge separation of photo-generated electrons/holes. Due to the generation of W(V) and W(IV) hydroxyl species with smaller band gaps (in comparison with W(VI)) and the electrochemical activation of WO 3 ·0.33H 2 O, negatively biased proton intercalation into WO 3 ·0.33H 2 O clearly enhances its photo-electrocatalytic activity for MB de-colorization, including its visible-light photo-electrocatalytic activity. A possible scheme for promoting the photocatalytic activity of WO 3 ·0.33H 2 O through proton intercalation under constant potential biases is proposed and discussed. The photocatalytic de-colorization rate of MB on UV100-TiO 2 is significantly decreased under the same potential biases due to the difficulty in proton-intercalation. © 2013 Elsevier B.V.