Surface Density-of-States Engineering of Anatase TiO by Small Polyols for Enhanced Visible-Light Photocurrent Generation.

Enhancement of visible-light photocurrent generation by sol-gel anatase TiO films was achieved by binding small polyol molecules to the TiO surface. Binding ethylene glycol onto the surface, enhancement factors up to 2.8 were found in visible-light photocurrent generation experiments. Density functional theory calculations identified midgap energy states that emerge as a result of the binding of a range of polyols to the TiO surface. The presence and energy of the midgap state is predicted to depend sensitively on the structure of the polyol, correlating well with the photocurrent generation results. Together, these results suggest a new, facile, and cost-effective route to precise surface band gap engineering of TiO toward visible-light-induced photocatalysis and energy storage.