Fabrication and characterization of multi-metal co-doped titania films for a water-splitting reaction.

Anchored visible-light-absorbing TiO(2) films have been synthesized by the layer-by-layer method on a quartz slide substrate as a new class of visible light-sensitive photocatalyst. UV-vis, XRD and XPS spectra show that W and Mn enter the TiO(2) lattices and partially substitute for Ti, and that W appears to have a solubility limit into the anatase structure. The Mn and W dopants cause new electronic states above the valence-band edge of pure TiO(2), and the new electronic states may be directly related to the visible-light absorption of doped TiO(2) films. A constant H(2) generation rate is obtained for long periods of time for all the investigated TiO(2) films, and the H(2) production rates for titania films doped with 0.74 at% W (relative to Ti) are 4.1 and 3.3 times higher than that of non-doped TiO(2) under UV and visible light, respectively, as the dopant atoms not only restrict the band gap to the visible region, but also facilitate the detrapping of charge carriers to the surface of the catalyst.