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

Abstract

Anchored visible-light-absorbing TiO₂ 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 TiO₂ 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 TiO₂, and the new electronic states may be directly related to the visible-light absorption of doped TiO₂ films. A constant H₂ generation rate is obtained for long periods of time for all the investigated TiO₂ films, and the H₂ 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 TiO₂ 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.