The influence of mechanical processing on the photoelectrochemical behaviour of TiO2 powders

Anatase TiO(2) powders have been subjected to mechanical treatment for selected time intervals. The mechanical processing induced a gradual microstructural refinement, accompanied by a two-stage phase transformation into TiO(2) II phase and then rutile. Thin film electrodes were then prepared by depositing the processed powders on Ti supports from an organic suspension. The electrodes were successively exposed to irradiation with Hg lamps and the photoelectrochemical response of the powders evaluated in terms of efficiency of photocurrent generation. The experimental findings clearly show that the efficiency of the photoelectrochemical response drops as the duration of mechanical treatment increases. A suitably developed model indicates that the observed efficiency decrease is mostly due to the formation of nanostructured phases consequent to the mechanical deformation at impacts. (C) 2008 Elsevier B.V. All rights reserved.