The influence of mechanical processing on the photoelectrochemical behaviour of TiO(2) powders

Anatase TiO2 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 TiO2 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.