Effect of surface microstructure of titanium sheet on the photocatalytic activity of its oxide film

Titanium oxide film was formed by thermal oxidation directly on titanium sheet. Pretreatments on titanium sheet were carried out using annealing in Argon at 873 K, 973 K and 1073 K for 5 min, 30 min and 100 min, respectively. Photocatalytic performance of titanium oxide film was examined by measuring the degradation of methylene blue. The crystallographic orientation distribution of titanium sheet was analyzed by SEM/EBSP technique whereas the crystalline structure of titanium oxide film was characterized by XRD. Development of recrystallization texture on titanium sheet gained during the annealing, in which stored energy was lowered, was proved to facilitate formation of the preferable oxide film with high photocatalytic property during oxidation. However, grain size of titanium sheet was found to be another important and effective factor since grain boundaries were testified to be the channels for the diffusion of oxygen in the thermal oxidation reaction. Grain coarsening of titanium sheet is probably a detriment to high photocatalytic activity of its oxide film.