Fabrication of a TiO2 photocatalyst by anodic oxidation of Ti in an acetic acid electrolyte

We anodized Ti substrates in an aqueous acetic acid solution to produce photocatalytic TiO2 films. The TiO2 films were comprised of the anatase phase, but the crystallinity and photocatalytic activity were low, in contrast to films produced by Ti anodization in a sulfuric acid electrolyte. After annealing, the anatase film crystallized and the photocatalytic activity was greatly enhanced. For the anodizations carried out in 0.5 and 2 M acetic acid, nonzero current was maintained for the duration of anodization, unlike the other concentrations. We interpret this phenomenon as the layered structure formation from the holes on the substrate surface. Highly crystallized anatase TiO2 therein was thought to mainly contribute to photocatalysis.