Voltage-dependent morphology, wettability and photocurrent response of anodic porous titanium dioxide films

The effects of anodic voltages on the morphology, wettability and photocurrent response of the porous titanium dioxide films prepared by electrochemical oxidation in a hydrofluoric acid (HF)/chromic acid electrolyte have been studied. The porous titanium dioxide films showed an increased surface roughness with the increasing anodizing voltages. By controlling the films morphology and surface chemical composition, the wettability of the porous titanium dioxide films could be easily adjusted between superhydrophilicity and superhydrophobicity. X-ray diffraction (XRD), Raman and UV–vis spectroscopy revealed that the obtained titanium dioxide films were in anatase phase. The titanium dioxide films showed clear photocurrent response, which decreased dramatically with the increase of the anodizing voltages. This study demonstrates a straightforward strategy for preparing porous titanium dioxide films with tunable properties, and especially emphasizes the importance of understanding their morphology/properties relationship.