Fabrication of self-organized titanium oxide microcones by anodization

초록

Anodic titanium oxides, which are chemically stable and have excellent (photo-) properties, have been used for a long time in multiple applications. They have a significant impact on the development of dye-sensitized solar cells(DSSCs), water splitting, photocatalysis, gas sensors and so on. Since large surface area is a critical factor to determine catalytic properties of TiO2 structure, there have been much studied in the formation of various morphology of TiO2 micro-/nanostructure. For example, TiO2 with a morphology of nanotubes, nanowires, nanoparticles and nanorods have been produced structures of. The microcone structures of anodic metal oxides have been mainly studied in niobium oxides. We have found that titanium oxide microcones can be prepared by anodization under specific electrochemical conditions. The anodization was carried out in an acidic electrolyte containing H3PO4 and HF at constant voltage. The microcones structure was solely formed by anodization at 45-75 V, whereas flower-like or barrier type morphology was synthesized when the applied voltage is higher or lower than the optimized voltage. A morphology of titanium oxide microcones was characterized with scanning electron microscopy(SEM), showing that the microcones anodized at 60 V have the largest surface area among all samples. Cyclic voltammetry shows that the microcones have a certain peak, corresponding to the reaction of Ti2O3(s) + H2O → 2TiO2(s) + 2e- + 2H+ (E = -0.755 V). X-ray diffraction(XRD) confirms that the microcones consist of TiO2 crystalline anatase phase.