title: Transition from anodic titania nanotubes to nanowires: arising from nanotube growth to application in dye-sensitized solar cells.
abstract: Anodic formation of titania nanowires has been interpreted using a bamboo-splitting model; however, a number of phenomena are difficult to explain with this model. Herein, transition from nanotubes to nanowires is investigated by varying the anodizing conditions. The results indicate that the transition requires a large number of hydrogen ions to reduce the passivated area of tube walls, and therefore can be observed only in an intermediate chemical dissolution environment. Accordingly, a model in terms of stretching and splitting is proposed to interpret the transition process. The model provides a basis to suppress the nanowires with surface treatments before anodization and to clear the nanowires with an ultrasonication process after anodization. The nanotube-nanowire transition also arises when the tubes are directly used in dye-sensitized solar cells. Treatment with titanium tetrachloride solution for about 10 h is found to be effective in suppressing the nanowires, and thus improving the photovoltaic properties of the solar cells.
authors: School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
authors: Lidong
authors: L
authors: Sun
authors: Sam
authors: S
authors: Zhang
authors: Xiu
authors: X
authors: Wang
authors: Xiao Wei
authors: XW
authors: Sun
authors: Duen Yang
authors: DY
authors: Ong
authors: Xiaoyan
authors: X
authors: Wang
authors: Dongliang
authors: D
authors: Zhao