Fabrication of TiO2 nanotubes with extended periodical morphology by alternating-current anodization

Highly uniform TiO2 nanotube arrays with regular periodical sidewall morphology were fabricated by both alternating-voltage (AV) and alternating-current (AC) anodization methods. It was revealed that the AC anodization provided a better control to the sidewall morphology than the AV anodization. Various bamboo-shaped nanotube arrays were prepared by using AC anodization with different current functions. Dye-sensitized solar cells (DSSCs) fabricated using different TiO2 nanotube arrays showed that the AC anodization with square-wave driving current gave the highest photo energy conversion efficiency.

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► We demonstrate a novel alternating current method for the fabrication of TiO2 nanotube arrays.
► TiO2 NT with different tube morphologies can be achieved by applying different current signals.
► The method can be applied to improve the photo-energy conversion efficiency of DSSC.
► This new method has potentials in the fabrication of complex 3D TiO2 architectures.