The self-organized TiO₂ nanotube layers have attracted considerable scientific and technological interest over the past 10 years, which are motivated for their possible range of applications including photo-catalysis, solar cells, hydrogen generation and biomedical uses [1]. The synthesis of 1D TiO₂ nanotube structure is carried out by a conventional electrochemical anodization of Ti sheet. The main drawback of TiO₂ is its applicability in the UV light (wavelengths < 390 nm). In order to enhance the efficiency, TiO₂ has been doped by N [2] or C [3] to shift its absorption into the visible light.

Except of doping, one of the major issues to extend the functional range of nanotubes is to coat homogenously tube interiors by a secondary material. It has been shown that additional ultrathin surface coating of TiO₂ by secondary materials such as Al₂O₃ [4], ZnO [5] or MgO [6] annihilates electron traps at the TiO₂ surface and thus increases the concentration of the photogenerated charge carriers. The presentation will focus in detail on the coating of the nanotube arrays by various secondary materials using ALD. The deposited materials influence strongly photo-electrochemical properties of nanotube layers. Experimental details and some very recent photocatalytic [7, 8], sensing [9] and solar cell [10] results will be presented and discussed.

References:

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8. S. Ng et al., Adv. Mater. Inferf., in press
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10. M. Krbal et al., Nanoscale 9 (2017) 7755