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).

Atomic layer deposition (ALD) has been shown to be an effective technique to coat TiO₂ nanotube layers homogenously with secondary materials. Ultrathin surface coating of TiO₂ by secondary materials such as Al₂O₃ [2], ZnO [3] or MgO [4] annihilates electron traps at the TiO₂ surface and thus increases the concentration of the photogenerated charge carriers.

This presentation will focus in detail on the coating of the nanotube layers with different (high) aspect ratios by various secondary materials using ALD. We will show initial photo-electrochemical results for anodic TiO₂ nanotubes employed as highly ordered electron-conductive supports for host materials coated using ALD with secondary materials to enhance light absorbing capabilities of such hybrid systems. Experimental details and some very recent photocatalytic [5, 6], sensing [7] and solar cell [8] results will be presented and discussed.

References:

1. J. M. Macak et al., Curr. Opin. Solid State Mater. Sci., 2007, 1-2, 3.
2. R. Zazpe et al., Langmuir, 2016, 41, 32.
3. A. Ghobadi et al., Sci. Rep. 2016, 6, 30587.
4. H. Park, et al., J. Electroceram. 2009, 23, 146.
5. H. Sopha et al., Appl. Mater. Today, 9 (2017) 104.
6. S. Ng et al., Adv. Mater. Interfaces 2017, 1701146.
7. S. Ng et al. Adv. Eng. Mater., 2017, 1700589
8. R. Zazpe et al., submitted.