(Invited) TiO₂ Nanotube Arrays: Photoelectrochemical and Photocatalytic Applications

Abstract

TiO 2 nanomaterials have over the last 30 years attracted tremendous scientific and technological interest. Main research direction using TiO 2 in functional applications are still the use in photocatalysis e.g. for the direct splitting of water into H 2 and O 2 to generate the potential fuel of the future, hydrogen, or the use in Grätzel type solar cells. In order to achieve a maximum turn-over rate (by creating a high surface area), usually nanoparticles are used either suspended or compacted to a photoelectrode. Over the past decades various 1D and highly defined TiO2 morphologies were explored for the replacement of nanoparticle networks and were found in many cases superior to nanoparticles. Nanotubes or wires can be grown by hydrothermal or template methods, or even more elegantly, by self-organizing anodic oxidation. The latter is not limited to TiO 2 but to a full range of other functional oxide structures on various metals and alloys can be formed. These advanced and doped morphologies can be grown on conductive substrates as ordered layers and therefore can be directly used as functional electrodes (e.g. photo-anodes). The presentation will focus on these highly ordered nanotube arrays of TiO 2 and discuss most recent progress in synthesis and modification for photocatalytic and photoelectrochemical for H 2 generation. Literature: (reviews): - P. Roy, S. Berger, P. Schmuki, Angew. Chem. Int. Ed. (2011), 2904 - K. Lee, A. Mazare, P. Schmuki, CHEMICAL REVIEWS, 114 (2014) 9385