Semi-metallic TiO2 Nanotubes: Growth, Properties and Applications Seminar
- Time:
- 11:00
- Date:
- 19 June 2015
- Venue:
- Building 27, Room 2001 Chemistry University of Southampton Southampton SO17 1BJ
For more information regarding this seminar, please email Nuria Garcia-Araez at N.Garcia-Araez@soton.ac.uk .
Event details
Robert Hahn presents a seminar as part of the Electrochemistry research group's seminar series.
Self organized nanotubular structures of transition metal oxides grown on their metallic substrates, especially titanium, have attracted great scientific and technological interest due to the possibility to exploit their functional properties (such in photo-catalysis, electro-catalysis, solar energy conversion, DSSCs and as host for Li storage) in nanotubular morphology. In contrast to the conventional way to grow anodic TiO2 nanotubes, which is an optimized electrochemical treatment of Ti in fluoride containing electrolyte (for an overview see [1]) this work reports on the growth of nanotubes by so-called RBA (rapid breakdown anodization).[2] This nanotube growth-process is in comparison extremely fast (seconds instead of hours) and seems to be initiated by a pit. This leads to surface coatings consisting of dense packed bundles of nanotubes with very high aspect ratios (tube length up to 50 micrometer, tube diameter of ~40 nanometer). In addition, this method provides a new route for an insitu electrochemical doping during the growth of TiO2 nanotubular layers with various transition metals to adjust the electronic levels in the material which is important for charge transfer reactions through the semiconductor/electrolyte interface [3]. The second part of the presentation will demonstrate that alternatively the electronic and optical properties [4] of these TiO2 nanotubes can be significantly modified, showing semi-metallic behavior by a high temperature reduction treatment in acethylene or ammonia creating a suitable platform for highly conductive surface area electrodes which is important i.e. sensing, methanol oxidation or supercap applications [5]
References:
[1] S. Berger, R. Hahn, P. Roy, P. Schmuki Phys. Status Solidi B247, 10,2424 (2010).
[2] R. Hahn, J. M. Macak, P. Schmuki, Electrochem. Commun.,9, 947 (2007).
[3] M. Stark, R. Hahn, M.S. Killian, P. Schmuki Catal. Sci. Technol., 3, 1765 (2013).
[4] R. Hahn, F. Schmidt-Stein, J. Salonen, S. Thiemann, Y.Y. Song, J. Kunze, V.-P. Lehto, P Schmuki, Angewandte Chemie - International Edition 48(39), 7236 (2009).
[5] S. A. Al-Thabaiti, R. Hahn, N. Liu, R. Kirchgeorg, S. So, P. Schmuki, S. N. Basahel, S. M. Chemistry Communication 50, 7960 (2014).
Speaker information
Robert Hahn, University of Erlangen, Department of Material Science and Engineering, Institute for Surface Science and Corrosion (LKO) . In 2005 Robert Hahn joined the group of Prof. Schmuki at the Chair of Surface Science and Corrosion, Department of Material Science and Engineering of the Friedrich - Alexander University Erlangen – Nuremberg (Germany), where he worked as research assistant until 2009. In 2009, he was selected as senior scientist and was affiliated as researcher to the Cluster of Excellence - Engineering of Advanced Materials of the University. His main research activities are in the area of material science, semiconductor-electrochemistry and photochemistry and are centered on solar light to electric energy conversion and photo-catalysis. Special interest exists on the anodic growth of nanostructured materials (mainly self-organized metal oxide nanotubes), the modification of optical, electronic and mechanical properties of semiconductors using high temperature treatments and the development of nanostructured electrodes with advanced functionality for electrochemically based applications.