Ordered '3D-superlattice' oxide nanotubes with highly defined physical and selective chemical contrasts
Final Report Abstract
A large amount of research work has been carried out in the frame of the project in the fields of creation of superlattice based on multilyer thin film anodization, tailoring the functional properties of advanced oxide nanostructures, creation of novel functional oxide nanoarchitectures by anodization, and elucidation of mechanisms of self-organizing electrochemical oxidation. The enhanced understanding on the controlling mechanisms of nanotube growth, on one hand side enabled to achieve novel highly promising functional surface layers on metals and alloys, but in addition led to a theoretical model on the driving force for self-organize pore/tube formation during oxide growth. Self-organizing anodization regimes were developed not only for Ti-X alloys (leading to in situ doping due to mixed oxide formation), but also for a range of other metals where promising functional oxide formation was expected (such as V2O5 on V). The combination of both materials and the nanotubular/nanoporous geometry was shown to be very promising in various functional applications, such as: TiO2 based solar cells (dye-sensitized solar cells, DSSCs): Key factors influencing the efficiency were determined, such as altered electric conductivity, junction formation, as well as control of the geometry and morphology of the tube walls. - Photocatalysis: Increase of the photocatalytic efficiency of TiO2 based nanotubes was achieved by doping or band gap engineering, co-catalyst decoration, or junction formation. - Noble-metal free solar-driven photocatalysts for H2 production from water were detected. - Electrochromic devices, batteries, smart windows: Ion (H+, or Li+)- insertion devices were shown to benefit from higher switching kinetics, better cycling stability, better ion-storage performance of the novel materials and geometries. - Memristic devices: Novel TiO2 nanostructures were shown to show promising memristive effects.
Publications
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Enabling the anodic growth of highly ordered V2O5 nanoporous/nanotubular structures, Angewandte Chemie - International Edition 50 (2011) 9071-9075
Yang, Y., Albu, S.P., Kim, D., Schmuki, P.
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Oxide nanotubes on Ti-Ru alloys: Strongly enhanced and stable photoelectrochemical activity for water splitting, Journal of the American Chemical Society 133 (2011) 5629-5631
Roy, P., Das, C., Lee, K., Hahn, R., Ruff, T., Moll, M., Schmuki, P.
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A review of photocatalysis using self-organized TiO2 nanotubes and other ordered oxide nanostructures, Small 8 (2012) 3073-3103
Paramasivam, I., Jha, H., Liu, N., Schmuki, P.
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Morphological instability leading to formation of porous anodic oxide films, Nature Materials 11 (2012) 162-166
Hebert, K.R., Albu, S.P., Paramasivam, I., Schmuki, P.
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Ultrafast growth of highly ordered anodic TiO2 nanotubes in lactic acid electrolytes, Journal of the American Chemical Society 134 (2012) 11316-11318
So, S., Lee, K., Schmuki, P.
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Intrinsic Au decoration of growing TiO2 nanotubes and formation of a high-efficiency photocatalyst for H2 production, Advanced Materials 25 (2013) 6133-6137
Lee, K., Hahn, R., Altomare, M., Selli, E., Schmuki, P.
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Transport properties of single TiO2 nanotubes, Applied Physics Letters 103 (2013) art. no. 173108
Stiller, M., Barzola-Quiquia, J., Lorite, I., Esquinazi, P., Kirchgeorg, R., Albu, S.P., Schmuki, P.
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Black TiO2 nanotubes: Cocatalyst-free open-circuit hydrogen generation, Nano Letters 14 (2014) 3309-3313
Liu, N., Schneider, C., Freitag, D., Hartmann, M., Venkatesan, U., Müller, J., Spiecker, E., Schmuki, P.
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Hierarchical DSSC structures based on "single walled" TiO2 nanotube arrays reach a back-side illumination solar light conversion efficiency of 8%, Energy and Environmental Science 8 (2015) 849-854
So, S., Hwang, I., Schmuki, P.
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Molten o –H3PO4 : A new electrolyte for the anodic synthesis of self-organized oxide structures – WO3 nanochannel layers and others, Journal of the American Chemical Society 137 (2015) 5646-5649
Altomare, M., Pfoch, O., Tighineanu, A., Kirchgeorg, R., Lee, K., Selli, E., Schmuki, P.
