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Chemical Characterization of Arrays of TiO2 Nanocolumns


EMSL Project ID
17490

Abstract

We propose to study thin nano-structured films of titanium oxide, and vanadium- and nitrogen-doped titanium oxide which we will deposit by employing reactive ballistic deposition (RBD). Properly performed, this process will yield films consisting of nanoporous, nanocolumns with tunable properties. The physical structure, atomic composition, and chemical binding and reactivity of the films will be characterized using in situ techniques such as thermal desorption spectroscopy (TDS), Auger electron spectroscopy (AES), and x-ray photoelectron spectroscopy (XPS), as well as electron microscopy (SEM and TEM), and x-ray diffraction (XRD). Additionally, the reactivity of RBD films (bare TiO2 films and doped films) can be compared with that of oxidized and partially reduced TiO2 single crystals using simple probe molecules such as H2O, CO, CH3OH, NOx, and CH4. Adsorption and chemistry of these molecules on TiO2 single crystal systems have been extensively studied by investigators and will serve as a benchmark for determining unique properties of the systems which arise due to film structure and doping.
Dohnalek et al. [4,5] and Brett and co-workers [1-3] have investigated how the micro-structure of the films, column angle and inter-column separation, depend on the deposition angle and annealing conditions. However, study of RBD systems is incomplete as the literature reveals only two investigations of gas physisorption [4,5] whereas no publications exist addressing the chemical and reactive nature of these films. Therefore we propose to; (i) grow RBD films and investigate effects of deposition and annealing conditions on the structure of the films, (ii) conduct TDS and reactive scattering studies utilizing simple, physisorbed probe molecules, possibly N2 at PNNL, (iii) perform TDS experiments involving dissociative and recombinative chemisorption processes on the RBD films. By completing this series of measurements we will make significant progress towards understanding effects of the RBD structure on adsorption processes and chemical reactivity.

Project Details

Project type
Exploratory Research
Start Date
2006-01-16
End Date
2007-02-05
Status
Closed

Team

Principal Investigator

David Flaherty
Institution
University of Texas at Austin

Team Members

C. Buddie Mullins
Institution
University of Texas at Austin

Zdenek Dohnalek
Institution
Pacific Northwest National Laboratory

Bruce Arey
Institution
Pacific Northwest National Laboratory

Related Publications

D. W. Flaherty, Z. Dohnalek, A. Dohnalkova, B. W. Arey, D. E. McCready, N. Ponnusamy, C. B. Mullins, B. D. Kay, "Reactive Ballistic Deposition of Porous TiO2 Films: Growth and Characterization," J. Phys. Chem. C 2007, 111, 4765-4773