AVS 59th Annual International Symposium and Exhibition
    Surface Science Tuesday Sessions
       Session SS-TuM

Paper SS-TuM5
Reactivity of Highly-hydroxylated TiO2(110) Surface Prepared via Carboxylic Acid Adsorption and Photolysis

Tuesday, October 30, 2012, 9:20 am, Room 21

Session: Surface Reactivity of Oxides
Presenter: I. Lyubinetsky, Pacific Northwest National Laboratory
Authors: I. Lyubinetsky, Pacific Northwest National Laboratory
Y.G. Du, Pacific Northwest National Laboratory
N.G. Petrik, Pacific Northwest National Laboratory
N.A. Deskins, Worcester Polytechnic Institute
Z.-T. Wang, Pacific Northwest National Laboratory
M.A. Henderson, Pacific Northwest National Laboratory
G.A. Kimmel, Pacific Northwest National Laboratory
Correspondent: Click to Email
We present a novel, photochemical approach to prepare a highly-hydroxylated TiO2(110) and discuss the reactivity of the resulting surface. TiO2(110) surfaces with an OHb coverages up to 0.5 ML have been obtained upon trimethyl acetic acid (TMAA) dissociative adsorption and subsequent photolysis at 300 K. The formation and chemistry of such surface have been examined at the atomic level by a combination of scanning tunneling microscopy, temperature-programmed desorption, photo stimulated desorption, and density functional theory methods. Deprotonation of TMAA molecules upon adsorption produces both surface bridging hydroxyls (OHb) and bidentate trimethyl acetate (TMA) species with saturation coverage of near 0.5 ML. The TMA species can be selectively removed by ultra-violet light irradiation while OHb’s survive photolysis. At high coverages, the OHb species typically occupy second-nearest neighbor sites along the bridging oxygen row locally forming linear (2´1) structures of different lengths, although the surface is less ordered on a long scale. The annealing of the highly-hydroxylated surface leads to hydroxyl recombination and H2O desorption with ~100% yield, thus ruling out the diffusion of H into the bulk. In agreement with experimental data, theoretical results show that the recombinative H2O desorption is preferred over both H bulk diffusion and H2 desorption processes.