AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThM

Paper SS1-ThM4
Density Functional Study of the Dissociative Adsorption of Formic Acid on the TiO@sub 2@ Rutile (0 1 1) Surface

Thursday, November 16, 2006, 9:00 am, Room 2002

Session: Reactivity of Oxide Surfaces I
Presenter: P.R. McGill, University of Auckland, New Zealand
Authors: P.R. McGill, University of Auckland, New Zealand
H. Idriss, University of Auckland, New Zealand
Correspondent: Click to Email
Titanium dioxide is used or present (as a consequence of oxidation of a titanium metal surface) in a range of applications, such as catalysts and medical implants, where its interaction with small adsorbed molecules is of considerable interest. While a number of studies have been conducted in this area, the majority of these have focused on the rutile (1 1 0) surface. The rutile (0 1 1) surface and its interaction with adsorbed species, while being the subject of a number of practical investigations, has until recently been neglected by computational studies. LEED evidence@footnote 1@ suggests that the (0 1 1) surface undergoes a 2x1 reconstruction as opposed to being bulk-terminated. Recently, a computational study@footnote 2@ has proposed a model for this 2x1 surface, and shows it to have several unique features such as Ti=O double bonds. In this work, periodic density functional calculations employing the PBE exchange-correlation functional and plane wave basis sets,@footnote 3@ are carried out on the adsorption of formic acid to the bulk-terminated and 2x1 models of the TiO@sub 2@ (0 1 1) surface. The 2x1 model is found to be more reactive, producing larger adsorption energies. A variety of interactions are possible for formic acid. Dissociative modes are considered because of the many experimental results which show their stable presence at room temperature. The acidic proton is thus assumed to transfer to a surface oxygen, while the remaining formate species interacts through its oxygens with one surface titanium in a monodentate or chelating fashion, or two surface titaniums in a bridging fashion. Stable conformations are found for the bridging and monodentate configurations. @FootnoteText@ @footnote 1@L. E. Firment, Surf.Sci. 116, 205 (1982)@footnote 2@T.J. Beck, A. Klust, M. Batzill, U. Diebold, C. Valentin, A. Selloni, Phys.Rev. Lett. 93, 036104 (2004)@footnote 3@Calculations performed using PWSCF, by S. Baroni, S. de Gironcoli, A. dal Corso, P. Giannozzi.