Issue 9, 2012

Hydrogen reactivity on highly-hydroxylated TiO2(110) surfaces prepared viacarboxylic acid adsorption and photolysis

Abstract

Combined scanning tunneling microscopy, temperature programmed desorption, photo stimulated desorption, and density functional theory studies have probed the formation and reactivity of highly-hydroxylated rutile TiO2(110) surfaces, which were prepared via a novel, photochemical route using trimethyl acetic acid (TMAA) dissociative adsorption and subsequent photolysis at 300 K. Deprotonation of TMAA molecules upon adsorption produces both surface bridging hydroxyls (OHb) and bidentate trimethyl acetate (TMA) species with a saturation coverage of nearly 0.5 monolayers (ML). Ultra-violet light irradiation selectively removes TMA species, producing a highly-hydroxylated surface with up to ~0.5 ML OHb coverage. 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 that has been suggested in the literature. In agreement with experimental data, theoretical results show that the recombinative H2O desorption is preferred over both H bulk diffusion and H2 desorption processes.

Graphical abstract: Hydrogen reactivity on highly-hydroxylated TiO2(110) surfaces prepared via carboxylic acid adsorption and photolysis

Supplementary files

Article information

Article type
Paper
Submitted
05 Aug 2011
Accepted
28 Oct 2011
First published
22 Nov 2011

Phys. Chem. Chem. Phys., 2012,14, 3066-3074

Hydrogen reactivity on highly-hydroxylated TiO2(110) surfaces prepared via carboxylic acid adsorption and photolysis

Y. Du, N. G. Petrik, N. A. Deskins, Z. Wang, M. A. Henderson, G. A. Kimmel and I. Lyubinetsky, Phys. Chem. Chem. Phys., 2012, 14, 3066 DOI: 10.1039/C1CP22515D

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