Imaging hindered rotations of alkoxy species on TiO2(110)

Zhenrong Zhang, Roger Rousseau, Jinlong Gong, Bruce D. Kay, Zdenek Dohnálek

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

We present the first scanning tunneling microscopy (STM) study of the rotational dynamics of organic species on any oxide surface. Specifically, variable-temperature STM and dispersion-corrected density functional theory (DFT-D) are used to study the alkyl chain conformational disorder and dynamics of 1-, 2-, 3- and 4-octoxy on rutile TiO2(110). Initially, the geminate pairs of the octoxy and bridging hydroxyl species are created via octanol dissociation on bridging-oxygen (Ob) vacancy defects. The STM images provide time-averaged snapshots of octoxy species rotating among multiple energetically nearly degenerate configurations accessible at a given temperature. In the calculations we find that the underlying corrugated potential energy surface is a result of the interplay between attractive van der Waals dispersion forces, leading to weak attractive C• • • Ti and repulsive C• • •Ob interactions which lead to large barriers of 50-70 kJ mol-1 for the rotation of the octoxy alkyl chains across the Ob rows. In the presence of the geminate hydroxyl groups we find that the relative populations of the various conformations as well as the rotational barriers are perturbed by the presence of geminate hydroxyl due to additional C• • • hydroxyl repulsions.

Original languageEnglish
Pages (from-to)17926-17932
Number of pages7
JournalJournal of the American Chemical Society
Volume131
Issue number49
DOIs
Publication statusPublished - Dec 16 2009

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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