Adsorption of Bi-Isonicotinic Acid on Rutile TiO2 (110)

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Bi-isonicotinic acid ~2,28-bipyridine–4,48-dicarboxylic acid! is the ligand of several organometallic
dyes, used in photoelectrochemical applications. Therefore the atomic scale understanding of the
bonding of this molecule to rutile TiO2(110) should give insight into the crucial dye–surface
interaction. High resolution x-ray photoelectron spectroscopy ~XPS!, near edge x-ray absorption
fine structure ~NEXAFS!, and periodic intermediate neglect of differential overlap ~INDO!
calculations were carried out on submonolayer bi-isonicotinic acid rutile TiO2(110). Data from
multilayers is also presented to support the submonolayer results. For a multilayer, XPS shows that
the carboxyl groups remain in the ~pristine! protonated form, and NEXAFS show that the molecular
plane is tilted by 57° with respect to the surface normal. For the submonolayer, the molecule bonds
to the rutile TiO2(110) surface via both deprotonated carboxyl groups, with a tilt angle of 25°, and
additionally an azimuthal orientation of 44° with respect to the @001# crystallographic direction. The
adsorbant system was also investigated by quantum mechanical calculations using a periodic INDO
model. The most stable theoretical adsorption geometry involves a twist around the molecular axis,
such that the pyridine rings are tilted in opposite directions. Both oxygen atoms of each carboxyl
group are bonded to five-fold coordinated Ti atoms ~2M-bidentate!, in excellent agreement with the
experimental results.


  • L. Patthey
  • H. Rensmo
  • Petter Persson
  • K. Westermark
  • L. Vayssieres
  • A. Stashans
  • A. Petersson
  • P. A. Bruhwiler
  • H. Siegbahn
  • S. Lunell
  • N. Mårtensson
Externa organisationer
  • External Organization - Unknown

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Atom- och molekylfysik och optik
Sidor (från-till)5913-5918
TidskriftJournal of Chemical Physics
StatusPublished - 1999
Peer review utfördJa
Externt publiceradJa