Data di Pubblicazione:
2010
Abstract:
A study was carried out on the consequences of the -OHsurf/F- exchange occurring at the surface of TiO2 P25 when
suspended in HF/F- solutions. The maximum extent of fluorination was reached at pH 3.0, resulting in the fixation on
the surface of ca. 2.5 F-/nm2. The surface features of fluorinated samples under two selected conditions were
investigated by IR spectroscopy, in comparison with pristine TiO2. The collected data suggested that bridged -OHsurf,
likely located on regular facets, was more resistant to exchange with F-. Combined high resolution transmission electron
microscopy (HRTEM), inductively coupled plasma mass spectrometry (ICP-MS) and IR measurements indicated that
the fluorination performed in the adopted condition did not induce any etching of TiO2 particles, and the -OHsurf/F-
exchange appeared reversible by treatment in concentrated basic solutions. Furthermore, fluorination resulted in an
increase of the Lewis acid strength of surface Ti4þ sites, which, as a consequence, retained adsorbed water molecules even
after outgassing at 423 K. Such an effect involved the overwhelming majority of cations exposed on regular facets.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
titania; surface fluorination; IR
Elenco autori:
M. Minella; M.G. Faga; V. Maurino; C. Minero; E. Pelizzetti; S. Coluccia; G. Martra
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