Surface acidity and properties of tiO 2/SiO 2 catalysts prepared by atomic layer deposition: Uv-visible diffuse reflectance, dRIFTS, and visible raman spectroscopy studies

Junling Lu, Kathryn M. Kosuda, Richard P. Van Duyne, Peter C Stair

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

Highly uniform submonolayer to multilayer thin films of titanium dioxide supported on high surface area silica gel have been synthesized by atomic layer deposition (ALD) using titanium tetrachloride (TiCl4) and titanium isopropoxide (TTIP) as metal precursors. The deposition rate of titania films from TiCl4was found to be stable in the 150-300 °C temperature range, which is slightly higher than that from TTIP at 150 °C. UV-visible diffuse reflectance spectroscopy (DRS) shows that the coordination geometry of Ti cations depends on the number of ALD cycles and the precursor but is essentially independent of deposition temperature. Using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and visible Raman spectroscopy with pyridine as a probe molecule, we found all of the titania films studied to exhibit Lewis acidity but only films containing chloride or carbonyl impurities possessed Brønsted acid sites. Additionally, three new pronounced bands in the Raman spectra, v 6b(638 cm -1), v 9a(1200 cm -1), and v 2(3103 cm -1), provide strong spectroscopic evidence for Brønsted acid sites on the surface.

Original languageEnglish
Pages (from-to)12412-12418
Number of pages7
JournalJournal of Physical Chemistry C
Volume113
Issue number28
DOIs
Publication statusPublished - Jul 16 2009

Fingerprint

Atomic layer deposition
atomic layer epitaxy
Acidity
acidity
Raman spectroscopy
titanium
Titanium
reflectance
catalysts
Catalysts
Acids
Multilayer films
Silica Gel
Deposition rates
Cations
Raman scattering
Chlorides
tetrachlorides
Metals
acids

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

Surface acidity and properties of tiO 2/SiO 2 catalysts prepared by atomic layer deposition : Uv-visible diffuse reflectance, dRIFTS, and visible raman spectroscopy studies. / Lu, Junling; Kosuda, Kathryn M.; Van Duyne, Richard P.; Stair, Peter C.

In: Journal of Physical Chemistry C, Vol. 113, No. 28, 16.07.2009, p. 12412-12418.

Research output: Contribution to journalArticle

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