Slow Equilibration between Spectroscopically Distinct Trap States in Reduced TiO2 Nanoparticles

Jennifer L. Peper, David J. Vinyard, Gary W Brudvig, James M. Mayer

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Understanding the nature of charge carriers in nanoscale titanium dioxide is important for its use in solar energy conversion, photocatalysis, and other applications. UV-irradiation of aqueous, colloidal TiO2 nanoparticles in the presence of methanol gives highly reduced suspensions. Two distinct types of electron traps were observed and characterized by EPR and optical spectroscopies. The relative populations of the states depend on temperature, indicating a small energy difference, ΔH° = 3.0 ± 0.6 kcal/mol (130 ± 30 meV). Interconversion between the electron traps occurs slowly over the course of minutes to hours within the temperature range studied here, 0-50 °C. The slow time scale implies that interconversion involves changes in structure or stoichiometry, not just the movement of electrons. This occurrence of slow structural modification with changes in trap state occupancy is likely a general feature of reduced TiO2 systems at thermodynamic equilibria or photostationary states and should be considered in the design of TiO2-containing devices.

Original languageEnglish
Pages (from-to)2868-2871
Number of pages4
JournalJournal of the American Chemical Society
Volume139
Issue number8
DOIs
Publication statusPublished - Mar 1 2017

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Electron traps
Nanoparticles
Electrons
Photocatalysis
Charge carriers
Energy conversion
Stoichiometry
Solar Energy
Titanium dioxide
Solar energy
Paramagnetic resonance
Methanol
Suspensions
Temperature
Irradiation
Thermodynamics
Spectrum Analysis
Equipment and Supplies
Population
Optical spectroscopy

ASJC Scopus subject areas

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

Cite this

Slow Equilibration between Spectroscopically Distinct Trap States in Reduced TiO2 Nanoparticles. / Peper, Jennifer L.; Vinyard, David J.; Brudvig, Gary W; Mayer, James M.

In: Journal of the American Chemical Society, Vol. 139, No. 8, 01.03.2017, p. 2868-2871.

Research output: Contribution to journalArticle

Peper, Jennifer L. ; Vinyard, David J. ; Brudvig, Gary W ; Mayer, James M. / Slow Equilibration between Spectroscopically Distinct Trap States in Reduced TiO2 Nanoparticles. In: Journal of the American Chemical Society. 2017 ; Vol. 139, No. 8. pp. 2868-2871.
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