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Title: Slow Equilibration between Spectroscopically Distinct Trap States in Reduced TiO 2 Nanoparticles

Journal Article · · Journal of the American Chemical Society
DOI:https://doi.org/10.1021/jacs.6b12112· OSTI ID:1388133
ORCiD logo [1];  [1]; ORCiD logo [1];  [1]
  1. Yale Univ., New Haven, CT (United States). Dept. of Chemistry
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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.

Research Organization:
Energy Frontier Research Centers (EFRC) (United States). Argonne-Northwestern Solar Energy Research Center (ANSER)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
SC0001059
OSTI ID:
1388133
Journal Information:
Journal of the American Chemical Society, Vol. 139, Issue 8; Related Information: ANSER partners with Northwestern University (lead); Argonne National Laboratory; University of Chicago; University of Illinois, Urbana-Champaign; Yale University; ISSN 0002-7863
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 23 works
Citation information provided by
Web of Science

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Cited By (5)

Proton-free electron-trapping feature of titanium dioxide nanoparticles without the characteristic blue color journal July 2019
Visible‐Light‐Driven Water Oxidation with a Polyoxometalate‐Complexed Hematite Core of 275 Iron Atoms journal April 2019
Cd/In-Codoped TiO 2 nanochips for high-efficiency photocatalytic dye degradation journal January 2018
Density functional theory study of atomic and electronic properties of defects in reduced anatase TiO 2 nanocrystals journal March 2018
Visible‐Light‐Driven Water Oxidation with a Polyoxometalate‐Complexed Hematite Core of 275 Iron Atoms journal May 2019

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
catalysis (homogeneous)
catalysis (heterogeneous)
solar (photovoltaic)
solar (fuels)
photosynthesis (natural and artificial)
bio-inspired
hydrogen and fuel cells
electrodes - solar
defects
charge transport
spin dynamics
membrane
materials and chemistry by design
optics
synthesis (novel materials)
synthesis (self-assembly)