Electron Transport via Polaron Hopping in Bulk TiO2: a density functional theory characterization
Abstract
In this work we describe our use of Marcus theory to model the electron transfer process in TiO2. Electron transport is described by a polaron model, whereby a photoexcited electron is localized at a Ti4+ site and hops to an adjacent Ti4+ site. We obtained the relevant parameters in Marcus theory (namely the activation energy ΔG*, the reorganization energy λ, and the electronic coupling matrix elements Vab) for selected crystallographic directions in rutile and anatase, using periodic DFT+U and HartreeFock cluster calculations. The DFT+U method was necessary to correct for the ubiquitous electron selfinteraction problem? in DFT. Our results give nonadiabatic activation energies of similar magnitude in rutile and anatase, all near 0.3 eV. The electronic coupling matrix element, Vab, was determined to be largest for electron transfer parallel to the c direction in rutile, with a value of 0.20 eV, while the other directions investigated in both rutile and anatase gave Vab values near 0 eV. The results are indicative of adiabatic transfer (thermal hopping mechanism) in rutile and of diabatic transfer (tunneling mechanism) in anatase. This work was supported by the Office of Basic Energy Sciences of the Department of Energy, in part by the Chemical Sciences programmore »
 Authors:
 Publication Date:
 Research Org.:
 Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 917932
 Report Number(s):
 PNNLSA52342
Journal ID: ISSN 01631829; PRBMDO; 3564a; KC0302010; TRN: US0805189
 DOE Contract Number:
 AC0576RL01830
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physical Review. B, Condensed Matter and Materials Physics, 75(19):Art. No. 195212; Journal Volume: 75; Journal Issue: 19
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACTIVATION ENERGY; ELECTRONS; FUNCTIONALS; MATRIX ELEMENTS; POLARONS; RUTILE; TRANSPORT; TUNNELING; WAVE FUNCTIONS; TITANIUM OXIDES; electron transfer process in TiO2; Marcus theory; adiabatic transfer; diabatic transfer; Environmental Molecular Sciences Laboratory
Citation Formats
Deskins, N. Aaron, and Dupuis, Michel. Electron Transport via Polaron Hopping in Bulk TiO2: a density functional theory characterization. United States: N. p., 2007.
Web. doi:10.1103/PhysRevB.75.195212.
Deskins, N. Aaron, & Dupuis, Michel. Electron Transport via Polaron Hopping in Bulk TiO2: a density functional theory characterization. United States. doi:10.1103/PhysRevB.75.195212.
Deskins, N. Aaron, and Dupuis, Michel. Tue .
"Electron Transport via Polaron Hopping in Bulk TiO2: a density functional theory characterization". United States.
doi:10.1103/PhysRevB.75.195212.
@article{osti_917932,
title = {Electron Transport via Polaron Hopping in Bulk TiO2: a density functional theory characterization},
author = {Deskins, N. Aaron and Dupuis, Michel},
abstractNote = {In this work we describe our use of Marcus theory to model the electron transfer process in TiO2. Electron transport is described by a polaron model, whereby a photoexcited electron is localized at a Ti4+ site and hops to an adjacent Ti4+ site. We obtained the relevant parameters in Marcus theory (namely the activation energy ΔG*, the reorganization energy λ, and the electronic coupling matrix elements Vab) for selected crystallographic directions in rutile and anatase, using periodic DFT+U and HartreeFock cluster calculations. The DFT+U method was necessary to correct for the ubiquitous electron selfinteraction problem? in DFT. Our results give nonadiabatic activation energies of similar magnitude in rutile and anatase, all near 0.3 eV. The electronic coupling matrix element, Vab, was determined to be largest for electron transfer parallel to the c direction in rutile, with a value of 0.20 eV, while the other directions investigated in both rutile and anatase gave Vab values near 0 eV. The results are indicative of adiabatic transfer (thermal hopping mechanism) in rutile and of diabatic transfer (tunneling mechanism) in anatase. This work was supported by the Office of Basic Energy Sciences of the Department of Energy, in part by the Chemical Sciences program and in part by the Engineering and Geosciences Division. The Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.},
doi = {10.1103/PhysRevB.75.195212},
journal = {Physical Review. B, Condensed Matter and Materials Physics, 75(19):Art. No. 195212},
number = 19,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}

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