Ultrafast proton-coupled electron transfer in heterogeneous photocatalysis

Jin Zhao, Ken Onda, Bin Li, Hrvoje Petek

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

At metal-oxide/protic-solvent interfaces, partially hydrated or "wet electron" states represent the lowest energy pathway for electron transfer. Here we study the photoinduced charge transfer at the H 2O/TiO 2(110) interface by means of time-resolved two-photon photoemission spectroscopy and electronic structure theory. At ∼1 monolayer coverage of H 2O on partially hydroxylated TiO 2 surfaces we find an unoccupied electronic state 2.4±0.1 eV above the Fermi level. Density functional theory shows this to be a two-dimensional "wet electron" state, which is distinct from hydrated electrons observed on water-covered metal surfaces. The decay of electrons from the wet electron state by the resonant charge transfer to the conduction band of TiO 2 occurs in ≤15 femtoseconds. Similar unoccupied electronic structure is observed for CH 3OH covered TiO 2(110) surfaces; however, the electron dynamics are considerably more complex. The wet electron state dynamics of CH 3OH/TiO 2 exhibit both energy and population decay. The excited state lifetime is strongly coverage dependent increasing to >100 fs range above 1 ML CH 3OH coverage. Significantly, a pronounced deuterium isotope effect (CH 3OD) indicates a strong correlation between the interfacial electron transfer and the motion of protons in the molecular overlayer.

Original languageEnglish
Title of host publicationPhysical Chemistry of Interfaces and Nanomaterials V
DOIs
Publication statusPublished - Nov 23 2006
Externally publishedYes
EventPhysical Chemistry of Interfaces and Nanomaterials V - San Diego, CA, United States
Duration: Aug 15 2006Aug 17 2006

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6325
ISSN (Print)0277-786X

Other

OtherPhysical Chemistry of Interfaces and Nanomaterials V
CountryUnited States
CitySan Diego, CA
Period8/15/068/17/06

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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