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Title: Level Alignment of a Prototypical Photocatalytic System: Methanol on TiO2(110)

Photocatalytic activity depends on the optimal alignment of electronic levels at the molecule₋ semiconductor interface. Establishing the level alignment experimentally is complicated by the uncertain chemical identity of the surface species. We address the assignment of the occupied and empty electronic levels for the prototypical photocatalytic system consisting of methanol on a rutile TiO2(110) surface. Using many-body quasiparticle (QP) techniques, we show that the frontier levels measured in UV photoelectron and two-photon photoemission spectroscopy experiments can be assigned to molecularly chemisorbed methanol rather than its dissociated product, the methoxy species. We find that the highest occupied molecular orbital of the methoxy species is much closer to the valence band maximum, suggesting why it is more photocatalytically active than the methanol molecule. Finally, we develop a general semiquantitative model for predicting many-body QP energies based on the electronic screening within the bulk, molecular, or vacuum regions of the wave functions at molecule₋semiconductor interfaces.
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Univ. del Pais Vasco UPV/EHU, San Sebastian (Spain); Consejo Superior de Investigaciones Cientificas (CSIC), Barcelona (Spain)
  2. Univ. del Pais Vasco UPV/EHU, San Sebastian (Spain)
  3. Univ. of Science and Technology of China, Hefei (China)
  4. Univ. of Pittsburgh, PA (United States)
Publication Date:
OSTI Identifier:
DOE Contract Number:
AC05-76RL01830; CHE-1213189
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the American Chemical Society; Journal Volume: 135; Journal Issue: 31
American Chemical Society (ACS)
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
Country of Publication:
United States
Environmental Molecular Sciences Laboratory