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

Journal Article · Thu Jul 18 00:00:00 EDT 2013 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja4036994· OSTI ID:1097925

Migani, Annapaola ^[1]; Mowbray, Duncan J. ^[2]; Iacomino, Amilcare ^[2]; Zhao, Jin ^[3]; Petek, Hrvoje ^[4]; Rubio, Angel ^[2]

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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)

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.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830; CHE-1213189
• OSTI ID: 1097925
• Journal Information: Journal of the American Chemical Society, Vol. 135, Issue 31; ISSN 0002-7863
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory