SurfaceScience21 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 36: Poster Session III: Electronic structure of surfaces: Spectroscopy, surface states I
O 36.7: Poster
Dienstag, 2. März 2021, 10:30–12:30, P
Photoexcitation of Bulk Polarons in Rutile TiO2 — •Alex Tanner1,2, Bo Wen3, Yu Zhang1,2, Li-min Liu4, Helen Fielding1, Annabella Selloni3, and Geoff Thornton1,2 — 1Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom — 2London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom — 3Department of Chemistry, Princeton University, Princeton NJ 08540, United States — 4School of Physics, Beihang University, Beijing, 100083, China
In recent years there has been considerable interest in the physics of polarons at reduced TiO2 surfaces. This includes two photon photoemission spectroscopy (2PPE) studies, which have proposed that polaron excitation may represent an alternative vector to band gap excitation in photocatalysis. These studies show that surface-localized polarons in rutile TiO2(110) couple with excited electronic states ca. 2.6 eV above the conduction band minimum. However, readily oxidised surface polarons likely have a minimal contribution in catalytic applications. In contrast, polarons in bulk TiO2 remain protected and therefore offer intriguing potential.
With 2PPE and hybrid density functional theory, we find bulk polarons are less bound by 0.2 eV compared with polarons at the surface. Because the excited state is also shifted to higher energy, bulk polarons have the same resonance energy as at the surface with a threshold at 3.1 eV. This is degenerate with the band gap, suggesting that bulk polarons could also provide an additional contribution to the photoyield.