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Comparing quasiparticle H2O level alignment on anatase and rutile TiO2

By Huijuan Sun, Duncan J. Mowbray, Annapaola Migani, Jin Zhao, Hrvoje Petek and Angel Rubio

Abstract

arXiv:1506.04695v1Knowledge of the alignment of molecular frontier levels in the ground state can be used to predict the photocatalytic activity of an interface. The position of the adsorbate’s highest occupied molecular orbital (HOMO) levels relative to the substrate’s valence band maximum (VBM) in the interface describes the favorability of photogenerated hole transfer from the VBM to the adsorbed molecule. This is a key quantity for assessing and comparing H2O photooxidation activities on two prototypical photocatalytic TiO2 surfaces: anatase (A)-TiO2(101) and rutile (R)-TiO2(110). Using the projected density of states (DOS) from state-of-the-art quasiparticle (QP) G0W0 calculations, we assess the relative photocatalytic activity of intact and dissociated H2O on coordinately unsaturated (Ticus) sites of idealized stoichiometric A-TiO2(101)/R-TiO2(110) and bridging O vacancies (Obrvac) of defective A-TiO2–x(101)/R-TiO2–x(110) surfaces (x = 1/4, 1/8) for various coverages. Such a many-body treatment is necessary to correctly describe the anisotropic screening of electron–electron interactions at a photocatalytic interface and, hence, obtain accurate interfacial level alignments. The more favorable ground state HOMO level alignment for A-TiO2(101) may explain why the anatase polymorph shows higher photocatalytic activities than the rutile polymorph. Our results indicate that (1) hole trapping is more favored on A-TiO2(101) than R-TiO2(110) and (2) HO@Ticus is more photocatalytically active than intact H2O@Ticus.We acknowledge financial support from the China Scholarship Council (CSC), the European Projects DYNamo (ERC-2010-AdG-267374), CRONOS (280879-2 CRONOS CP-FP7), Cost Actions CM1204 (XLIC), and MP1306 (EuSpec); Spanish Grants (FIS2012-37549-C05-02, FIS2013-46159-C3-1-P, PIB2010US-00652, RYC-2011-09582, JCI-2010-08156); Generalitat de Catalunya (2014SGR301, XRQTC); Grupos Consolidados UPV/EHU del Gobierno Vasco (IT-578-13); NSFC (21003113 and 21121003); MOST (2011CB921404); the Chinese Academy of Sciences President’s International Fellowship; NSF Grant CHE-1213189; and computational time from the Shanghai Supercomputing Center, BSC Red Espanola de Supercomputacion, and EMSL at PNNL by the DOE.Peer Reviewe

Topics: Photooxidation, Photocatalysis, G0W0 calculations, Water splitting, Titania, Hole trapping
Publisher: 'American Chemical Society (ACS)'
Year: 2016
DOI identifier: 10.1021/acscatal.5b00529
OAI identifier: oai:digital.csic.es:10261/131626
Provided by: Digital.CSIC

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