Following the reduction of oxygen on TiO2 anatase (101) step by step

M. Setvin, U. Aschauer, J. Hulva, T. Simschitz, B. Daniel, M. Schmid, A. Selloni, U. Diebold

Institut für Angewandte Physik, TU Wien, 1040 Wien, Austria
Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
Department of Chemistry, Princeton University, Frick Laboratory, Princeton, NJ 08544, U. S. A.

J. Am. Chem. Soc. 138 (2016) 9565-9571

We have investigated the reaction between O2 and H2O, co-adsorbed on the (101) surface of a reduced TiO2 anatase single crystal by scanning tunneling microscopy, density functional theory, temperature programmed desorption and X-ray photoelectron spectroscopy. While water adsorbs molecularly on the anatase (101) surface, the reaction with O2 results in water dissociation and formation of terminal OH groups. We show that these terminal OHs are the final and stable reaction product on reduced anatase. We identify OOH as a metastable intermediate in the reaction. The water dissociation reaction runs as long as the surface can transfer enough electrons to the adsorbed species; the energy balance and activation barriers for the individual reaction steps are discussed, depending on the number of electrons available. Our results indicate that the presence of donor dopants can significantly reduce activation barriers for oxygen reduction on anatase.

Corresponding author: Martin Setvin (setvin at iap_tuwien_ac_at).

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