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M. Setvin, U. Aschauer, J. Hulva, T. Simschitz, B. Daniel, M. Schmid, A. Selloni, U. Diebold:
"Following the Reduction of Oxygen on TiO₂ Anatase (101) Step by Step";
Journal of the American Chemical Society, 138 (2016), 9565 - 9571.

We have investigated the reaction between O2 and
H2O, coadsorbed 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.