A new form of chemisorbed photo- and electro-active atomic H species on the TiO2(110) surface

Hydrogen adsorption on TiO2 is of importance in chemical and photochemical reduction processes. Using several surface science methods, we clearly distinguish two kinds of H species on the surface of rutile TiO2(110)-1 x 1. In contrast with the well-studied bridge-bonded OH species (alpha-H) originating from H2O dissociation on the surface oxygen vacancy site on TiO2(110), atomic H adsorption on the TiO2(110) (denoted as beta-H) exhibits special high sensitivity to the electronic excitation of the TiO2(110) by either electrons or UV photons. The formation of molecular H-2 gas by photoexcitation of beta-H/TiO2(110) surfaces has been observed, which may shed light on the basic understanding of the processes of photocatalytic H-2 production by splitting water. (C) 2016 Elsevier B.V. All rights reserved.