Activation of water on the TiO2 (110) surface: the case of Ti adatoms.

Using first-principles calculations we have studied the reactions of water over Ti adatoms on the (110) surface of rutile TiO(2). Our results provide fundamental insights into the microscopic mechanisms that drive this reaction at the atomic level and assess the possibility of using this system to activate the water dissociation reaction. In particular, we show that a single water molecule dissociates exothermically with a small energy barrier of 0.17 eV. After dissociation, both H(+) and OH(-) ions bind strongly to the Ti adatom, which serves as an effective reactive center on the TiO(2) surface. Finally, clustering of Ti adatoms does not improve the redox activity of the system and results in a slightly higher energy barrier for water dissociation.