Complex interaction of hydrogen with the RuO2(110) surface

Using a variety of dedicated surface sensitive techniques, we studied the interaction of hydrogen with bare and adsorbate modified RuO2(110) surfaces on the atomic scale. Hydrogen interacts strongly with the undercoordinated O atoms, thereby forming hydroxyl groups and passivating available oxygen species on the oxide surface, for instance, for the catalytic CO oxidation reaction. Temperature programmed reaction and desorption elucidate the complex reaction behavior of hydrogen with O precovered RuO2(110), including the hydrogen transfer reaction between the different kinds of undercoordinated surface oxygen atoms. Hydroxyl, water species, and hydrogen transfer are identified with high-resolution O1s core level spectroscopy by comparison with density functional theory (DFT) calculated O1s core level shifts. DFT calculations provide adsorption energies, atomic geometries, as well as diffusion barriers of H atoms on the RuO2(110) surface.