Hydrogen adsorption onRuO2(110): Density-functional calculations

The structural, vibrational, energetic, and electronic properties of hydrogen at the stoichiometric $\mathrm{Ru}{\mathrm{O}}_{2}(110)$ termination are studied using density-functional theory. The oxide surface is found to bind both molecular and dissociated ${\mathrm{H}}_{2}$. Apart from the most stable configuration in the form of hydroxyl groups (monohydrides) at the undercoordinated ${\mathrm{O}}^{\mathrm{br}}$ surface anions, we also identify a molecular state at the undercoordinated ${\mathrm{Ru}}^{\mathrm{cus}}$ atoms (dihydrogen) and a waterlike species (dihydride) at the ${\mathrm{O}}^{\mathrm{br}}$ sites. Hydrogen adsorption at ${\mathrm{O}}^{\mathrm{br}}$ sites increases the reactivity of the neighboring ${\mathrm{Ru}}^{\mathrm{cus}}$ sites, which are believed to play a key role in catalytic oxidation reactions.