Environmental Effects On Reactivity at the RuO2(110) Surface

A key challenge in atomistic simulation of heterogeneous catalysis is to capture the effects of reaction environment on surface reactivity. The energetics, mechanisms, and even chemical species present at a reacting surface can be a strong function of the conditions to which the surface is exposed. In this work, we use DFT calculations and thermodynamic and kinetic modeling to examine two examples of such effects at the RuO2(110) surface. We first consider O2 adsorption and dissociation, and show that the molecular O2 species observed in TPD experiments and identified as a precursor to O2 dissociation is in fact a spectator present only at high coverages of surface O. The existence of “stranded” adsorption sites along the one-dimensional surface rows is shown to produce these stranded sites. We next consider catalytic CO oxidation and its competition with surface poisoning. We identify both carbonate and bicarbonate surface poisons and show that the coverage of the latter is highly sensitive to water concentration and likely accounts for the surface poisoning observed experimentally.