Insights into the Coadsorption and Reactivity of O and CO on Ru(0001) and Their Coverage Dependence

Using density functional theory and an exchange–correlation that includes the van der Waals interaction, we study coadsorption of CO on Ru(0001) saturated with 0.5 ML oxygen. Different coexisting coverages are considered experimentally motivated, room temperature coverage consisting ML-O + 0.25 ML-CO (low coverage), saturation achieved at low temperatures (0.5 0.375 ML-CO, intermediate equally mixed monolayer is stable according to our calculations but not observed yet high coverage). For each coverage, competition between desorption oxidation corresponding optimized structure by analyzing their reaction energies minimum energy paths. The process endothermic all coverages, although decreases as increases. itself (and also reverted adsorption) becomes more involved because appearance a physisorption well concomitant barrier separating it from chemisorbed state. Remarkably, CO, which turns exothermic coverages. In cases, path for oxidation, involves physisorbed CO2, ruled one large barriers protect these molecular states. Altogether, larger activation compared those extreme complexity against paths explain dominates over in experiments.