First-principles based thermodynamics calculations predict that, depending on the operation conditions, CO adsorption, sintering of Ru species and disintegration of multinuclear surface Ru carbonyls into atomically dispersed Ru species are potential evolution pathways for graphene supported Ru clusters in CO atmosphere.
We investigated the evolution of Ru clusters containing 1–4 atoms supported on graphene in CO atmosphere with extensive first principle-based calculations. Exothermic CO adsorption induces gradual structure reorganization and change of the Ru−Ru, Ru-graphene, and Ru-CO interactions within these Ru carbonyls. The upper limits of CO on a surface of Ru cluster are 3, 6, 10 and 12 for Ru1, Ru2, Ru3 and Ru4, respectively. The further CO adsorption enhances steric hindrance at the Ru-graphene interface that finally leads to release of undercoordinated Ru carbonyls into gas phase. Competing with the CO adsorption and sintering of Ru species for better thermostability, disintegration of multinuclear surface Ru carbonyls to atomically dispersed Ru species on graphene is still feasible. The current findings bring more insights into the evolution and interconversion of Ru carbonyls in a CO atmosphere and may help to understand the superior performance of heterogeneous transition metal catalysts in operation conditions.Zum Volltext