Several recent studies have addressed the importance of understanding confinement effects on reactivity. In the early 90's, Corma et al. had already described the phenomena in a series of studies associated with their observations of reactivity in zeolites. Other work focuses on reactions inside carbon nanotube systems, where it is claimed that due to the curvature effect there is an electronic redistribution of the π electron density of the graphene layers. Both in zeolites and inside carbon nanotubes, the electronic density of the atoms constituting the "caged" environment and those of the reactants, intermediates and products, may experience significant changes which make their chemical behavior to differ from bulk. In previous work, the reactivity of transition metal surfaces toward the dissociation reaction of diatomic molecules was found to increase when the dissociations take place in a confined space defined by two interacting metal surfaces separated by distances smaller than 5 A. The proximity of the metal surfaces at these small distances has been found to result in the presence of electrons in the gap between the surfaces. In this work we investigate reactivity in confined systems defined by metal/metal and nanosize metal/graphene systems. We also determine reactivity effects due to the interactions of Pt nanoclusters with graphite slabs, where the reactivity is tested using CO as a probe, and the electronic and chemical effects arising in the confined space between Pt clusters deposited on nanopillared graphene.
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