Contiguous and Atomically Thin Pt Film with Supra-Bulk Behavior Through Graphene-Imposed Epitaxy

The nature of the atomic configuration and the bonding within epitaxial Pt-graphene films is investigated. Graphene-templated monolayer/few-multilayers of Pt, synthesized as contiguous 2D films by room temperature electrochemical methods, is shown to exhibit a stable {100} structure in the 1-2 layer range. The fundamental question being investigated is whether surface Pt atoms rendered in these 2D architectures are as stable as those of their bulk Pt counterparts. Unsurprisingly, a single layer Pt on the graphene (Pt_1ML/GR) shows much larger Pt dissociation energy (-7.51 eV) than does an isolated Pt atom on graphene. However, the dissociation energy from Pt_1ML/GR is similar to that of bulk Pt(100), -7.77 eV, while in bi-layer Pt on the graphene (Pt_2ML/GR), this energy changes to -8.63 eV, surpassing its bulk counterpart. At Pt_2ML/GR, the dissociation energy also slightly surpasses that of bulk Pt(111). Bulk-like stability of atomically thin Pt-graphene results from a combination of interplanar Pt-C covalent bonding and inter/intraplanar metallic bonding. This unprecedented stability is also accompanied by a metal-like presence of electronic states at the Fermi level. Such atomically thin metal-graphene architectures can be a new stable platform for synthesizing 2D metallic films with various applications in catalysis, sensing, and electronics.