Electrochemical Properties of Pt-Graphene Hybrid System: DFT Modeling Approach

Epitaxially grown Pt thin film on a graphene template is found to have a few monolayer thickness with structural stability comparable to Pt(111) surface and promising electrochemical activity. The newly synthesized thin film shows the crystalline Pt structure of quadrilateral polygon in mono-layer stacking, and simple cubic-like (SC-L) stacking in bi-layer film. In this study, we present a computational research on the unique architecture of the graphene templated epitaxial platinum layers in support of the remarkable recent progress. Recently proposed strongly constrained and appropriately normed (SCAN) density function study (DFT) is employed to investigate the materials characteristics. Electrochemical activities of the system are evaluated in terms of the free energy variation in oxygen reduction reaction (ORR). In architectures, Pt exhibits registry with the C-C bridge sites along the armchair and zigzag directions forming strong covalent bonds. Here, the details of the atomistic/electronic structures and binding energies are discussed. Interestingly, the ORR can occur on both Pt and graphene surfaces. This would provide a good strategy for 1) the protection of metallic catalyst and 2) tune the electronic structure of catalyst.