Molecular Precursor Induced Surface Reconstruction at Graphene/Pt(111) Interfaces
2015
Wang, Qian | Pang, Rui | Shi, Xingqiang
Inspired by experimental observations of Pt(111) surfaces reconstruction at the Pt/graphene (Gr) interfaces with ordered vacancy networks in the outermost Pt layer [e.g., Otero, G., et al. Phys. Rev. Lett. 2010, 105, 216102 ], the mechanism of the surface reconstruction is investigated by van der Waals corrected density functional theory in combination with particle-swarm optimization algorithm and ab initio atomistic thermodynamics. Our global structural search finds a more stable reconstructed structure than that which was reported before. With correction for vacancy formation energy, we demonstrate that the experimental observed surface reconstruction occurred at the earlier stages of graphene formation: (1) reconstruction occurred when C₆₀ adsorption (before decomposition to form graphene) for C₆₀ precursor or (2) reconstruction occurred when there were (partial) hydrogens remain in the hydrogenated precursors of C₂H₄ and planar C₆₀H₃₀. The reason is attributed to the fact that the energy gain, from the strengthened Pt–C partial sp³–like bonding for C of C₆₀ or for C with partial H (than Pt–Gr bonding), compensates for the energy cost of formation surface vacancies and makes the reconstruction feasible, especially at elevated temperatures. In our predicted reconstructed structure Pt–C covalent bonds are formed that have a great impact on the adsorbed Gr electronic structures.
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