Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 117: Graphene II: Adsorption, Intercalation and Doping (joint session O/TT)

O 117.2: Talk

Friday, March 20, 2020, 10:45–11:00, GER 37

Graphene on liquid Cu, a multiscale model rationalizing mesoscale flake alignment — •Juan Santiago Cingolani, Karsten Reuter, and Mie Andersen — Chair of Theoretical Chemistry, Technical University of Munich, Germany

In recent years the use of liquid Cu as a catalyst during chemical vapor deposition (CVD) has emerged as a promising method for the continuous production of high-quality single layer graphene. The processes involved, such as carbon nucleation, defect healing, or flake alignment, remain largely unexplored or lack convincing atomic-scale rationalization. Of particular interest is the reported meso-scale interaction between growing flakes that leads to an ordering into 2D lattices.

To address the latter, we engage in a multiscale modeling study, hierarchically combining molecular dynamics (MD) simulations with continuum theory. Using a third-generation charge optimized many body potential (COMB3), the MD simulations reveal a strong interaction of graphene flakes with the liquid substrate, leading even to their partial immersion. On the basis of thus determined material parameters like surface energy, charge transfer or average flake height above the surface, we then set up a simple continuum model assuming the flakes to be spherically charged particles. Within an order of magnitude, this model rationalizes the experimental observation of a coalescence of the growing hexagonal flakes into a close-packed structure with well-defined inter-flake separation in terms of long-range capillary and electrostatic interactions.