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TT: Fachverband Tiefe Temperaturen

TT 72: Graphene II: Adsorption, Intercalation and Doping (joint session O/TT)

TT 72.1: Vortrag

Freitag, 20. März 2020, 10:30–10:45, GER 37

Ab initio thermodynamics of hydrocarbons relevant to graphene growth at solid and liquid Cu surfaces — •Mie Andersen, Juan Santiago Cingolani, and Karsten Reuter — Theoretical Chemistry, Technische Universität München, Germany

High quality graphene can be synthesized through chemical vapor deposition (CVD) at liquid Cu [1]. However, the role of the liquid catalyst surface is not yet well understood, and the role of hydrogen in the reactant mixture is still debated [2]. Here [3], we use ab initio thermodynamics to study the stability of a wide range of hydrocarbons under various CVD conditions (temperature, methane and hydrogen pressures) used in experimental growth protocols at solid and liquid Cu surfaces. We compare various low-index Cu facets and make use of hindered translator/rotator or ideal 2D gas models [4] to describe the adsorbate free energies. We find that smaller hydrocarbons will completely dehydrogenate under most CVD conditions. For larger graphene-like clusters, metal-terminated and hydrogen-terminated edges have very similar stabilities. While both cluster types might thus form during the experiment, we show that the low binding strength of clusters with hydrogen-terminated edges could result in instability towards desorption.

[1] D. Geng et al., PNAS 109, 7992 (2012)

[2] X. Zhang et al., JACS 136, 3040 (2014)

[3] M. Andersen, J.S. Cingolani, K. Reuter, J. Phys. Chem. C 123, 22299 (2019)

[4] L.H. Sprowl et al., J. Phys. Chem. C 120, 9719 (2016)