▎ 摘　　要

High-precision thermodynamic data were derived for single-layer graphene growth on Cu by measuring an increase or decrease in graphene flake size during chemical vapor deposition (CVD) in a reactive CH4/H-2 atmosphere. An immediate flake shape change was observed when crossing the thermodynamic equilibrium of graphene formation, which was used as a sensitive criterion when systematically varying the CVD parameters during growth at 975-1080 degrees C. Extraction of the reaction enthalpy (Delta H-R degrees = 91.8 +/- 2.4 kJ.mol(-1)) and entropy (Delta S-R degrees = 108.0 +/- 1.8 J.mol(-1).K-1) provides the anchoring point highly needed for calibration of experimental reactor studies or theoretical work. Comparing the Gibbs free energy with the thermodynamic data of graphite formation verifies that self-limiting single-layer graphene growth on copper occurs purely kinetically. Thermodynamics always favors the formation of multilayer graphene. Identifying the CVD parameter space where multilayer graphene is formed while single-layer graphene decays will foster the development of future synthesis strategies. The gained knowledge is transferable to other CVD-based graphene growth systems.