Epitaxial Growth and Confinement of Graphene-Skinned Cu Powders: A Comprehensive Assessment of Crystallization Thermodynamics and Kinetics on Spherical Surfaces.

As a promising member of the graphene-skinned Cu powder family, this material integrates the properties of graphene with the inherent advantages of Cu. However, controlled growth on curved surfaces remains challenging due to curvature-induced stress, catalytic heterogeneity of molten Cu, and limited carbon migration. Using DFT, AIMD, LS-DYNA, and experimental verification, we show that curvature introduces a size-dependent energy barrier (181.87 eV for 10 nm vs. 21.40 eV for 10 µm) and elastic instability, triggering six-branched domains when the branch length exceeds a critical value lc = 0.0092R (where R is the powder radius). Surface premelting lowers the CH4 decomposition barrier to 1.10 eV, boosting carbon supply by 103-fold, yet simultaneously suppresses carbon surface diffusion by 104 times. Consequently, powders ≤10 µm exhibit ultrahigh nucleation density (up to 7.27 × 105 N/mm2) and low growth rates (0.92-3.64 µm/min). These effects intensify with decreasing particle size, whereas powders ≥50 µm behave similarly to flat foils. This work clarifies the synergy between curvature-induced elastic instability and premelting-mediated kinetics, identifies suitable Cu powder sizes for CVD graphene growth, and provides a theoretical foundation for optimizing CVD parameters (e.g., temperature and carbon flux) to obtain high-quality graphene coatings for high-performance composites.