Atomic-scale growth mechanism of graphene on micrometer-sized AlN powders with curvature effect analysis

Aluminum nitride (AlN) powders show great potential for high-efficiency thermal management due to their high thermal conductivity and excellent electrical insulation. However, their practical thermal performance is often limited by interfacial thermal resistance and surface instability. Growing graphene on AlN powder surfaces is expected to simultaneously enhance interfacial heat transport and provide surface protection. The growth mechanism of graphene on micrometer-sized AlN powders remains unclear, which limits experimental control of synthesis. In this work, density functional theory is used to systematically study the formation and growth of graphene on AlN surfaces. Curvature energy analysis first shows that surface curvature no longer dominates the early growth of graphene in micrometer-sized powder systems. Based on this, the key reaction pathways and kinetic features under different carbon precursors are further revealed. The results show that: (i) Carbon precursors decompose both on the substrate surface and in the gas phase, supplying carbon active species for growth; (ii) The dominant nucleation species depends on the precursor, with C dominating in the C₂H₂ system and CH₂C dominating in the C₂H₄ system; (iii) During edge growth, CHCH is the dominant active species in both systems. The growth barrier along the armchair (AC) edge is much lower than that along the zigzag (ZZ) edge. This indicates that graphene growth exhibits a pronounced edge dependence. This work provides a mechanism of graphene growth on micrometer-sized aluminum nitride powders, providing theoretical guidance for its controlled preparation.