Cyclotrimerization nucleation of dimeric carbon precursors for roll-to-roll synthesis of high-orientation graphene

Scalable synthesis of high-quality graphene via roll-to-roll chemical vapor deposition faces a fundamental conflict between rapid growth and crystallographic perfection. Conventional methane (CH₄)-derived growth suffers from disordered nucleation and orientation mismatch at elevated precursor pressures, limiting industrial adoption. This work resolves this challenge by employing acetylene (C₂H₂) as a carbon precursor to enable carbon dimer-mediated cyclotrimerization nucleation. First-principles calculations reveal that C₂H₂-derived carbon dimers (C₂) spontaneously assemble into hexagonal nuclei, bypassing defect-prone chain-to-ring transitions inherent to monatomic carbon pathway of CH₄. This mechanism ensures > 98% lattice orientation consistency even at nucleation densities of 10⁴ mm⁻², in stark contrast to CH₄-derived graphene. Crucially, the enhanced surface adsorption of C₂ species enables continuous nucleation during lateral growth, achieving high growth rate of 500 mm·min⁻¹ at roll-to-roll process. Leveraging dimeric carbon precursors and Cu single-crystallization technique, we demonstrate roll-to-roll production of graphene films with high crystallographic orientation across meter-scale Cu(111) foils. This precursor-specific strategy decouples nucleation density from disorder accumulation, establishing a scalable pathway for industrial graphene manufacturing.