Bay-capping reactions: Kinetics and influence on graphene-edge growth

A capping reaction was found in a recent study to cause curvature in graphene edges and affect their growth rates. This reaction is initiated by acetylene addition to an armchair-like graphene radical site containing an embedded five-member ring. In this work, a combination of quantum-chemical calculations and reaction rate analysis was employed to explore the elementary steps of bay-capping reactions and to derive their rate coefficients. To evaluate the influence of the embedded five-member ring on six-member ring cyclization, the energetics and reaction rates of capping an embedded five-member ring were compared with those of capping a graphene armchair site. Detailed kinetic Monte Carlo simulations were performed to model evolution of graphene edges at conditions typical of soot growth and to examine the influence of the newly-derived rate coefficients.