Simulations on the effects of confinement and Ni-catalysis on the formation of tubular fullerene structures from peapod precursors

We applied the recently developed reactive force field (ReaxFF) to study the dynamics of tubular fullerene formation process starting from ${\mathrm{C}}_{60}$-buckyball/nanotube peapod structures. We found that the space confinement provided by the single-wall nanotube encapsulating the buckyballs is of critical importance to this coalescence reaction. We also simulated the effects of Ni particles on the coalescence process and found a significant reduction of the reaction initiation temperature in the presence of these catalysts. One important quantity is the energy barrier of forming a 4-membered ring between adjacent buckyballs. This barrier is lowered by 40% with the aid of Ni-catalysis. This research can help the community to gain a better understanding of the complicated growth processes in fullerene systems.

Figure 1

(Color online) Peapod structure model of five buckyballs inside (10,10) SWCN.

Figure 2

Snapshots of ReaxFF dynamic simulations of five ${\mathrm{C}}_{60}$ balls coalescing inside a (10, 10) nanotube (diameter approximately $1.38\mathrm{nm}$) at $2500\mathrm{K}$ without catalysis. The SWCN is not shown here for clarity.

Figure 3

(Color online) Computed reaction barriers, using quantum mechanics and ReaxFF, of $(2+2)$ cycloaddition reaction between two ${\mathrm{C}}_{60}$ molecules with and without catalyst (Ni).

Figure 4

(Color online) Snapshots of ReaxFF dynamic simulations of five ${\mathrm{C}}_{60}$ balls coalescing inside a (10, 10) nanotube (diameter approximately $1.38\mathrm{nm}$) at $1800\mathrm{K}$ with two Ni atoms between each ${\mathrm{C}}_{60}$ pair. The SWCN is not shown here for clarity.