Giant fullerene formation through thermal treatment of fullerene soot

Coalescence of fullerenes into giant fullerenes (C-n n > 100) has been observed in the gas phase and inside carbon nanotubes. In this work, we demonstrate the formation of giant fullerenes by heating fullerene soot. Extracting the majority of the magic number fullerenes (C-60 and C-70) allowed the underlying distribution of fullerenes in the solid state to be measured. Upon heating at 800-1000 degrees C for 30-60 min under vacuum the mass distribution of fullerenes was found to shift toward larger masses. High resolution electron microscopy was used to compare formation of giant fullerenes by thermal heating and electron beam irradiation, showing the former produced more isolated giant fullerene fragments >1 nm in size. The driving force for coalescence and growth by thermal heating was suggested to be vertex strain at pentagonal sites, providing a route towards the synthesis of fullerenes up to C-300. (C) 2017 Elsevier Ltd. All rights reserved.