Isomerization of sp2-hybridized carbon nanomaterials: structural transformation and topological defects of fullerene, carbon nanotube, and graphene

The structural transformation of various carbon nanomaterials, such as fullerene, carbon nanotube (CNT), and graphene, has been extensively studied both experimentally and theoretically. It was broadly recognized that the isomerization of the sp2-hybridized carbon network through the generalized Stone-Wales transformation (GSWT), which is equivalent to a C C bond's in-plane rotation, is the key mechanism facilitating most structural revolutions in carbon materials. The GSWT process also plays a crucial role in the shape change, defect healing and the growth in these carbon materials and may greatly affect their mechanical, chemical, and electronic performances. In this review, we summarize the previous studies on the GSWT and topological defects in the sp2 carbon network as well as the consequent results of sp2-hybridized carbon materials' isomerization, including structural shrinkage of the giant fullerenes and CNTs at high temperature, plastic deformation of CNTs, coalescence of the fullerenes and carbon peapods, topological defects evolution under high energetic irradiation, and healing of the defects during the chemical vapor deposition growth of CNT and graphene. This review provides a clear picture of the isomerization of the sp2hybridized carbon materials, from single step process until the large-scale structural transformation, and many examples for the readers to get into the topic deeply step by step. (C) 2016 John Wiley & Sons, Ltd