Termodinámica y defectos de los bordes doblados engrafeno

Abstract

Abstract: Topological Stone-Wales (SW) defects can significantly affect the chemical, mechanical and electronic properties of graphene and similar carbon frameworks. Yet, thermodynamics and kinetics of SW defects in these nanomaterials are not fully understood. Here, we report the formation energies of SW defects in graphene, carbon nanotubes (CNTs), and folded graphene, using computer simulations based on density functional tight-binding (DFTB) and interatomic potential methods, supported by density functional theory (DFT) modelling where possible. According to our DFTB simulations, the formation energy of the SW defects in graphene is 5.11 eV which compares very well to that predicted by DFT, 4.96 eV. These values, however, are likely to be affected by the size of the slab used in the simulations, so an analytical expression was developed to calculate the formation energy for an isolated SW defect on graphene, which was estimated as 4.77 eV using DFTB data. Our DFTB results also indicates that the formation energy of SW defects on CTNs is strongly dependant on the structural properties of the tubes and the orientation of the defect. Finally, interatomic potential calculations predict that SW defects at the folded edges of folded graphene are more stable than at the graphite by up to 3.4 eV for one-fold and up to 1.4 for two-folds, which indicates that these defects tend to segregate in the arched structures in folded graphene.