Cohesive‐Energy‐Resolved Bandgap of Nanoscale Graphene Derivatives

Abstract

With a size-dependent cohesive energy formula for two-dimensional coordinated materials, the bandgap variation in quantum dots and nanoribbons of graphene derivatives, such as graphane, fluorographene and graphene oxides, is investigated. The bandgap is found to increase substantially as the diameter or width of the nano-sized material decreases. The bandgap variation is attributed to the change in cohesive energy of edge carbon atoms, and is associated with the physicochemical nature and degree of edge saturation. These predictions agree with previously reported computer simulation results, and have potential application in wide-band optics and optoelectronics.

Density functional theory study of B‐ and Si‐doped carbons and their adsorption interactions with sulfur compounds

“…Table 1 lists the total energy ( E tot ), cohesive energy ( E coh ), energy gap ( E g ), and Fermi level ( E f ) for each system. Larger values of the total energy and E coh indicate a more stable system 58 . The formula for calculating the cohesive energy is as follows 40 : $$${E}_{\mathrm{coh}}=[{E}_{\mathrm{tot}}-n{E}_{{\rm{c}}}-m{E}_{\mathrm{dop}}]/(n+m),$$$where E tot is the total energy of the system, eV; E c is the energy of a free state C atom, eV; E dop is the energy of a free state dopant atom, eV; n and m are the number of C and dopant atoms in the doped system, respectively.…”

“…Larger values of the total energy and E coh indicate a more stable system. 58 The formula for calculating the cohesive energy is as follows 40 :…”