Interaction of two symmetric monovacancy defects in graphene

We investigate the interactions between two symmetric monovacancy defects in graphene grown on Ru(0001) after silicon intercalation by combining first-principles calculations with scanning tunneling microscopy(STM). First-principles calculations based on free-standing graphene show that the interaction is weak and no scattering pattern is observed when the two vacancies are located in the same sublattice of graphene, no matter how close they are, except that they are next to each other. For the two vacancies in different sublattices of graphene, the interaction strongly influences the scattering and new patterns' emerge, which are determined by the distance between two vacancies. Further experiments on silicon intercalated graphene epitaxially grown on Ru(0001) shows that the experiment results are consistent with the simulated STM images based on free-standing graphene, suggesting that a single layer of silicon is good enough to decouple the strong interaction between graphene and the Ru(0001) substrate.

Effect of Monovacancy Defects on Adsorbing of CO, CO₂, NO and NO₂on Carbon Nanotubes: First Principle Calculations

We have applied density functional theory to investigate different types of carbon nanotubes (armchair (4,4)CNT and zig-zag (7,0)CNT) as sensors of some pollutant gas molecules, especially CO, CO2, NO and NO2. We show, for the first time, that the adsorption of pollutant gas molecules on carbon nanotubes are improved by introducing the monovacancy defects on the surfaces of (7,0)CNT. The adsorption energies, the optimal adsorption positions and the orientation of these gas molecules on the surfaces of carbon nanotubes are studied. It is found that the most adsorbed pollutant gas is NO molecule on (7,0)CNT.

Effects of Monovacancy on Thermal Properties of Bilayer Graphene Nanoribbons by Molecular Dynamics Simulations

The monovacancy defect effect on thermal conductivity of bilayer graphene nanoribbons(BGNs)was investigated using non-equilibrium molecular dynamics(NEMD)simulations in this work.Our results demonstrate that the presence of monovacancy defect in BGNs reduces their thermal transport properties significantly.The major finding of this work shows that the calculated thermal conductivity reduces approximately linearly with the raise of monovacancy concentration.In contrast to the temperature-dependent thermal conductivity in perfect BGNs,the thermal conductivity of defected BGNs first increases and then decreases with the increasing temperature.In addition,when the difference in the monovacancy density between two layers is larger,the thermal conductivity of BGNs is higher.We also calculated the phonon density of states,phonon relaxation time and participation ratio to provide a deeper understanding of the simulation results.Our investigation confirms that the BGNs-based nano-devices could be applied in thermal management by defect engineering.