Thermal Conductivity Of Graphyne Nanoribbons:a Molecular Dynamics Simulations

Graphyne, another non-natural allotrope of carbon, is a new kind oftwo-dimensional planar network structural all-carbon molecules and of the samesymmetry as the graphene, but more carbon chemical bonds. Some studies reveal thatthe graphyne nanoribbons have some similar properties to graphene like high carriermobility, excellent chemical and thermal stability.However, there are some differentcharacters to graphene due to the introduction of acetylenic linkage, for example,graphyne is a semiconductor and has the exceptional ability of lithium and hydrogenstorage etal. These intriguing characters indicate the applications of graphyne in thefield of optoelectronic devices and energy storage. So it is necessary for theacceleration of graphyne’s applications to investigate the thermal properties ofgraphyne nanoribbons systematacially.In this paper, the nonequlibrium molecular dynamics simulation is used toinvestigate the thermal conductivity of graphyne nanoribbons. The results are dividedinto some sections as follow：1. Nonequlibrium molecular dynamics method is adopted to study the thermalconductivity of graphyne nanoribbons with the length, width, edge shapes,temperature and hydrogen. The results demonstrate that the thermal conductivity ofgraphyne nanoribbons increases with the increasing of length, and it follows thepower of k~L with the length. It is also found that with the width, the thermalconductivity of graphyne nanoribbons always increases. This is attributed to thedecrease of edge phonon scattering effect with the width.2. The phonon densties of states and the phonon mode are used to explain themechanism of the difference of thermal conductivity between graphyne and graphene,between ZGYNRs and AGYNRs.3. We have simulated the thermal conductivity of graphyne nanoribbons withstrain and temperature. The results reveal that the thermal conductivity of graphynenanoribbons decreases with the tensile strain. Its thermal conductivity also decreaseswhen the graphyne nanoribbons are subjected to the compressional strain. It is alsofound that with the increasing of temperature, the thermal conductivity of graphynenanoribbons first increase and then decrease gradually.4.We have studied the effect of hydrogen with the different concentration and position on the thermal conductivity of graphyne naoribbons. The results indicate thatthe thermal conductivity of graphyne nanoribbons is sensitive to the hydrogenconcentration, particularlly the small concentration. Thermal conductivity of graphynenanoribbons decreases with the increasing of hydrogen concentration. We also findthat the hydrogen at the acetylenic linkage leads to more bigger reduction of themalconductivity than the hydrogen at the benzene ring. This is due to the more lowfrequency phonons excited in the acetylenic hydrogenated graphyne nanoribbons.