| The graphene’s zero band gap poses certain limitations to its use in some transistor electronics, because of this people begin to pay attention to other two-dimensional carbon-based materials similar to graphene. Baughman et al. predicted a new carbon allotrope-graphyne family in 1987. It’s a new kind of carbon allotropes and a two-dimensional planar network structure which composed of carbon atoms with sp and sp2-hybridized states, because of this the graphyne have abundant carbon chemical bonds, and therefore, extensive research has been put into effect. This researches reveal that the graphyne not only share some good properties of graphene, such as the good chemical stability, the high thermal stability and super high carrier mobility, but also is a admirable semiconductor which has a natural band gap, which makes graphyne has a broader application prospect. Besides, due to the existence of acetylenic linkage, graphyne possesses the exceptional ability of hydrogen storage. For a better use of graphyne in the future, people begin to tune its properties through all the ways, one of the important ways is to be hydrogenated. Lots of studies found that hydrogenation has a obvious influence on the various properties of graphyne. For example, the hydrogenation of graphyne can deteriorate the mechanical properties of graphyne, tune the band gap of graphyne and lower the thermal conductivity of graphyne. In conclusion, the hydrogenation can adjust and control the various kinds properties of graphyne. Therefore, for a better understand and taking advantages of this material farthest in the future, it’s very important to make clear the rule of hydrogenation of graphyne. We performed molecular dynamics to study the adsorption of hydrogen on graphyne, The results are mainly divided into the following parts:1 We performed molecular dynamics to research the relationship between the adsorption of hydrogen on graphyne and the hydrogen atoms’ density and the temperature. Firstly, we found that the adsorption rate of the hydrogen atoms increased gradually, in an almost linear relationship, with the increasing density of atmospheric hydrogen atoms. But due to the resistance of graphyne to be hydrogenated, containing to increase the hydrogen atoms density until close to the upper bounds of the density limit for gaseous hydrogen under normal conditions, the adsorption rate has a limit value which is nearly 37%.2 In addition, we also found that although the density of hydrogen is changing, the number of hydrogen atoms that adsorbed on acetylenic and benzene are always present certain proportion, that’s to say the relative adsorption ratio, which is nearly 7:3 at 300 K and 8:2 at 800 K.3 Then we investigated the relationship between adsorption and the temperature, the results showed that the relative adsorption ratio improved with the increasing temperature. That’s to say with the increasing of temperature, more and more hydrogen atoms were adsorbed onto acetylenic carbon atoms and fewer and fewer were adsorbed on benzene carbon atoms. In other words, raising the temperature increased the relative proportion of hydrogen atoms adsorbed on acetylenic carbon atoms at constant atomic hydrogen density.4 At last, non-equilibrium molecular dynamics simulations were applied to research the influence of the adsorption of hydrogen on the thermal properties of graphyne. The results indicated that no matter what the location the hydrogen atom adsorbed are, the carbon atoms on acetylenic or the carbon atoms on benzene, the thermal conductivity of graphyne can has a significant decrease, what’s more, the adsorption of hydrogen on carbon atoms of acetylenics can lead to a bigger reduction of the graphyne’s thermal conductivity than that on benzene. When the hydrogen atoms were adsorbed on the graphyne optionally, the thermal conductivity of graphyne decreased dramatically firstly and then go to steady. |
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