Molecular Dynamics Of Hydrogen Adsorption On The Surface Of Graphyne

Carbon,the element responsible for life on earth,was proposed as a candidate of material for emerging electronics,never stops inspiring the enthusiasm and imagination of research due to its various allotropes from one to three dimensions.Depending on three hybridization forms(,,and),carbon can form a variety of allotropes,such as graphite and diamond existing in nature.In recent years,two-dimensional structures of carbon allotropes have become one of the most promising new materials for nanotechnology.Among them,graphene has attracted the attention of scientific community due to its superior properties.The graphene possesses excellent electronic,magnetic,thermal and mechanical properties,which regarded as a material with great potential in electronic industry,but the zero band gap of graphene provides some limitations to its use.Graphyne is another non-natural allotrope of carbon composed ofandmixed C atoms.The atomic structure of graphyne was first suggested by Baughman et al..Graphyne is a generic name for the carbon allotrope family.It is obtained by replacing one-third of the carbon carbon bonds in graphene with triple-bonded carbon linkages.Recently,experimental success has been achieved in the synthesis of graphdiyne which is a substructure of graphyne.There are several studies on different properties of graphyne and its related structures in the literature.Graphyne not only share some excellent properties of graphene,but also has natural band gap,which makes graphyne having a broader application prospect contrast to graphene,for example,it will be more suitable to apply in transistor.Although researchers can just synthesize the graphdiyne(benzenoid rings connecting two acetylene groups)so far,the first principle calculations has indicated that the graphyne(benzenoid rings connecting one acetylene group)has a better stability than the graphdiyne which has already synthesized successfully.Because of the excellent properties of graphyne,investigator paid much attention to the pristine and functionalized graphyne and graphdiyne,which illustrated the electric properties,mechanical properties,fracture mode and the geometrical features of hydrogenated graphyne and graphdiyne.The hydrogenation of graphene can open the band gap of graphene,the hydrogenation of graphyne can also adjust its band gap.A more detailed investigation depends on H/C ratio illustrated,the enlargement of the H/C ratio can lead the rapid increasing of the band gap,Such as for graphyne,if the coverage rate of hydrogen increased from 0 to 1,the band gap of graphyne can change from 0.45 eV to4.43 eV.It provided a new method to adjust the electric properties of graphyne.Since the hydrogenation has such important influence on the properties of graphyne,what is the adsorption rule of hydrogen on graphyne?In this article,we will take the graphyne as example to discuss this problem.We performed molecular dynamics to study the adsorption of hydrogen on graphyne,The results are mainly divided into the following parts:We used the Molecular dynamics method to calculate the rule of the adsorption of hydrogen on the graphyne wafer.First we calculated the relationship between the adsorption rate of hydrogen atoms on the graphyne surface and the concentration of hydrogen atoms at room temperature and pressure of 300 K and 1.01×10~5 Pa.The results of our simulation show that the adsorption rate of carbon atoms on the surface of hydrogen atom and graphene increases linearly with the increase of hydrogen atom concentration.At the same time,we found that there was a maximum value of hydrogen atom's adsorption rate on the surface of graphene at room temperature and pressure of 300 K and1.01×10~5 Pa,which was about%37.In our simulation,we also found that the ratio of the number of hydrogen atoms adsorbed at different positions on the graphene surface did not change significantly at the same temperature.In other words,at the same temperature,the ratio between the number of hydrogen atoms on the acetylene chain adsorbed by hydrogen atoms on the surface of graphene and the number of hydrogen atoms on the benzene ring adsorbed on the surface of graphene does not change much.That is,the ratio between the number of atoms successfully adsorbed on the acetylene chain and the number of atoms successfully adsorbed on the benzene ring is defined as the relative adsorption rate.We calculated the ratio between the number of hydrogen atoms successfully adsorbed on the acetylene chain on the graphene surface and the number of hydrogen atoms successfully adsorbed on the benzene ring at 300K,that is,the relative adsorption rate is about 7:3 at 800 K,the relative adsorption ratio was about 8:2.We also studied the relationship between the relative adsorption ratio of hydrogen atoms on the acetylene chain and on the benzene ring and the temperature change at the same concentration of hydrogen atoms.We found that the relative adsorption rate increased with the increase of temperature,indicating that with the increase of temperature,the number of hydrogen atoms adsorbed on the acetylene chain increased,while the number of hydrogen atoms adsorbed on the benzene ring decreasedIt can be seen that at the same concentration of hydrogen atoms,the relative pair adsorption ratio between the acetylene chain adsorbed by hydrogen atoms and the benzene ring of graphene can be increased by increasing the temperature.