Theoretical Study On The Reduction Of Fluorinated Graphene And The Hydrogen Storage Properties Of Graphdiyne

In 2004,single-layer graphene was experimentally stripped out,which won the Nobel Prize in Physics and increased the enthusiasm for researching in two-dimensional carbon materials.Graphene have attracted great attention from scientists due to their excellent adsorption kinetics,large area,high carrier mobility and reversible hydrogen storage.However,the large-scale preparation of graphene is still a problem that plagues scientists.At present,the method of reducing graphene oxide is used in the experiment to prepare graphene on a large scale,but it has been criticized because of its wide variety of oxygen-containing groups and the tendency to agglomerate during the reaction.In this paper,the generalized gradient approximation of density functional theory is used to study the reaction process of fluorinated graphene and ethylenediamine.It has been found that both the gauche and the trans structure of ethylenediamine can be stably present,where the gauche structure ethylenediamine has higher energy and more stability than the trans structure ethylenediamine.The reaction process of the most stable gauche ethylenediamine with fluorinated graphene was studied,and similar results in the experiment were confirmed,but the reaction energy barrier was higher in the whole process.The reaction process of the second stable trans-structured ethylenediamine and fluorinated graphene was studied,and the reaction energy barrier in the main reaction channel was as low as 0.91eV,indicating that the reaction may occur under natural conditions.The F atoms on the surface of graphene fluorinated were reduced after the reaction,and graphene fluoride was transformed into graphene.The calculation of the Mulliken charge and bond energy prove that the CH₂ in the trans-structural ethylenediamine is more reactive with fluorinated graphene at the same time.In 2010,Li Yuliang's team experimentally prepared a two dimensional carbon material-graphdiyne?GDY?,which has a larger specific surface area than graphene.Based on the density functional theory,the hydrogen storage properties of GDY cells were studied by ourselves firstly,and then the geometry,adsorption mechanism and hydrogen storage structure of Y-modified GDY system were studied.It is found that the adsorption energy of GDY cells to H₂ molecules is very small.The Y modification is the most stable adsorption structure at the center of the benzene ring of GDY.The maximum adsorption energy is 6 H₂ molecules around,and the average adsorption energy is-0.314eV/H2.In order to further increase the hydrogen storage capacity,the hydrogen storage structure of two Y-modified GDY substrates was studied.The whole system can adsorb up to 14 H₂ molecules with an average adsorption energy of-0.245eV/H₂.Further analysis revealed that the adsorption of H₂ molecules in the Y-GDY system is mainly the orbital interaction between H,Y and C atoms,and the interact between positively charged Y atoms and negatively charged H₂ molecules after charge transfer.