Theoretical Study On The Interaction Of Graphene Interlayer Regulated By Superatoms

Superatoms can exhibit atomic-like arrangements in their electronic structure,and the types of superatom can be greatly enriched by controlling their composition and size,etc.This gives a great potential for superatoms to simulate and replace atoms and even break through the limitation of a finite number of natural elements.The rich variety of superatoms also offers the potential to provide more options for conventional membrane separation processes.Especially considering the unique two-dimensional confinement effect of graphene,which can bring clear selectivity and high permeability,it is considered as a highperformance separation membrane material and has attracted wide attention.However,previous studies have typically relied on atomic or nanoparticle control of the interlayer spacing of graphene,which is limited by the limited types of atoms that can be embedded between graphene layers and the challenge of producing nanoparticles in uniformly size.There are two potential difficulties associated with this approach.Firstly,the types of atoms that can be embedded between graphene layers are limited.Secondly,achieving uniform preparation of nanoparticles is challenging.These factors have impeded the further development of regulating the interlayer spacing of graphene.However,with the continuous development of the ability to uniformly prepare and modulate the performance of superatoms,there is hope for new methods to regulate graphene separation membranes.In this paper,based on atomic-level structure calculations and dynamic simulations,we discovered a new way to modulate the interlayer spacing by changing the areal density of superatoms and explored a new direction of jointly modulating the charge and superatomic areal density to regulate graphene separation membranes.These advances provide an important reference for related studies of interlayer interactions between graphene layers.First of all,we theoretically inserted Au20 superatoms which can be synthesized experimentally into the bilayer graphene to form the graphene-Au20-graphene system(graphene-Au20-graphene,GAG).Through the use of density functional theory calculations and molecular dynamics simulations dominated by tight binding,we discovered that the graphene layer spacing is regulated by changing the superatomic areal density(areal density = superatom(number)/ area of graphene(?2)).Specifically,it was found that the graphene layer spacing increased from 9.3 to 11.4 A as the areal density increased from 2.1×10-3 to 4.0×10-3 superatom/?2.However,when the superatomic areal density is as low as 1.6×10-3 superatom/ ?2,the superatomic structure is broken and cannot support graphene.Electron structure analysis shows that the Au20 superatomic orbitals in the supported GAG system are consistent with those in the non-confinement environment.This suggests that the structural robustness of superatoms is a key factor in regulating graphene layer spacing.Further energy decomposition analysis shows that the dispersion interaction dominates the physical adsorption state between the superatoms and graphene and directly affects the graphene interlayer distance.In addition,the localized orbits between graphene and superatoms also stabilize the graphene layer spacing.Therefore,the regulation of graphene layer spacing using superatoms has great potential,and it is hoped that this study will contribute to the further development of graphene separation membranes.Considering that in the above research,the Au20 superatomic structure is disrupted when the superatomic areal density is low(1.6×10-3 superatom/?2),which cannot achieve the goal of supporting graphene.Therefore,we further explored the feasibility of supporting graphene at low areal density by changing the charge state of the GAG system.Using structure calculations and dynamic simulations mainly based on tight-binding density functional theory,we found that the Au20 superatom still could not support the graphene layer at the low areal density of 1.6×10-3 superatom/?2 when the charge amount of the GAG system was 1±,2±,3±,and 4±.However,when the charge of the GAG system was6± and 8±,it was possible to successfully support the graphene layer at a low superatomic areal density.Specifically,as the charge changes from 6+ to 8+ and from 6-to 8-,the interlayer spacing of the graphene increases from 13.28 ? to 14.64 ? and from 13.44 ? to14.73 ?,respectively,while the structure of the Au20 superatom remained intact.Electronic structure analysis shows that,based on the structural characteristics of Au20 itself,the increase or decrease of charge effectively weakened the electron transfer between graphene and Au20,thus facilitating the regulation of interlayer spacing support under the low areal density of superatoms.Our findings will provide a reference for achieving composite control of graphene separation membranes based on charges and superatoms.In summary,through the research conducted in this paper,it was found that superatoms can effectively regulate the interlayer spacing of graphene.Furthermore,we have proposed a way to regulate the interlayer spacing of graphene through the joint use of charge and superatoms.These findings provide new ideas for the study of graphene separation membranes.The work in this paper has also deepened our understanding of the potential applications of superatoms.It is hoped that these discoveries will provide important references for the research of superatoms and graphene separation membranes and provide a theoretical basis for constantly expanding the application prospects of superatoms.