Research On Mechanical Properties And Sodium Storage Application Of Two-Dimensional N-doped Graphene/Phosphorene Heterostructure

Phosphorene is a two-dimensional material with a folded honeycomb layered structure.Due to its excellent optical,electrical,and magnetic properties,it has great application potential in the fields of transistors,photocatalysis,and batteries.However,exposure to air will cause severe oxidation on the surface of the phosphorene,which inhibits its practical application.But,by combining phosphorene with another two-dimensional matrix material with good chemical stability(such as graphene)to form a two-dimensional heterostructure,the surface oxidation of the phosphorene can be effectively suppressed.However,compared to pristine graphene,N-doped graphene has been proposed to be one of the most promising capping substrates because of its significant modified properties such as semiconductivity,surface reactivity,biocompatibility,synergistic function with various functional materials,which can replace pristine graphene as a matrix protective material of phosphorene.This paper systematically studies the mechanical properties and sodium storage properties of two-dimensional nitrogen-doped graphene/phosphorene heterostructure.The main work and contents are as follows:(1)In theory,four types of two-dimensional phosphorene/graphene heterostructures are designed,which are composed of pristine graphene and three common types of nitrogen-doped graphene(graphitic-N,pyridinic-N,and pyrrolic-N doped graphene)with 2D phosphorene.By first-principles calculations,the geometric structure,electronic properties and mechanical properties of the four heterostructures were systematically studied.The calculation results show that all the four kinds of two-dimensional heterostructures have good stability.And,each heterostructure inherits the excellent mechanical properties of the graphene substrate,endowing it with good ability to resist damage.In addition,each heterostructure retains the characteristics of itself.Compared with the pristine graphene/phosphorene heterostructure,the doping N atoms changes the electronic structure of the pristine graphene,and the electrical conductivity of the N-doped graphene/phosphorene heterostructures are improved.In terms of mechanical properties,the four heterostructures exhibit different degrees of anisotropy.Among them,the graphitic-N doped graphene/phosphorene heterostructure has the largest Young's modulus of 435.65 N/m,and the pristine graphene/ phosphorene heterostructure has the highest ultimate strength of 47.94 N/m.(2)In order to explore the sodium storage properties of the four heterostructures,the adsorption energy and the diffusion property were calculated respectively.The results show that the pyridinic-N doped graphene/phosphorene heterostructure and the pyrrolic-N doped graphene/phosphorene heterostructure have high sodium adsorption activity.Diffusion properties calculation results show that the presence of phosphorene reduces the migration barrier of sodium atoms on the surface of three types of N-doped graphene,making sodium diffuse faster on the graphene surface.In addition,the adsorption energy of sodium atoms between the interlayer of four heterostructures is stronger than that on the heterostructure surface.The migration energy barrier of sodium between pyridine-N doped graphene/phosphorene heterostructure and pyrrolic-N doped graphene/phosphorene heterostructure layers is lower than that of the respective graphene surface.