| In view of the experimental progresses in fabricating boron and carbon nanostructures,we have carried out detailed investigations the structure and application of new two-dimensional（2D）boron and carbon allotropes by using the density functional theory calculations.First of all,the assembly paths of a 2D porous carbon allotrope designed with acepentalene organic molecules are rationally proposed in theory.The polymerized acepentalene membrane sheet with hexagonal conjunction（h-PAMS）shows high stability.Itsπ-bands hold Dirac fermion-like characteristics,with the Dirac point located below the Fermi level at theΓpoint,crossing the Fermi surface to enable high mobility charge carriers.In addition,it has anisotropic in-plane mechanical properties and can withstand strain loading as large as 0.9 eV/atom energy cost against structural collapse,supports its potential application in high-performance nano conductive materials.Secondly,the application potential of h-PAMS structure in the field of lithium ion batteries is mainly explored.We have calculated the storage and diffusion behavior of lithium in h-PAMS monolayer and bulk structure.The synergistic effects of Li adsorption and Li surface clustering result in 676 mAh/g capacity with a low average open-circuit voltage.Furthermore,the barriers for Li diffusion on the h-PAMS and penetration through the porous hole are only 0.35 and 0.61eV,respectively.The space expansion during the charge-discharge process is only about 10%of the stacked multilayer.Therefor,h-PAMS material has great potential as anode material of lituium ion batteries.Finally,the transition metals and two layers of hexagonal honeycomb boronphene were introduced to form a sandwich structure to stabilize the honeycomb boronphene which was separated from the substrate.We optimized the structure composed by transition metal monatomic and dimer as the junction of two layers of honeycomb borophene,and screened five structures which were stability from the aspects of energy,mechanics and thermal.Five structures are as follows,the TaB2 forγ-TMB2 and MoB4,TaB4,WB4,ReB4 forα-TMB4.The electronic properties of WB4 and MoB4 with double Dirac cone are analyzed,and the origin of double Dirac cone in the structure is expounded.Under biaxial stress within 10%,the Dirac cone was well preserved,which laid a foundation for its application in high-performance nanometer conductive materials. |
