The Modulation Of The Physical Properties Of Several Honeycomb Two-dimensional Materials And The Construction Of Interface Database

Since the first discovery,two-dimensional(2D)materials have attached great interests of researchers.Due to quantum confinement effect,2D materials exhibit many new physical properties different from that of three-dimensional(3D)materials,showing great application potential in electronic devices,electrochemistry,biomedical fields.However,some properties in pristine 2D materials may limit the direct applications.For examples,although graphene possesses ultrahigh carriers mobilities,the lack of band gap limits its application in electronic devices;The pristine honeycomb arsenene,which has been synthesized experimentally,exhibits low carriers mobilities.In order to extend the applications of 2D materials,the modulation of 2D materials is necessary.Furthermore,the substrate is essential for a real 2D material,which will modulate the structure and pristine properties of 2D materials.Therefore,the research on the modulation methods for 2D materials is of great significance.In this context,we investigated the modulations of several 2D honeycomb atomic structures and the effects on the properties.Meanwhile,we construct the 2D material-substrate interfaces database.The main results of this study are as follows:In the first work,the properties of one-third-hydrogenated(OTH)group-VA elemental monolayers,i.e.,OTH-X(X=As,Sb,Bi),were studied.The calculations of phonon dispersions show that all of the freestanding OTH-X are dynamically stable.Comparing with their pristine structure,the band gaps of OTH-As and OTH-Sb are increased to 1.619 eV and 1.268 eV,respectively,while the band gap of OTH-Bi is decreased to 0.089 eV.One-third-hydrogenation method induces the anisotropic properties to the atomic structure and electronic properties of hexagonal honeycomb lattice,which implies the OTH-X have potential applications in polarization optical devices.After hydrogenation,the carriers mobilities of OTH-As and OTH-Sb are increased by 2-3 orders of magnitude,while the electron and hole mobilities of OTH-Bi are up to 1.1×10⁵ cm²V^-1s^-1 and 1.7×10⁵ cm²V^-1s^-1,respectively.Therefore,the OTH-X holding great promise in high-performance electronic devices.Moreover,the band gap of OTH-Bi is sensitive to the strain.With the increase of the applied compressive strain,a semiconductor-metal-semiconductor transition with critical point at?=-5%is observed.This transition also implies the topological insulator to normal insulator transition.These results demonstrate strained OTH-Bi as a potential topological mechanical sensor.In the second work,we studied the structure and electronic properties of folded graphene by classical force field and first principles methods.The ideal folded graphene is a half-infinite structure,consisting of a flat double-layer graphene part and a folded edge.A large enough unitcell is used to simulate the half-infinite folded graphene and optimized by the COMPASS classical force field.We found that there is an unclosed-tube-like edge in the folded structure.The chirality index of the folded graphene is defined by referring to carbon nanotubes.Furthermore,theVan Hove singularity,which is existed in one-dimensional(1D)carbon nanotube,is found in the edge area of folded graphene by first principles calculations.The charge distributions of the flat area and the folded edge within the energy window of first Van Hove singularity under fermi-level show similar characteristic as that in double-layer graphene and carbon nanotube,respectively.These results imply that the edge of folded graphene exhibits a tube-like structure and electronic properties.This work provides a new route to construct and study complex carbon nanotube.In the third work,a high-throughput calculation workflow based on density functional theory aiming to predict the configurations of 2D material on the surface of solid is presented.The descriptor of the interface structure is defined while the lattice matching between the 2D material and the substrate is considered.All unique and irreducible interfacial structure were generated under symmetry and lattice mismatch constraints.The binding energy of interfacial system is selected as the criterion to find stable interface configurations.This method were verified by several reported interface systems,e.g.,graphene@Ru(0001),graphene@Ir(111),antimonene@Pd Te₂,and arsenene@Ag(111).The twist angle,strain,and period of 2D material on substrate interface could be predicted by this method.Meanwhile,several configurations which have not been reported,e.g.,?43@6 of graphene@Ru(0001)and many configurations of buckled arsenene@Ag(111),were also predicted.Furthermore,this method can also be applied in 2D material-2D material heterostructure.Our results provide a convenient tool to predict stable structures of 2D materials on the surface of solid and design new functional materials.