Study On The Effect Of Non-metallic Atomic Doping On The Adsorption Of Electron Structure Of Small Molecules On α-Graphyne

In recent years,two-dimensionalelectronic materials research attracts great interest to researchers,and their electronic structure and properties can be modified by doping and adsorption.Graphyne as a rising two-dimensional（2D）carbon allotrope,it is an all-carbon molecule with two-dimensional planar network structure formed by a number of acetylene bonds conjugated by benzene ring.The high activity of each acetylene bond unit in its structure makes it more advantageous than graphene in doping and adsorption of small molecules.In addition,with the deepening of scientific research,graphyne has shown more superior properties and functions in many fields such as electronics,environment,catalysis,energy and so on.α-graphyne as an important part of graphyne family,because it has to the electronic structure and properties of graphene is similar:near the Fermi level showed obvious semi-metallic,has excellent electronic and optical properties,and also has high activity acetylene bond units which are not known to graphene,so it attracts the interest of researchers.However,as far as we know,a few literatures have reported the magnetic and electronic structures of doping and adsorption of small molecules in single-layerα-graphynes.In this paper by using Density Functional Theory（DFT）based on first-principle calculation method,and take single-layerα-graphynes as the research object,we systematically studied the doping of N,O,P in single-layerα-graphynes and its effect on the electronic properties and magnetic properties of H,O,OH and H₂O adsorption.The main conclusions of this paper are summarizedas follows:1.Electronic properties and magnetic properties of H₂O,H,O and OH adsorbed on the surface of monolayerα-graphynes.We mainly studied the interaction of H₂O,H,O and OH adsorbed on the C-atom apex of sp hybridization in a defect-free pristine monolayerα-graphynes.The results show that after adsorption,the bonding between H₂O molecules and the substrate surface is weak,and H₂O adsorption is mainly van der Waals interaction.After H and OH adsorption,the systems showed magnetism,while the adsorption systems of O atom and H₂O molecule showed no magnetic moment.In addition,compared with other adsorption systems,O atom adsorption system has the lowest adsorption energy,while H₂O molecule adsorption system has the highest adsorption energy,indicating thatα-graphynes is the easiest to adsorb O atom,while H₂O molecule is the most difficult to adsorb.After adsorption,compared with H atom OH and H₂O molecular adsorption system,the number of charge transfer between the O atom and substrate is the largest,indicating that the O atom is most likely to interact with the substrate.Moreover,impurity states were observed near the Fermi level after the adsorption of H O atoms and OH,while no impurity states were observed after the adsorption of H₂O molecules.Our study will provide a favorable theoretical basis for the design and research of theα-graphyne gas sensor.2.Effects of 2p atoms（N O）doping on the electronic properties and magnetic properties of H₂O,H,O and OH adsorbed on the surface of monolayerα-graphynes.We have examined the interaction of H₂O and H,O and OH on the pristine and dopedα-graphynes,respectively.The results are shown that doping of N and O atoms and adsorption of small molecules can change the electronic structure and magnetic properties of single-layerα-graphynes,and the position structure of sp hybrid carbon atoms in single-layerα-graphynes is the most stable.In addition,the adsorption ability ofα-graphynes to small molecules is obviously enhanced after doping of N and O atoms.The magnetic properties of H,O atoms and OH adsorbed on pristineα-graphynes show obvious differences before and after the doping of N and O atoms:H atoms and OH adsorbed on pristineα-graphynes show magnetism;after doping of N atoms,the magnetism disappears,while after doping of O atoms,H atoms show magnetism,but the magnetism of OH adsorption system disappears;however,O atoms adsorbed on pristineα-graphynes do not show magnetism.Magnetism occurs when N atoms are doped,but O atoms doped do not change the magnetism of O adsorption system.In addition,the adsorption of H₂O molecule byα-graphynes is weak,which is influenced by van der Waals effect and belongs to physical adsorption.This study will provide new ideas for the detection of N and O impurities inα-graphynes and the design ofα-graphynes gas sensor.3.The influence of 3p atom（P）doping on the electronic structure of small molecules adsorbed byα-graphynes.We mainly studied the effect of P atom doping on the electronic properties of H,O,OH and H₂O adsorbed on the surface of single-layerα-graphynes.Our results show that the position structure of sp hybridized carbon atoms in single-layerα-graphynes is the most stable,and that P atom doping can change the electronic structure and magnetic properties of H,O,OH and H₂O adsorbed on single-layerα-graphynes.The adsorption performance ofα-graphynes to O atom is always better than that of H atom,OH and H₂O molecule before and after P atom doping.Moreover,P atom doping enhances the adsorption performance ofα-graphynes to H₂O,H,O and OH.The magnetic properties of H,O and OH adsorbed on the pureα-graphynes show obvious differences before and after the P-doped system:H and OH adsorbed on the pureα-graphynes show magnetism,and the magnetism disappears after the P-doped system;while O atom adsorbed on the pureα-graphynes shows no magnetism,and the system appears magnetism after the P-doped system.In addition,according to the changes of electronic structure and magnetic properties before and after adsorption,H,O and OH adsorption can be used to determine whether P atom impurities are introduced into single-layerα-graphynes.Our research has deepened the understanding of the properties of P doping and adsorption of H,O,OH and H₂O on the surface ofα-graphynes,and laid a foundation for further research on the doping and adsorption of other 3p atoms.