| As a discipline with a strong applied background,the development of surface physics provides a strong support for the progress of modern science and technology.In recent years,extensive research on the growth of nanomaterials has made the study of surface adsorption properties one of the most dynamic research directions in surface physics.The surface passivation and surface buffer can significantly regulate the properties of surface adsorption.Therefore,this is also an important research topic in surface physics.At present,the growth of silicene thin films and transition metal monatomic catalysts are two problems that need to be solved.This is mainly due to the complex interaction between these materials and the substrate,which undermines their unique electronic properties.Therefore,research on the adsorption properties of these materials when they grow on the substrate can help to understand the interaction between them and the substrate,and thus find the substrates suitable for their growth.Using the first principle calculations based on density functional theory,this paper has systematically studied the changes of adsorption properties of these two nanomaterials when grow on the specific substrates.It is found that the surface passivation and surface buffer layer methods can be used to regulate the adsorption properties of these surface systems,so as to achieve better adsorption and growth.In the first part of this paper,the electronic properties of silicene adsorbed on Si(111)surface are systematically calculated.First,we found that growing silicene directly on the Si(111)surface completely destroys the unique electronic structure of silicene.Therefore,an important surface modification method is used in the research,that is,by using surface passivation method,the substrate is changed from a metallic surface 'to a semiconductor surface with a certain band gap.Our surface system introduces a 1/3 ML coverage of bismuth atoms to completely passivation of Si(111)(?3×?3)surfaces.The calculated results show that the surface of Si(111)(?3×?3)after complete passivation of bismuth atoms is a semiconductor surface with a band gap greater than 0.75 eV.Such a semiconductor surface is not only suitable for silicene growth,but also retains the unique electronic structure properties of silicene.Such theoretical research results have a certain guiding significance for the experiment and can help the experiment to grow large areas and high-quality silicene films fster and better.The second part of the paper has systematically calculated the electronic properties of 3d transition metal vanadium atoms adsorbed on the Cu(111)surface.First,the calculated results found that the direct adsorption of vanadium atoms on the Cu(111)surface cannot allow vanadium atoms to be stably adsorbed on the most surface of the substrate,and the position of vanadium atoms and copper atoms of the substrate will be reversed.As a result,the vanadium atom is adsorbed in the substrate,destroying most of the electronic properties of the single vanadium atom.Therefore,another important surface regulation method was used in the study,namely the introduction of a graphene buffer layer between vanadium atoms and the Cu(111)surface.The introduction of graphene buffer layer not only allows vanadium atoms to be stably adsorbed on the most surface of the substrate,but also allows it to retain some electronic properties of the single vanadium atom.The results of this study have some reference value for the single-atom catalytic application based on vanadium atoms.In short,the effect of surface passivation and surface buffer layer on surface adsorption properties is systematically studied by using the first principle calculation method.The results show that the substrate can be improved by means of surface passivation and surface buffer layer,which becomes more favorable to the growth of silicene films and the stable adsorption of 3d transition metal vanadium atoms on the Cu(111)surface. |
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