First-principles Study Of Adsorbing Atoms On Borophene And Boron Nanowires

Since the twentieth century,scientists have been working intensively on carbon-based materials,and the discovery of graphene in particular has made it the"star"material for a while.In the periodic table of elements,boron is a close neighbor of carbon.B-based materials such as two-dimensional materials borophene and one-dimensional boron nanowires have gained a lot of attention.Since the successful experimental preparation of wrinkled phase borophene by Mannix et al.in 2016,?₁₂,?₃,and honeycomb borophene have been prepared experimentally afterwards.Based on the above four structures,many studies have been carried out on mechanical properties,thermal properties,optical properties,electronic properties,adsorption of atoms or small molecules,etc.However,these structures have been predicted theoretically by scholars before they were successfully prepared experimentally.A lot of borophene structures have been proposed by researchers through density functional theory study.Among them,the?₁borophene structure has thus attracted our attention due to its high binding energy and stability.Besides,the B₃₆clusters successfully prepared experimentally and have demonstrated that the material has great potential to expand into two-dimensional borophene materials.Moreover,The researchers have demonstrated that the B₃₆clusters are thermodynamically and kinetically stable through density functional theory study.After research,no relevant research on assembling B₃₆clusters into one-dimensional nanowires has been found,so we obtained one-dimensional nanowires by assembly for the first time and performed adsorption of atoms to modulate the electronic structure of original nanowires and properties.So in this thesis,we have done two main works as follows.(1)The geometry,electronic structure and magnetism of transition metal atoms adsorbed on?₁borophene in different ways were investigated by density functional theory.The adsorption energies of transition metal atoms adsorbed on?₁borophene in different ways are discussed;the electronic structures under different adsorption modes are performed.the thermodynamic stability of these structures are elaborated by molecular dynamics simulations;the magnetic properties of these adsorption ways are investigated.The results display that the trends of the adsorption energy of TM atoms on?₁-borophene is consistent for the three adsorption modes and is line with the B-TM binding energy of its system.Moreover,the?₁borophene was successfully tuned from metal to semiconductor under different adsorption modes,and a larger magnetic moment appeared.This conclusion provides a new idea and method for introducing magnetic moments and adjusting the band gap of metallic materials.(2)The geometry,electronic structure and stability of one-dimensional nanowires assembled by B₃₆clusters were investigated using density functional theory.The electronic structure of B₃₆clusters is discussed,and the thermodynamic stability and electronic properties of B₃₆clusters assembled into two different ways of nanowires,as well as the adsorption system with different numbers of H atoms,are investigated.The results show that both nanowires have the same energy and are thermodynamicly stable structures,showing semi-metallic and small band-gap semiconductor characteristics,respectively;both types of nanowires become semiconductors with large bandgaps after the adsorption of H(2H)atoms,and both are thermodynamically stable structures.Analyzing the calculated results of the partical density of states of the adsorbed H nanowires,it is found that the s-electrons of H are basically distributed at deeper energy levels,reflecting the stronger interaction between the H atoms and the B nanowires.