Studies On The One-dimensional Restricted Ethanol And The Hydrogen Storage Properties Of Silicon Carbide Nanotubes

Nanomaterials can be used as prototype materials in many fields of simulation calcula-tion.With the development of research,there are many kinds of nanotube structures.Carbon nanotubes（CNTs）and silicon carbide nanotubes（SiCNTs）have been widely used as fuel cell carriers and hydrogen energy carriers because of their excellent electrical and structural properties.CNTs can influence the dynamics of molecules in the microscopic field.Ethanol is a large molecule which is used in biology and chemistry and has the function of regulating ion channels.It is of great significance to study its molecular behavior in nanotubes.However,this kind of systematic study is still very few.Therefore,we simulate the bound ethanol molecules in single-walled carbon nanotubes（SWCNTs）based on molecular dynamics.Since the 1970s,hydrogen energy has become a hot topic in the field of energy research as a clean and secondary energy source.However,the existence of hydrogen in the form of gas under normal temperature and pressure and its flammable and explosive chemical properties lead to a safe and effective hydrogen storage way to be further explored.Therefore,we simulated the hydrogen storage performance of single-walled SiCNTs doped with chiral parameters of（6,6）based on density functional theory.The main research contents of this article are as follows:In the first part of my work,the structure and kinetic properties of ethanol molecules in nanotubes with different diameters were studied based on molecular dynamics simulation.Eight SWCNTs with different diameters were selected to simulate the nanoscale channel-s.The average number of ethanol molecules in SWCNTs increased monotonically with the increase of the diameter of SWCNTs.However,the average hydrogen bond number and hy-drogen bond lifetime of each ethanol molecule varied nonmonotonic with the diameter of SWCNT,and the properties of ethanol molecules were largely dependent on the diameter of the nanotubes.The diffusion rate of ethanol molecules in SWCNT firstly increased and then decreased with the increase of the diameter of SWCNT.The non-monotonic dependence of the diffusion rate on the diameter of SWCNT may be related to several factors,such as hy-drogen bond characteristics,ethanol-tube interaction,redirection characteristics,etc.In the second part of my article,based on First-principle,the hydrogen storage perfor-mance of substituted doping SiCNTs was studied.The C site and Si site in SiCNTs were replaced by S element and P element respectively,and the Mulliken concentration number,net charge,energy band,density of states and other relevant parameters of the doped system were calculated and analyzed.The data show that the two different doping forms have differ-ent adsorption methods for hydrogen outside the tube.When the C site in SiCNTs is replaced,the band gap of the doped structure decreases,and the interaction force between the tube wall and₂is stronger.This hydrogen adsorption behavior is chemisorption.However,when Si site is replaced,doping has no obvious effect on the electronic structure of the material,and only a small amount of charge transfer occurs.This hydrogen adsorption behavior is physical adsorption.The high efficient hydrogen sensing properties of S and P doped SiC nanotubes studied in this article can provide some ideas for their application in the field of hydrogen storage.