Theoretical Investigations On The Controllable Adsorption Of Lewisite Agent By Graphene-based Materials

Nowadays,solving energy and environmental problems is a hot topic in global research.Chemical agents,which have been widely used in terrorist attacks and wars in recent years,have caused serious harm to human health,social environment and national security.Therefore,many researchers have been engaged in studying the detection and removal of harmful gases,finding an effective way to eliminate such chemical agents has become a major challenge faced by researchers.One of the most effective ways to remove chemical agents is to select a suitable adsorbent material.Graphene is a two-dimensional structure that was first discovered in2004 as a unique allotrope of carbon.Due to the excellent thermal,mechanical and electrical properties,it has become a rising star material.It is used in a variety of adsorption studies,such as adsorption of toxic gases,drug pollutants and water pollutants.In fact,the adsorption of intrinsic graphene is weak.There have been many studies that have treated the surface of graphene with various atoms,such as Ca,Li,Al,and transition metal(TM)atoms,to enhance the adsorption capacity for small molecules.In this thesis,the removal and detection performance of transition metals such as Cr,Mn,Fe,Co,Zn and Ni doped grapheme based materials and transition metals such as Mn,Fe,Ni,V and Co modified graphene for harmful gas lewisite agent are investigated.The main research results include the following three parts:(1)The adsorption of lewisite agent molecules on transition metal doped graphene materials is studied.After the transition metal atoms(Cr,Mn,Fe,Co and Ni)doping,the properties of the graphene material change obviously.In addition,we tried to use transition metal-doped graphene materials to adsorb lewisite molecule.The result of the calculation shows the enhancement of the metal-doped grapheme to lewisite molecule.We find that the electronic and optical properties of the substrate change significantly before and after the adsorption of lewisite molecules.All the changes show that the transition metal doped grapheme materials show strong adsorption ability to lewisite agent molecules.(2)Theoretical and experimental studies show that there are many ways to improve the adsorption performance of graphene by modifying methods.In addition to metal doping,metal atoms can also be adsorbed on graphene.We have experimented with the adsorption of metal atoms such as Mn,Fe,Ni,V,Zn and Co on graphene.According to the calculation and comparison of adsorption energy,we can find that Zn atom cannot be firmly adsorbed on graphene.Because the adsorption energy between Zn atom and graphene is small,that means there is a weak physical interaction between Zn atom and graphene.The other metal atoms we’ve studied are stable enough to attach to graphene.After the adsorption of metal atoms,the adsorption of graphene based materials on lewisite agent molecules also show chemical adsorption.That is to say,the adsorption of metal adsorbed graphene to lewisite agent molecules is also very strong.(3)The calculation shows that the graphene based materials doped/adsorbed by transition metal have strong adsorption ability to the lewisite agent molecule,so it is difficult to complete the recovery of the substrate material under strong adsorption.And that doesn’t fit with the idea of green chemistry.In our work,we try a method to regenerate the substrate of the adsorption system.The calculation shows that the release of the substrate material can be realized by adding electric field into the adsorption structure.The method of adding electric field has the advantages of simple operation,strong controllability and no pollution.It is find by calculation that the temperature of the adsorption system increases with the addition of negative electric field.The adsorption capacity of the graphene substrate to the adsorbed substance is reduced until the adsorbent is released.In this way,the purpose of recycling the substrate is realized.