First Principle Study On The Doping And Adsorption Of Graphenes

Since graphene was synthesized in experiment in 2004,graphene has attracted extensive attention for its rich and novelty electrical and magnetic properties.Graphene has low resistivity and very high electron mobility,and it has been predicted to replace silicon as the next generation of materials for nanoelectronics.In the past decade,graphene has make remarkable progress in microelectronics,materials,information,energy,environment and biomedicine.In order to obtain various graphene-based electronic devices,it is necessary to modulate the electromagnetic transport properties of the graphene.Doping and adsorption are effective ways to modify and modulate the structures and properties of graphene.The application of graphene in nano-electronic devices can be greatly expanded by cutting two-dimensional graphene structure into one-dimensional graphene nanoribbons.Besides the monolayer graphene,the bilayer graphene has unique electronic properties compared with that single layer graphene,but there are few investigations on the bilayer graphene.In this paper,we have studied the elctmonic properties of zigzag and linear transition metal Ti atomic chain adsorption on the surface of armchair graphene nanoribbons?AGNR?by the first principle method based on density functional theory.For the different width of nanoribbons,we discusse the modulate regulation of the electronic properties by the Ti atomic chain.In the next place,we have investigated the structural,electronic magnetic properties of gas molecules?CO₂,CH₄ and H₂O?adsorption on the surface of Cr doped bilayer graphene.Some important results are concluded as follows:?1?For the relaxed geometry structure,the Ti atomic chains can be steadily adsorbed on the surface of AGNR,and the adsorption systems are relatively stable for the zigzag and linear Ti atomic chains on the edge of nanoribbons?10ZG-1,11ZG-1,12ZG-1,13ZG-1,10LG-1,11LG-1,12LG-land 13LG-1?.The stability of adsorption systems increases with the increase of the width of nanoribbons.The electronic structure of the adsorption systems are found to depend strongly on the width of the nanoribbons.There are half-metal characters for Ti chains adsorption on 10ZG-1,10ZG-2,11G-2 and 13LG-2 systems and other adsorption systems always become metallic.The interaction between zigzag and linear Ti atomic chains and nanoribbons make the adsorption systems have magnetic moments,and the magnetic properties of the systems are derived from the Ti atoms.When the zigzag Ti atomic chains are adsorbed on the edge hollow position of the nanoribbons,the magnetic moments of TiA atoms are less than that of the TiB.As the position of the Ti atomic chains moving to the middle symmetrical position of the AGNR,the difference of magnetic moments will be decrease between the TiA and TiB atoms.These results indicate that the adsorbed zigzag and linear Ti atomic chains can effectively modify the electrical and magnetic properties of graphene nanoribbons.?2?The gas molecules?CO₂,CH₄ and H₂O?can be adsorbed steadily on the surface of the Cr doped bilayer graphene,and all the adsorbed systems are physical adsorption.The optimal adsorption structure is O₁,C₁ and H₃ for CO₂,CH₄ and H₂O,respectively.We found that CO₂ and CH₄ were easy to adsorb on surface models of Cr-doped bilayer graphene.The electronic structures of the adsorption systems are different depending strongly on the adsorbed ways of CO₂,CH₄ and H₂O.There are strongly metallic character for the O₁,C₁,H₁,H₂ and H₃ adsorbed ways of the gas molecules CO₂,CH₄ and H₂O.The gas molecules adsorption systems have magnetic moments which mainly come from Cr atoms.The research results can provide important theoretical basis and experimental guidance for nano-electronic devices.