First Principles Study On The Interaction Between Surface Modification Of Graphyne And Gas Molecules

Since the first preparation of graphdiyne(GY)in 2010 years,it has attracted extensive attention from researchers.because of its unique electrical conductivity,excellent geometry and rich carbon chemical bonds.Intrinsic ?-graphiyne is a kind of excellent semiconductor with natural band gap,the highest stability in the graphiyne family,because of these excellent characteristics,so that it has the potential as a gas sensitive material.In this paper,based on Density Functional Theory(DFT)is a first-principles method was used to improve the surface chemical activity of ?-graphiyne by doping transition metal Fe atoms.The adsorption properties of ?-graptyne doped with transition metal iron atoms on small gas molecules O2,CO,NO,NO2,SO2 and NH3 were investigated.Based on the Climbing Image Nudged Elastic Band(CI-NEB)theory,the adsorption and dissociation reaction of H2 O molecules on the metal-modified graphylene surface was studied,which was expected to contribute to the application of two-dimensional graphylene materials in gas sensors and new energy fields.The conclusions are as follows:(1)Using the first-principles method within the framework of density functional theory,the adsorption behaviors of gas molecules O2?CO?NO?NO2?SO2 and NH3 on the surface of ?-graphyne doped with Fe atom were explored in detailed.It is found that dopant Fe atoms could be embedded stability into the ?-graphyne plane with the lower binding energy,the modified surface could significantly enhance the adsorption capacity for free gas molecules.Gas molecules are anchored firmly at the surfaces through the formation of chemical bonds with Fe dopant atoms,the typical chemisorption behaviors can be confirmed by the analysis of electronic properties.The O-O bond is elongated to 1.412 (?) because of the chemical interaction between adsorbed O2 and dopant surface,the production of activated oxygen radicals maybe used for elimination of toxic gases.The sensing mechanism of GY-Fe was discussed by desorption properties of gas and band structure analysis,we obtained the recovery time about 7.89 seconds for SO2 at 398 K.Therefore,this study,maybe provide some helpful informations for the design of graphyne-based gas sensors and catalysts.(2)The surface chemical activity of graphyne acetylene can be improved by doping Fe atoms.in addition,compared with the pure GY surface,the GY-Fe system can significantly enhance the adsorption of H2 O molecules.The O-H bond and H-O-H bond angles of H2 O molecule after structure optimization become larger to varying degrees,which indicates that the O-H bond can be broken if the molecule requires lower energy.The calculated energy barrier of the transition state is 0.86 e V.H2 O molecules cannot dissociate spontaneously into H and OH,and additional energy is needed to dissociate H2 O molecules.