Simulation Of Methane Storage By Functional Graphene Under Electric Field Synergism

Natural gas is a mixture of hydrocarbon gases,the main component of which is methane（CH₄,about 70-90%）.Compared with oil,natural gas is a cleaner and more environmentally friendly energy source.The large-scale use of natural gas has now become an inevitable trend.However,in its large-scale use,how to improve the storage capacity of methane in a safer and more economical way is an important research content.Therefore,the effects of electric field（EF）on the process of CH₄ storage by three types of functional graphene are studied from the microscopic level by molecular dynamics simulation and density functional theory calculation,providing a new idea for efficient CH₄ storage.The research contents of this paper are:（1）In order to explore the microscopic mechanism of the effect of EF on the adsorption of CH₄ by graphene oxide,molecular dynamics simulation was employed to investigate the effect of EF on the performance of monolayer graphene modified with three oxygen-containing functional groups（hydroxyl,carboxyl and epoxy）as CH₄ storage material.When EF was present,the adsorption properties of-COOH and-OH and desorption properties of-COC would be improved,and the desorption properties of-COOH and-OH and adsorption properties of-COC would be weakened.Through the calculation and analysis to radial distribution function,interaction energy,potential of mean force,adsorption weight percentage and CH₄ release amount during adsorption and desorption,the mechanism of influence to adsorption and desorption performance by three oxygen-containing functional groups modified graphene caused external EF was further revealed.（2）In order to explore the effect of EF on the performance of two configurations of monolayer graphene oxide modified by three transition metals（Pd,Cu and Pt）as storage CH₄ media,density functional theory calculation method was employed to simulate six different CH₄ storage systems without applying EF and applying EF of 0.1V/（?）strength.The EF severely inhibited the adsorption of CH₄ by Pd-GO（Ⅰ）,Cu-GO（Ⅰ）and the two configurations of Pt-GO,and promoted the adsorption of CH₄ by Pd-GO（Ⅱ）and Cu-GO（Ⅱ）.Through the comparison and analysis to the adsorption energy,the amount of transferred charge,charge differential density diagram,band structure and state density,the mechanism of adsorption of CH₄ by three transition metal-modified GO caused external EF was further revealed.（3）In order to explore the effect of EF on the performance of monolayer GO modified with two non-metallic elements（N and B）as storage CH₄ medium,the density functional theory calculation method was employed to apply EF of different strengths to the adsorption system during the simulation process.The results showed that the EF hindered the adsorption process of N-GO-CH₄ and B-GO-CH₄ adsorption systems.Through the comparison and analysis to the adsorption energy,the amount of transferred charge,charge differential density diagram,band structure and state density,the mechanism of adsorption of CH₄ by two non-metallic elements modified graphene oxide caused external EF was further revealed.