Enhanced Methane Storage in Graphene Oxide Induced by an External Electric Field: A Study by MD Simulations and DFT Calculation

Abstract

To improve the methane (CH 4 ) storage performance of graphene oxide (GO), molecular dynamics (MD) simulations and density functional theory (DFT) calculation were employed to investigate the effect of electric field (EF) on the adsorption and desorption performances of monolayer graphene modified with three oxygen-containing functional groups (hydroxyl, carboxyl, and epoxy) as the CH 4 storage material. Through the calculation and analysis of the radial distribution function (RDF), adsorption energy, adsorption weight percentage, and the amount of CH 4 released, the mechanisms of influence on adsorption and desorption performances caused by an external EF were revealed. The study results showed that the external EF can significantly enhance the adsorption energy of CH 4 on hydroxylated graphene (GO-OH) and carboxylated graphene (GO-COOH), making it easier to adsorb CH 4 , and improve the adsorption capacity. Whereas the EF severely weakened the adsorption energy of CH 4 on epoxy-modified graphene (GO-COC) and reduced the adsorption capacity of GO-COC. For the desorption process, applying the EF can decrease the CH 4 release of GO-OH and GO-COOH but increase the CH 4 release of GO-COC. To sum up, when an EF is present, the adsorption properties of −COOH and −OH and desorption properties of −COC will be improved, but the desorption properties of −COOH and −OH and the adsorption properties of −COC will be weakened. The findings in this study are expected to propose a novel non-chemical method to improve the storage capacity of GO for CH 4 .

Study on Molecular Model Construction and Gas Adsorption Simulation of Anthracite in the Qinshui Basin

“…China has abundant reserves of coalbed methane resources, with a total of 36.8 trillion m 3 coalbed methane buried below 2000 m. In the future, coal resources will be the foremost energy resource in China for a long time, and the share of coal resources in the energy mix will continue to rise. − However, the determination of the occurrence law of coal seam gas is still faced with various problems, such as large errors in measuring the gas content of gas enrichment areas and considerable difficulty in quantitatively displaying distribution patterns of heterogeneous gas-containing space. These problems directly affect the accuracy of coal seam gas extraction, making it difficult to thoroughly eliminate gas disasters. , Meanwhile, coal is a typical complex organic material, , with significant diversity and heterogeneity in its structure at the microscale.…”