A DFT study of H2S, H2O, SO2 and CH4 Adsorption Behavior on Graphene Surface Decorated with Alkaline Earth Metals

The adsorption of CH4, H2S, SO2 and H2O by alkaline earth metal (AEM) decorated double vacancy graphene (DVG) was investigated with the first principles method. The most stable adsorption configurations, adsorption energy, density of states, and charge density distributions of CH4, H2S, SO2 and H2O on AEM_DVG have been discussed. The calculated delta E-ads values of all gas molecules on AEM_DVG show that there was a weak interaction between CH4 and AEM_DVG, while the other molecules present favorable interaction with AEM_DVG. Notably, the Ba_DVG is demonstrated to have a more practical CH4 desorption temperature, as well as a broader window for the selective adsorption of CH4 over H2S, SO2 and H2O. This considerable promotion is ascribed to charge transfer and weak covalent interaction between Ba and gas molecules.