▎ 摘　　要

Effective CO2 capture and sequestration (CCS) is an urgent issue concerned with the control of the effects of global warming and restriction of the proliferation of environmental pollution. Using density functional theory (DFT) calculations, the imposition of an external electric field on Ca-decorated graphene (Ca-graphene) is firstly proposed as an effective means of achieving tunable CCS application. The results show that the adsorption energy of gas molecules (Delta E-gas) (including CO2, N-2 and CH4 molecules) on pristine graphene is largely enhanced by Ca-decoration, especially for CO2 adsorption. Interestingly, Delta E-gas become adjustable in the presence of an external electric field. CO2 molecule is more preferentially adsorbed on Ca-graphene than N-2 and CH4 ones whether under a positive or negative electric field. Bearing in mind that Delta E-N2 decreases under a positive electric field while Delta E-CH4 decreases under a negative electric field, we can predict that a positive electric filed is favorable for CO2/N-2 separation while a negative electric field is appropriate for CO2/CH4 separation. Our results provide a general picture on the interaction between gas molecules and Ca-graphene with or without an external electric field. We predict that CCS process can be modulated via proper metal decoration and controlling electric field intensity and direction.