摘要
As the greenhouse effect concerns increases,the development of new materials for the efficient capture and separation of CO_(2)gas from gas mixtures has become a matter of urgency.In this study,we performed density functional theory(DFT)calculations to investigate the adsorption and separation behavior of CO_(2)/CH_(4)/H_(2)on the surface of two-dimensional(2D)Al_(2)C materials under positive/negative applied electric fields.In the absence of an electric field CO_(2)is weakly physisorbed on the Al_(2)C surface,but with the application of an applied electric field,the adsorption state of CO_(2)gradually changes from physical to chemisorption(adsorption energy changes from-0.29 e V to-3.61 e V),while the negative electric field has little effect on the adsorption of CO_(2).We conclude that the C=O bond in adsorbed CO_(2)can be activated under an external electric field(maximum activation of 15%under an external electric field of 0-0.005 a.u.).Only in the presence of an applied electric field of 0.0033 a.u.and temperatures above525 K/675 K can the adsorption/separation reaction of CO_(2)single adsorption and CO_(2)/CH_(4)/H_(2)mixture be spontaneous.The adsorption/desorption of CO_(2)on Al_(2)C nanosheet in an electric field of 0.003-0.0033 a.u.is all exothermic,which can be easily controlled by switching on/off the electric field without any energy barriers.The capacity of Al_(2)C to capture CO_(2)per unit electric field decreases with increasing CO_(2)concentration,but still has efficient gas separation properties for CO_(2)/CH_(4)/H_(2).Our theoretical results could provide guidance for designing high-capacity and high-selectivity CO_(2)capture materials.
基金
funded by the National Natural Science Foundation of China(No.21603109)
the Henan Joint Fund of the National Natural Science Foundation of China(No.U1404216)
the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.20JK0676)。