Electric field controlled CO₂ capture and CO₂/N₂ separation on MoS₂ monolayers

Developing new materials and technologies for efficient CO₂ capture, particularly for separation of CO₂ post-combustion, will significantly reduce the CO₂ concentration and its impacts on the environment. A challenge for CO₂ capture is to obtain high performance adsorbents with both high selectivity and easy regeneration. Here, CO₂ capture/regeneration on MoS₂ monolayers controlled by turning on/off external electric fields is comprehensively investigated through a density functional theory calculation. The calculated results indicate that CO₂ forms a weak interaction with MoS₂ monolayers in the absence of an electric field, but strongly interacts with MoS₂ monolayers when an electric field of 0.004 a.u. is applied. Moreover, the adsorbed CO₂ can be released from the surface of MoS₂ without any energy barrier once the electric field is turned off. Compared with the adsorption of CO₂, the interactions between N₂ and MoS₂ are not affected significantly by the external electric fields, which indicates that MoS₂ monolayers can be used as a robust absorbent for controllable capture of CO₂ by applying an electric field, especially to separate CO₂ from the post-combustion gas mixture where CO₂ and N₂ are the main components.