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Electrical field facilitates selective transport of CO₂ through a laminated MoS₂ supported ionic liquid membrane

Ying, Wen, Hou, Quangang, Chen, Danke, Guo, Yi, Li, Zhuoyi, Zhang, Jun, Yan, Youguo, Peng, Xinsheng
Journal of materials chemistry A 2019 v.7 no.16 pp. 10041-10046
carbon dioxide, electric field, hydrogen, ionic liquids, ions, liquid membranes, methane, molybdenum disulfide, nanopores, nanosheets, nitrogen, solubility
Ionic liquid (IL), a neutral assembly of charged ions, is a potential material for CO₂ capture and storage. The practicality of IL can be improved by confining it into porous substrates and nanopores, which will further enhance the performance of IL by changing its structure. Additionally, an external electric field (EEF) should also influence the IL structure through its charged components. In this work, we applied an EEF on a MoS₂ supported ionic liquid membrane (MoS₂-SILM) to selectively facilitate CO₂ transport by the dual influence of MoS₂ nanochannel and EEF. The redistribution of nanoconfined IL under an EEF resulted in the increase in free volume of IL and decrease in anion–cation interactions, which led to the enhancement of CO₂ solubility and diffusion, and further, the permeance. Compared with the MoS₂-SILM without an EEF, the CO₂ permeance was enhanced from 89 GPU to 200 GPU, and the selectivity of CO₂/H₂, CO₂/CH₄ and CO₂/N₂ was also enlarged 2–3 times. An interesting phenomenon was the asymmetric CO₂ separation performance influenced by the CO₂ adsorbed on MoS₂ nanosheets under a positive and negative EEF, which may establish a new strategy to design high-performance gas separation membranes.