CO2 capture and separation with metalloporphyrin nanosheets in an electric field: A DFT study

• An applied electric field can enhance the adsorption of CO 2 on M-N-C nanosheets. • CO 2 capture/separation can be achieved by switching on/off the applied electric field. • The selectivity of M-N-C to CO 2 in CO 2 /CH 4 /H 2 gas mixture can be improved under an applied electric field. Human activities are accelerating CO 2 emissions all over the world, leading to global warming. Absorbing CO 2 by controllable, reversible and selective sorbents can achieve both environmental protection and resource recovery. Therefore, in this work, for the first time, the capture of CO 2 by metalloporphyrin nanosheets (M-N-C, M = Fe, Co and Ni) in an electric field of 0-0.040 a.u. was studied by using density functional theory. Results showed that the interaction between metalloporphyrin nanosheets and CO 2 increased with the increase of the applied electric field, and the adsorption of CO 2 by Fe-N-C and Co-N-C nanosheets transformed from physical to chemical adsorption in the range of 0.020-0.025 a.u.. Fe-N-C and Co-N-C were better electric field modulated CO 2 capture materials. Therefore, the capture and release of CO 2 from Fe-N-C and Co-N-C nanosheets by switching on/off the applied electric field and the thermodynamics of CO 2 adsorption were discussed. More interestingly, at 0.030 a.u., the Fe-N-C and Co-N-C nanosheets can separate CO 2 efficiently from the CH 4 /H 2 /CO 2 mixture gases. These theoretical findings could provide useful guidance in the search for high quality CO 2 capture materials.