Revolutionary insights into CO2 solubility in nanoporous MXenes: Atomic- Scale revelations in CO2/CH4 separation and permeance optimization

QK Yin and MH Wang and CF Xia and ZJ Wang and SY Liu and W Lyu and B Liao and Z Sun and BJ Wei and XQ Lu, MATERIALS TODAY PHYSICS, 57, 101802 (2025).

DOI: 10.1016/j.mtphys.2025.101802

CO2 solubility strongly influences permeance based on the solubility- diffusion mechanism, making the identification of key factors affecting CO2 solubility crucial for the advancement of gas separation technologies. Here, we explore the dominant factors in regulating CO2 solubility in 2D nanoporous M2CO2 (M = Sc, Ti, V, Cr, Y, Zr, Nb, Mo) using molecular dynamics simulation. Specifically, the revolutionary insight to systematically investigate the sequential interplay among CO2-membrane interactions, CO2 solubility, and atomic-scale factors in this specific type of nanoporous MXene. The results show that nanoporous Nb2CO2 achieves 100 % CO2/CH4 selectivity and Y2CO2 possesses a CO2 permeance of 1.95 x 10-4 mol/s center dot m2 Pa. The pore limited diameter of 2D nanoporous M2CO2 influences the mean free path for CO2 diffusion, whereas the CO2-membrane interaction is the pivotal factor in tuning CO2 solubility. The nanopore of Y-doped in Nb2CO2 enhances CO2 solubility showing a significant improvement in CO2 solubility and permeance (7.88 x 107 mol/m4 center dot Pa and 1.04 x 10-4 mol/s center dot m2 Pa). The results of this work reveal that metal atoms within the nanopore are the main reason for affecting solubility, which provides theoretical guidance for the application of nanoporous MXene in CO2 separation.

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