Mxene nanosheet membranes for hydrogen isotope separation: An investigation via multi-scale molecular simulations

Abstract

Effective separation of hydrogen isotopes holds significant importance for scientific research, energy production, and the medical field. However, a challenge remains due to the similarity in the physicochemical properties of hydrogen isotopes. Currently, the research of hydrogen isotopes separation based on environmentally friendly and sustainable membranes is still in the blank field. Because of significantly reducing and optimizing experimental workload, high-throughput screening calculations combined with non-equilibrium dynamics simulations become an important tool for evaluating the newly designed materials for membranes. Among them, two-dimensional MXene, which have uniform pore size distribution and high permeability, were expected to separate hydrogen isotopes by membrane process. However, the large amount of MXene types troubled the experimental researchers from screening the optimal MXene. Herein, Monte Carlo combined with equilibrium molecular dynamics simulations was initially used for large-scale calculation to screen out ideal membrane candidates from 730 types of MXenes. Then, non-equilibrium molecular dynamics simulations were carried out on these candidates to explore the transport properties of gases in membranes under near-industrial conditions. The research indicated that a 4 Å interlayer spacing facilitated the effective separation of hydrogen isotopes. Ti_0.4Nb_1.6C with the lowest diffusion resistance, exhibited D₂/H₂ membrane selectivity that surpassed that of traditional processes. Therefore, it was recommended for further validation and application in experiments.