Nickel(II) ion-intercalated MXene membranes for enhanced H2/CO2 separation

Hydrogen fuel has been embraced as a potential long-term solution to the growing demand for clean energy. A membrane-assisted separation is promising in producing high-purity H 2 . Molecular sieving membranes (MSMs) are endowed with high gas selectivity and permeability because their well-defined micropores can facilitate molecular exclusion, diffusion, and adsorption. In this work, MXene nanosheets intercalated with Ni 2+ were assembled to form an MSM supported on Al 2 O 3 hollow fiber via a vacuum-assisted filtration and drying process. The prepared membranes showed excellent H 2 /CO 2 mixture separation performance at room temperature. Separation factor reached 615 with a hydrogen permeance of 8.35 × 10 −8 mol·m −2 ·s −1 ·Pa −1 . Compared with the original Ti 3 C 2 T x /Al 2 O 3 hollow fiber membranes, the permeation of hydrogen through the Ni 2+ -Ti 3 C 2 T x /Al 2 O 3 membrane was considerably increased, stemming from the strong interaction between the negatively charged MXene nanosheets and Ni 2+ . The interlayer spacing of MSMs was tuned by Ni 2+ . During 200-hour testing, the resultant membrane maintained an excellent gas separation without any substantial performance decline. Our results indicate that the Ni 2+ tailored Ti 3 C 2 T x /Al 2 O 3 hollow fiber membranes can inspire promising industrial applications.