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 Ni2+ were assembled to form an MSM supported on Al2O3 hollow fiber via a vacuum-assisted filtration and drying process. The prepared membranes showed excellent H-2/CO2 mixture separation performance at room temperature. Separation factor reached 615 with a hydrogen permeance of 8.35 x 10(-8) mol center dot m(-2)xs(-1)xPa(-1). Compared with the original Ti3C2Tx/Al2O3 hollow fiber membranes, the permeation of hydrogen through the Ni2+-Ti3C2Tx/Al2O3 membrane was considerably increased, stemming from the strong interaction between the negatively charged MXene nanosheets and Ni2+. The interlayer spacing of MSMs was tuned by Ni2+. During 200-hour testing, the resultant membrane maintained an excellent gas separation without any substantial performance decline. Our results indicate that the Ni2+ tailored Ti3C2Tx/Al2O3 hollow fiber membranes can inspire promising industrial applications.