On the absorption and dialytic separation of gases by colloid septa

Abstract

Research on gas separation membrane has targeted upon maximizing the selectivity and permeance. The development of 2D materials (e.g., MXene) gives a novel avenue to surpass the “trade-off” among the membrane selectivity and permeability. However, randomly stacked nanosheets and the regulation of interlayer spacing for MXene nanosheets hinder the development of MXene membrane. To this end, we designed a Pd-intercalated lamellar MXene membrane to modify the surface chemical properties (H-spillover effect) of MXene (Ti3C2Tx) and to expand the interlayer spacing (from 2.29 to 3.26 Å) due to the strong interaction between Pd2+ and MXene nanosheets with negative charge. Here, we performed a single-step etching approach to prepare 2D Pd-MXene membrane and demonstrated its excellent H2 permeability of 2.66 × 10−7 mol m−2 s−1·Pa−1 and H2/CO2 selectivity of 242 at 25 °C, which greatly exceeds the current benchmark membranes. We also developed single gas transport mathematical mechanism models to interpret and support the experimental results. The combined experimental and modeling results show that interlayer spacing and H-spillover effect of Pd-MXene membrane benefit H2/CO2 separation.