Bimetallic engineering in Ag/Zn-ZIF-8/Pebax mixed matrix membranes for enhanced CO₂ separation

Mixed matrix membranes (MMMs) have emerged as a critical platform for molecular separation, especially carbon capture from point-emission sources. In this study, a series of novel MMMs were fabricated by incorporating the bimetallic Ag/Zn-ZIF-8 nanoparticles into the poly (ether-block-amide) (Pebax) matrix for efficient CO₂/N₂ separation. The SEM, EDS, XRD, FTIR, XPS, TGA, N₂ adsorption-desorption measurements were employed to elucidate the microstructures and physicochemical properties of the resultant nanoparticles and membranes. The bimetallic coordination-induced optimization modulated the inherent structure of ZIF-8 framework and enhanced CO₂ affinity, thereby forming the CO₂-selective transport channels over N₂. The incorporation of Ag ⁺ promoted the uniform dispersion of Ag/Zn-ZIF-8 nanoparticles in Pebax matrix, indicating the excellent polymer-filler interfacial compatibility. Impressively, the resulting membrane achieved the superior separation performance with a CO₂ permeability of 359 Barrer and a CO₂/N₂ selectivity of 53, which were 2.5 and 1.4 times higher than that of the pristine Pebax membrane. Besides, the introduction of Ag/Zn-ZIF-8 nanoparticles enhanced the thermal and mechanical stability of the membrane, ensuring the potential for long-term operation. These findings herein advance the rational design and preparation of high-performance MMMs for sustainable carbon capture.