In this work, a series of bimetallic Ag/Zn-ZIF-8 materials were successfully developed for sensing toward traces of Fe 3+ and Cu 2+ . The bimetallic Ag/Zn-ZIF-8 was synthesized via a one-pot method. Interestingly, this obtained bimetal Ag/Zn-ZIF-8 exhibited high photoluminescence property and excellent fluorescence quenching response to target analytes with high selectivity , sensitivity and detection limits of 3.9 μM for Fe 3+ , 6.7 μM for Cu 2+ ions, respectively, both of which have been confirmed to be very comparable or better than the reported LMOFs sensors. The possible photoluminescence quenching mechanisms were studied in detail, revealing that the competitive absorption of excitation source and resonance energy transfer (RET) resulted from the host (imidazole of the framework, Lewis basic sites)-guest (metal ions of Cu 2+ and Fe 3+ , Lewis acid sites) interaction should be responsible for high efficiency fluorescence quenching. The binding energies of metal ions adsorption on the ZIF-8 obtained by DFT simulation were further performed to explain the higher quenching effect of Fe 3+ than Cu 2+ .
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 CO 2 /N 2 separation. The SEM, EDS, XRD, FTIR, XPS, TGA, N 2 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 CO 2 affinity, thereby forming the CO 2 -selective transport channels over N 2 . 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 CO 2 permeability of 359 Barrer and a CO 2 /N 2 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.
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