Bimetallic Ag/Zn-ZIF-8: An efficient and sensitive probe for Fe3+ and Cu2+ detection

In this work, a series of bimetallic Ag/Zn-ZIF-8 materials were successfully developed for sensing toward traces of Fe3+ and Cu2+. 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 Fe3+, 6.7 μM for Cu2+ 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 Cu2+ and Fe3+, 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 Fe3+ than Cu2+.