Terbium alginate encapsulated CsPbI3@Pb-MOF: a ratiometric fluorescent bead for detection and adsorption of Fe3.

ABSTRACT

Halide perovskite nanocrystals are innovative luminescent materials for fluorescent probes with high quantum yield and narrow emission bandwidth. However, the limited stability, single-signal response, and separation challenges obstruct their widespread use in water ion detection. Herein, a ratiometric fluorescence sensor based on terbium alginate gel beads (green fluorescent, namely Tb-AG) embedded with powdered CsPbI3@Pb-MOF (red fluorescent) was prepared for fluorescent determination and adsorption of Fe3+. Pb-MOF's protection notably enhances the water stability of CsPbI3, while the energy transfer between CsPbI3@Pb-MOF and Tb3+ elevates the optical performance of CsPbI3@Pb-MOF@Tb-AG. Significantly, Fe3+ markedly suppresses CsPbI3@Pb-MOF red fluorescence at 647 nm, while not noticeably affecting Tb-AG green emission at 528 nm. The sensor exhibited a strong linear response to Fe3+ concentrations ranging from 0 to 90 µM, with a detection limit of 0.44 µM and high selectivity. The CsPbI3@Pb-MOF@Tb-AG-based sensor has been effectively validated through its successful use in detecting Fe3+ in tap and river water samples. Furthermore, CsPbI3@Pb-MOF@Tb-AG demonstrates a notable adsorption capacity of 325.4 mg g-1 Fe3+. Finally, the mechanism of Fe3+ detection and adsorption was determined.