A novel dual emission ratiometric fluorescence sensor Eu3+/CDs@UiO-66 to achieve Cu2+ detection in water environment

A novel dual-emission ratiometric fluorescent sensor Eu3+/CDs@UiO-66 was synthesized by post-synthesis modifying of UiO-66, a zirconium-based MOF formed by 1,4-phthalic acid (PTA) and Zr4+ , with europium ion (Eu3+) and carbon dots (CDs) and utilized for the determination of Cu2+ ions. The prepared composites not only maintain the excellent optical properties of CDs and Eu3+ but also have good stability in an aqueous solution. At the excitation wavelength of 299 nm, Eu3+/CDs@UiO-66 has two distinct emission peaks at 394 nm and 615 nm, respectively. More interestingly, when the material was dispersed in an aqueous solution containing Cu2+ ions, the characteristic peak of Eu3+ at 615 nm decreased significantly, while the characteristic peak of CDs at 394 nm remained unchanged. In the range of 0–500 μM, the relative fluorescence intensity ratio (F394/F615) linearly increased with increasing Cu2+ ion concentration, and the detection limit was calculated to be 51 nM (3Sb/Ksv). At the same time, the material can also be effectively applied to the detection of Cu2+ in environmental water samples. So Eu3+/CDs@UiO-66 can be developed as a potential ratiometric fluorescent sensor to detect Cu2+ ions.