A Novel Dual-Emission Fluorescence Probe Based on CDs and Eu(3+) Functionalized UiO-66-(COOH)(2) Hybrid for Visual Monitoring of Cu(2+)

In this work, CDs@Eu-UiO-66(COOH)(2) (denoted as CDs-F2), a fluorescent material made up of carbon dots (CDs) and a Eu(3+) functionalized metal–organic framework, has been designed and prepared via a post-synthetic modification method. The synthesized CDs-F2 presents dual emissions at 410 nm and 615 nm, which can effectively avoid environmental interference. CDs-F2 exhibits outstanding selectivity, great sensitivity, and good anti-interference for ratiometric sensing Cu(2+) in water. The linear range is 0–200 µM and the limit of detection is 0.409 µM. Interestingly, the CDs-F2’s silicon plate achieves rapid and selective detection of Cu(2+). The change in fluorescence color can be observed by the naked eye. These results reveal that the CDs-F2 hybrid can be employed as a simple, rapid, and sensitive fluorescent probe to detect Cu(2+). Moreover, the possible sensing mechanism of this dual-emission fluorescent probe is discussed in detail.