Upconversion nanoparticles/carbon dots (UCNPs@CDs) composite for simultaneous detection and speciation of divalent and trivalent iron ions

In this study, the application of carbon dots (CDs) modified NaYF4:Yb, Er nanoparticles ([email protected]) as the fluorescent nanoprobe for simultaneous detection of Fe2+ and Fe3+ was investigated. Fe3+ quantification (5–80 μmol L−1) was achieved, as a result of Fe3+ induced fluorescence quenching of [email protected] at 434 nm (under the 336 nm excitation). The chelate (Fe2+-phen) formed by Fe2+ and 1,10-phenanthroline had a broad absorption centered at 510 nm, due to inner filter effect (IFE), Fe2+ quantification (4–120 μmol L−1) was achieved as a result of (Fe2+-phen) induced fluorescence quenching of [email protected] at 545 nm (under the 980 nm excitation). The resultant [email protected] probe, with excellent anti-interference capability, favorable fluorescence stability, and convincing performance in real sample analysis, showed promising application in simultaneous detection of Fe2+ and Fe3+.