Construction of NaYF4:Eu@carbon dots nanocomposites for multifunctional applications

The combination of carbon dots (CDs) and rare-earth ions has attracted increasing attention due to their unique fluorescence properties. Herein, CDs are incorporated with NaYF 4 :Eu to form stable NaYF 4 :Eu@CDs nanocomposites by a simple sol-gel route. It has been demonstrated that CDs are successfully embedded in the silica layer outside NaYF 4 :Eu nanoparticles. These nanocomposites exhibit characteristic emissions of both CDs and NaYF 4 :Eu under a single excitation wavelength. By using their dual-emissive properties, the nanocomposites can act as ratiometric fluorescent sensor for selective detection of Fe 3+ ions in the range of 0–350 μM. The temperature-dependent luminescent property of the nanocomposites makes them also suitable as thermometers in the range from 377 to 467 K. In addition, the luminescent color can be regularly adjusted by tuning the mass ratio of NaYF 4 :Eu to CDs. This combing strategy enables us to achieve dual emission of CDs and Eu 3+ ions in nanocrystals, opening an avenue towards multifunctional applications in widespread fields.