Nitrogen-doped carbon dots with high quantum yield for colorimetric and fluorometric detection of ferric ions and in a fluorescent ink

Nitrogen-doped carbon dots (N-CDs) with a quantum yield of 413% and excellent stability were prepared and are shown to be viable probes for the determination of ferric ions, which is a strong quencher of fluorescence. The absorption peak of the N-CDs is located at325nm. The optimal excitation and emission wavelengths of the N-CDs are 340nm and 430nm, respectively. The fluorometric response to Fe(III) is linear in the ranges between 1.0 and 21.0M and between 0.05 and 30.0M, and the limits of detection are 0.28M in case of colorimetry and 13.5nM in case of fluorometry. Quenching by Fe(III) is mainly attributed to a combination of chelation (static quenching) and inner filter effect. The N-CDs also can be used as a new sort of fluorescent ink owing to the strong luminous performance and chemical inertness.