Highly photoluminescent nitrogen-rich carbon dots from melamine and citric acid for the selective detection of iron(III) ion

A facile one-step hydrothermal strategy to fabricate nitrogen-rich carbon dots (N-rich CDs) with melamine and citric acid as the precursors has been successfully developed. The as-prepared N-rich CDs exhibit a uniform quasi-spherical morphology, high N content of about 24 wt% and very strong photoluminescence (PL) with a high quantum yield of ∼42%. Additionally, the PL emission of these N-rich CDs can be stabilized in a wide pH range from 4.0 to 11.0. More importantly, the N-rich CDs can be utilized as the label-free PL sensors for the highly selective and sensitive detection of Fe3+ ions in aqueous solution with a very low detection limit of 142 nM.