Bright blue emissions N-doped carbon dots from a single precursor and their application in the trace detection of Fe3+ and F−

Abstract

For the development of high-resolution optical detection of analytes, rapid and facile methods for the preparation of homogeneous carbon dots (CDs) with good fluorescence quantum yields (QY) are required. Herein, we report on the synthesis of N-doped CDs (N-CDs) using a single precursor (N-methyl-2-pyrrolidone, NMP); they have a good QY of up to 32.5%. The use of a single precursor results in homogenous N-CDs, and oxidation by H2O2 accelerates the reaction. The morphology and chemical constitution of the N-CDs were determined by atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS), and their formation mechanism is proposed based on the experimental observations. The fluorescence of N-CDs can be selectively quenched by Fe3+ ions and recovered by the addition of F−. Therefore, turn-off and turn-off-on fluorescence sensors were constructed for the high-sensitivity trace detection of Fe3+ and F−, respectively, and the sensing mechanism was investigated. Finally, for the simple and intuitive detection of Fe3+ and F−, we developed a fluorescent test paper that allows the instant detection of Fe3+ and F− by the naked eye.