Nitrogen‐Doped Bifunctional Carbon Dots: Photoluminescence Investigation, and Fluorescent Recognition Applications

Abstract In this work, three kinds of bifunctional carbon dots fluorescent sensor a‐CDs, b‐CDs and c‐CDs were prepared using 2,2‐di(prop‐2‐yn‐1‐yl)malonic acid as substrate, which are rich in carboxylic acid and conjugated structure. The morphology, chemical composition and optical properties of the prepared carbon quantum dots were characterized by transmission electron microscopy (TEM), X‐ray Photoelectron spectroscopy (XPS), FTIR, X‐ray diffraction (XRD), UV‐vis spectroscopy and fluorescence (FL). They display excellent water solubility, thermal stability and salt resistance, and overcomes the loss of optical activity in the dry state, which have been applied to the detection of aqueous metal ions and anions. Among them, the fluorescence quenching of Hg 2+ and Cu 2+ by a‐CDs and b‐CDs is obvious, which can be used as a highly sensitive dual ion sensor. At the same time, it has a good recognition and detection effect on 0–12 ppm ClO − or MnO 4 − , and the detection limits are as low as 0.1209 ppm and 0.0574 ppm, respectively. In addition, chiral c‐CDs can specifically recognize Hg 2+ , and the synergistic effect of c‐CDs and Hg 2+ can improve the recognition of chiral enantiomers.