Synthesis of carbon quantum dots based on quinoa straw and their application in alkali metal ions detection

Carbon quantum dots (CQDs) with good water solubility and fluorescence properties were successfully synthesized from Chenopodium quinoa Willd. straw, a biomass by-product, by a one-step carbonization method. Structural characterization of the fabricated carbon quantum dots by Fourier transform infrared spectroscopy (FT-IR) demonstrated the presence of a large number of functional groups on the surface of the carbon quantum dots, which gives them good water solubility. The synthesized carbon quantum dots were characterized optically by ultraviolet-visible absorption spectroscopy (UV-Vis), photoluminescence spectroscopy (PL), and other analytical tools. Results indicate the addition of alkali metal ions gave a different degree of promotion of fluorescence intensity (Li+＞Cs+＞K+＞Na+＞Rb+), and according to this feature carbon quantum dots can be used as a new means of alkali metal ion detection.