Authors: Vanesa Romero,Victoria Vila, Inmaculada de la Calle, Isela Lavilla, Carlos Bendicho
Journal: Sensors and Actuators B: Chemical, Vol. 280, 2019, pp. 290-297
In this work, a novel one–step ‘bottom–up’ synthetic approach is described for obtaining highly fluorescent nitrogen (N) and sulphur (S) co–doped carbon dots (CDs) following photochemical oxidation of carbohydrates naturally occurring in vegetables. N and S co–doping allows more active sites in the CDs surface resulting in an enhancement of their luminescent properties. Among the 18 vegetables studied as green precursors of CDs, those rich in proteins and glucosinolates (natural S–linked glucosides), such as cruciferous vegetables (Brassicaceae family), i.e. broccoli, cauliflower and Romanesco, facilitate an efficient N and S co–doping of the CDs during the photochemical reaction without the need for further post–synthetic treatments. A comprehensive characterization of CDs obtained from broccoli was performed by transmission electron microscopy, elemental analysis, X–ray fluorescence (total reflection), UV–Vis absorption and Fourier transform–infrared spectroscopy. Quantum yields and fluorescence up–conversion properties were also investigated.