Luminescent carbon dots obtained from cellulose and their applications as sensors for metal ions

Abstract

Carbon dots (CDs) can be obtained from different sources including wastes and green biomass materials, which, together with the method of preparation, can contribute to reduce the cost of production of these nanomaterials.In this work we have prepared different CDs from cellulose and using hydrothermal carbonization. The obtained nanocarbons were functionalized to enhance the quantum yield (QY) by two different methods: in a one pot reaction where the CDs were obtained in the presence of certain amount of ammonia or through a reaction with a oligomeric poly(ethylene glycol) diamine (PEG1500 N) after the preparation of CDs. The obtained CDs were characterized by different techniques including Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), UV-VIS spectroscopy, Fluorescence, and Potentiometric Titration. Size distribution measurements from isolated nanoparticles showed that the different obtained CDs presented a narrow size distribution, with the diameters in the range 0.7–3.0 nm. The CDs which presented high values of QY were used as probes for different metal ions, showing considerable selectivity and sensitivity for Fe3+ ions and a limit of detection of 0.15 μM in the case of CDs modified with PEG1500 N oligomers.Finally, the results presented here show the possibility to obtain CDs with a relatively low cost method, using only water as solvent and with potential applications in different areas including those as probe for metal ions.