Synthesis Of Biomass Based Nitrogen Doped Carbon Quantum Dots And Its Fluorescence Properties

Carbon quantum dots is a new type of carbon nano-material, its particles is less than 10 nm, due to the unique excitation wavelength dependent fluorescent behavior, biocompatibility, low toxicity so on, carbon quantum dots has broad application prospects in fluorescence imaging, ion detection, biological sensing, and so on. Based on this, we conducted a series of study. With different materials as carbon precursor, we obtained nitrogen doped carbon quantum dots with superior performance by different preparation methods, and then explored their fluorescence properties, morphology, structure, application and so on, the main contents are as follows:In the first part, Cellulose was used as reaction material, with Solid phase pyrolysis method, nitrogen-doped fluorescent carbon quantum dots（N-CQDs1） were synthesized by carbonizing, pyrolysing cellulose under ammonia atmosphere. The effects of reaction time and temperature on the preparation of carbon quantum dots were discussed. As-prepared N-CQDs1 has good water solubility, excitation wavelength dependent fluorescent behavior, anti-light bleaching, p H stability. It is found that mercury ions can effectively quench the N-CQDs1, and show good selectivity towards Hg²⁺. N-CQDs1 as Hg²⁺ nano-probe, the detection limit is 7.7 nM, which is lower than the maximum level permitted by the US EPA10 nM.In the second part, we use Dioscorea opposite as carbon precursors, nitrogen-doped carbon quantum dots（N-CQDs2） was prepared by hydrothermal carbonization Dioscorea opposite adding saturated ammonium sulfate solution. The effects of different preparation conditions on the fluorescence properties of N-CQDs2 were investigated, when the conditions is 200 °C, 12 h, 15 g, N-CQDs2 has the best performance. At the same time, the application of N-CQDs2 in the anti-counterfeiting identification and fluorescent film were discussed.In this paper, the preparation method of nitrogen-doped carbon quantum dots has the characteristics of easy to get raw materials, low cost, easy to scale production, high carbonization degree, and the specific application fields. The preparation methods are rarely reported in the literature, and have a certain innovation, which has a certain reference value for the synthesis of carbon quantum dots.