One-step hydrothermal method for preparing carbon dots and its determination of lead (II)

As a new type of carbon nanomaterials, carbon dots have attracted great interest due to their non-toxic, low preparation cost and unique photoluminescence properties. They have been widely studied and shown great potential in many fields. Here, nitrogen doped fluorescent carbon dots were prepared by one-step hydrothermal method using Epiphyllum leaves as raw materials. Ultraviolet-visible absorption spectrometer and fluorescence spectrometer were used to study the optical properties of carbon dots. The elemental composition and morphology of the surface of carbon dots were analyzed by transmission electron microscope, Fourier transform infrared spectroscopy and X-ray photoelectron spectrometer. The results show that the prepared carbon dots are uniformly dispersed in the aqueous solution, emit blue fluorescence, and the average particle size is 4.2 nm. The carbon dots have good light stability and strong anti-photobleaching ability. Continuous spectral scanning of the carbon dots can keep the fluorescence intensity basically unchanged within 30 minutes. In the concentration of 0∼f molL^-1 NaCl solution, the strength is not affected by the ionic strength. In the pH range of 4∼ 8, the fluorescence intensity of carbon dots is basically stable. The heavy metal ion pb²+ has a quenching effect on the fluorescence of carbon dots, and has a good linear relationship in the range of 0.5*200 μm. Therefore, a simple and green method for pb²+ has been developed.