Synthesis of quantum carbon dots (CQDs) from hard walnut skin by hydrothermal method

In this study biocompatible carbon quantum dots (CQDs) were prepared in a single step by hydrothermal method from walnut skin as a carbon source. Particle size, surface chemistry and crystal structure of carbon quantum dots were investigated using FTIR, DLS and XRD analyzes and optical properties of the material were investigated using absorption and fluorescence analyzes. The results showed that the quantum dots of synthesized carbon had a good particle size distribution and the average particle size was 5.7 ± 2.5. Also, the effect of temperature on initial carbonization was investigated, which with increasing the temperature of pyrolysis furnace, the percentage of carbon also increased, which was 46% by weight at 150 ° C and 83% by weight at 450 ° C. . Due to the fact t the difference in weight of carbon produced between temperatures of 350 and 450 degrees is very small, and considering the increase of 100 degrees, the temperature of 350 degrees was considered as a suitable temperature for the initial carbonization of walnut shell. The results of the absorption spectrum and fluorescence show that at the 238 wavelength an absorption peak of the sample is observed and the sample shows a good fluorescence scattering at the wavelength of 402 nm.According to the results of the studied FT-IR spectrum, the quantum surface of carbon dots is covered by hydrophilic functional groups such as hydroxyl, carbonyl and amine groups, and based on this, the synthesized nanoparticles are expected to show high dispersion in water.