Carbon quantum dots (CQDs) are a new category of carbon nanomaterials with dimensions less than 10 nm, which were obtained for the first time during the purification of singlewalled CNTs through primary electrophoresis in 2004 [1]. CQDs, as a new generation material with excellent electron transport capability, unique luminescence performance, smaller size, good solubility, biocompatibility, and less toxicity, are a suitable alternative to other carbon competitors synthesized by top-down and bottom-up methods [2]. The study aimed to green synthesize of carbon quantum dots from a native plant called Woad or Indigo with the scientific name Indigofera Tinctoria L. Woad is a medicinal-industrial plant belonging to the legume family, which is cultivated in the south of Iran (Shushtar). The components of Woad plant are: alkaloids, glycosides, flavonoids, tannins, and phenolic compounds, amino acids, carbohydrates, mineral compounds, other compounds such as ash, ash soluble in acid, ash soluble in water, etc. [3-4]. In this study, carbon quantum dot was synthesized by a hydrothermal method from Woad as precursors in deionized water at 200 °C for 14 h [5]. The sample was dried in an oil bath and washed three times with ethanol. Finally, the resulting black powder was dried in a vacuum oven for 6 hours. The quantum dot samples were characterized by a scanning transmission electron microscope (TEM). The corresponding chemical structure was characterized by ultraviolet-visible (UV-Vis), Fouriertransform infrared (FT-IR), and X-ray energy dispersive (EDX) spectroscopies. The study suggests that the obtained carbon quantum dot can be used in different applications, especially electrochemical or fluorescence sensors and separation.
