Carbon dots (CDs) are an emerging family of nanostructures due to their unique optical properties, high chemical stability, biocompatibility, and low toxicity, they have been able to attract a lot of attention and cause significant changes in various scientific fields. In this study, the green synthesis of stable CDs by hydrothermal and pyrolysis methods (H-CDs and P-CDs) is performed from Nigella sativa seeds as a natural precursor. Using these methods, the formation and the surface passivation of the CDs are done simultaneously, resulting in the intrinsic fluorescence emission. The as-prepared CDs are characterised by UV–vis spectroscopy, fluorescence spectroscopy, elemental analysis, dynamic light scattering, Fourier transform infrared spectroscopy, and transmission electron microscopy, from which their structural information and property are interpreted. The fluorescence intensity graph of H-CDs and P-CDs, with excitation wavelengths in 360 nm, shows the highest emissions at 430 and 410 nm, respectively. Particle size distribution was obtained at about 4 nm. The fluorescent quantum yield (QY) of H-CDs and P-CDs was measured to be 7% and 2%, respectively. The synthesised CDs showed good photoluminescence (PL) responses to acetone solution. Acetone had a different effect on the PL properties of CDs obtained from pyrolysis and hydrothermal methods so that in P-CDs, it increased the intensity of PL, and in H-CDs; it decreased the intensity of PL.

碳点（CDs）是一个新兴的纳米结构家族，由于其独特的光学性质、高化学稳定性、生物相容性和低毒性，它们已经能够引起很多关注并在各个科学领域引起重大变化。在这项研究中，通过水热和热解方法（H-CDs 和 P-CDs）从Nigella sativa进行了稳定 CDs 的绿色合成种子作为天然前体。使用这些方法，CD 的形成和表面钝化同时进行，从而产生固有的荧光发射。制备的CDs通过紫外-可见光谱、荧光光谱、元素分析、动态光散射、傅里叶变换红外光谱和透射电子显微镜进行表征，从中解释了它们的结构信息和性质。H-CDs 和 P-CDs 的荧光强度图，激发波长为 360 nm，分别显示在 430 和 410 nm 处的最高发射。在约 4 nm 处获得粒度分布。H-CDs 和 P-CDs 的荧光量子产率 (QY) 分别测量为 7% 和 2%。合成的 CD 对丙酮溶液显示出良好的光致发光 (PL) 响应。丙酮对热解法和水热法获得的CDs的PL性质有不同的影响，因此在P-CDs中，它增加了PL的强度，而在H-CDs中；它降低了PL的强度。