Green synthesis of High-Yield red fluorescent carbon dots from Amaranth for sensitive water detection in organic solvents

With the increasing demand for eco-friendly materials, the green synthesis of carbon dots (CDs) from natural sources has gained significant attention for applications in sensing and imaging. This study introduces a novel solvothermal method to synthesize high-yield red fluorescent CDs (R-CDs) from Amaranth, a sustainable and low-cost vegetable. The resulting R-CDs exhibit a remarkable quantum yield of 42.0 %, surpassing the performance of CDs derived from other natural sources. Characterization revealed a graphene core with surface functional groups such as –OH, –COOH, and –NH 2 . The R-CDs display excitation wavelength-independent emission at 601 nm and excellent stability under various environmental conditions. They were applied as a probe for detecting trace water in organic solvents, demonstrating high sensitivity, a broad linear detection range, and a low detection limit of approximately 5 ppm, attributed to the low solubility of CDs in water. This work underscores the potential of R-CDs as stable and efficient optical materials for environmental sensing, particularly in detecting water content in organic solvents, with broader implications for quality control in chemical and fuel industries.