▎ 摘　　要

NOVELTY - Preparing green-fluorescence emitting carbon quantum dots (CQDs) from a carbon source, where the source is Cissus quadrangularis, a traditional medicinal plant, involves collecting the stem and leaf parts of Cissus quadrangularis plant followed by thorough rinsing in water, and chopping the stem and leaf sections into chunks and crush in a household juice mixer to obtain the juice. The juice is filtered with Whatman qualitative filter paper to remove fibrous impurities. The juice is mixed with 99.9% pure ethylenediamine (EDA) solution in a 3:7 (v/v) ratio, and sonicated the mixture at room temperature for about 10 minutes. The mixture is put in a 50 ml Teflon-lined stainless steel autoclave for solvothermal synthesis. The solvothermal procedure is repeated at temperatures ranging from 150-220℃ for times ranging from 1-12 hours, until the pale yellow color solution is achieved. USE - Method for preparing green-fluorescence emitting carbon quantum dots from carbon source used for quantum dot-based display devices (claimed). ADVANTAGE - The formed carbon quantum dots have excellent solubility in water and also in various polar and nonpolar solvents, and are useful in cost-effective production of quantum dot-based display devices. DETAILED DESCRIPTION - Preparing green-fluorescence emitting carbon quantum dots (CQDs) from a carbon source, where the source is Cissus quadrangularis, a traditional medicinal plant, involves collecting the stem and leaf parts of Cissus quadrangularis plant followed by thorough rinsing in water, and chopping the stem and leaf sections into chunks and crush in a household juice mixer to obtain the juice. The juice is filtered with Whatman qualitative filter paper to remove fibrous impurities. The juice is mixed with 99.9% pure ethylenediamine (EDA) solution in a 3:7 (v/v) ratio, and sonicated the mixture at room temperature for about 10 minutes. The mixture is put in a 50 ml Teflon-lined stainless steel autoclave for solvothermal synthesis. The solvothermal procedure is repeated at temperatures ranging from 150-220℃ for times ranging from 1-12 hours, until the pale yellow colour solution is achieved. The as-synthesized solution is centrifuged for 15 minutes at 20 revolutions/minute after being cooled to room temperature. The contaminants settled down after centrifugation, and the supernatant solution is recovered. The supernatant solution filtered through a 0.22 µm syringe filter (polytetrafluoroethylene membrane) to eliminate any remaining contaminants not removed by centrifugation, and concentrated the solution using lyophilizer (-400℃) and stored for future use.