Carbon quantum dots (CQDs) have attracted growing interest due to their tunable photoluminescence, low toxicity, and potential for low-cost production from abundant carbon-rich resources. A recent trend in CQD research involves the use of biomass-derived carbon precursors. In this study, multicolor CQDs were synthesized from sulfonated lignin via a solvent- and precursor-controlled hydrothermal/solvothermal approach. By varying the solvent type, precursor carbonization state, and nitrogenous additives, CQDs emitting blue, green, and orange fluorescence were successfully obtained. Structural and spectroscopic analyses revealed that surface functionalities and the degree of graphitization predominantly governed the emission color.
Kawasaki et al. (Mon,) studied this question.