Green synthesis of carboxymethyl cellulose-derived carbon quantum dots using microplasma technology

• CMC-derived CQDs (QCMC) were synthesized using a microplasma-assisted method. • QCMC showed high uniformity with a mean particle size of 1.3 nm. • Blue-shifted fluorescence was observed with increased alkaline fragmentation. • Plasma-induced synthesis, low-temperature carbonization under ambient air. • The method offers scalable synthesis of CQDs from sustainable precursors. Carbon quantum dots (CQDs) are promising nanomaterials known for their exceptional optical and electronic properties, making them ideal candidates for quantum dot-based devices. In this study, carboxymethyl cellulose (CMC) as a biomass-derived precursor, was utilized to synthesize CQDs (QCMC) through a microplasma-assisted approach under atmospheric pressure. The influence of plasma generating and NaOH concentration (0–0.5 M) on the hydrolysis, depolymerization, and carbonization processes of CMC was systematically investigated. The UV–Vis, FTIR, fluorescence, and TEM characterization confirmed the successful synthesis of QCMC. The results indicated that increasing NaOH concentration in microplasma synthesis facilitated the reduced particle size and formation of carboxyl functional groups through sequential hydrolysis, depolymerization, carbonization, and formation processes. These QCMC featured surface-enriched carboxyl functional groups. Specifically, QCMC synthesized from a 0.5 M NaOH solution demonstrated an average particle size of 1.3 nm within 60 min of reaction by notable fluorescence intensity and a blue shift with the maximum emission wavelength at 418 nm. This study highlights the potential of microplasma technology as an efficient, green synthesis method for producing CQDs with tunable properties for various applications.