Greenish-blue fluorescent N, S - co-doped carbon dots derived from biomass for Cu2+ sensing

Biomass-derived carbon dots (BCDs) have evolved into eco-friendly sensors, reducing environmental and economic inconveniences. In this study, the nitrogen (N)- and sulfur (S)-co-doped carbon dots (NS-BCDs) were developed via a simple and facile hydrothermal process by utilizing Codiaeum variegatum as a green carbon precursor and thiourea as N and S dopants. The obtained NS-BCDs displayed greenish-blue fluorescence under 365 nm UV light irradiation. Several characterization techniques such as XRD, FTIR, HR-TEM, Zeta potential, DLS, and XPS were performed to confirm their size, elemental composition, charge, and the presence of various functional groups. The developed NS-BCDs are employed for selective fluorometric detection of copper ions (Cu 2+ ) through a static quenching mechanism. The limit of detection (LOD) of Cu 2+ is determined to be 0.82 µM with a linear range of 0–60 µM. Furthermore, the NS-BCDs are utilized as nanoprobes for detection of Cu 2+ in real water samples such as tap and river water. The present work demonstrates a facile and eco-friendly strategy for the synthesis of NS-BCDs from natural plant-derived precursors, revealing their remarkable optical properties and considerable promise for applications in fluorescent sensing and sensitive detection of Cu 2+ .