Green synthesis of carbon dots from prawn shells for highly selective and sensitive detection of copper ions

•Carbon dots derived from prawn shells were successfully synthesized.•A simple, sensitive, selective and label free sensing of Cu2+ was developed.•The detection limit of developed method achieved 5nM.•The sensor system was demonstrated to detect Cu2+ in environmental water sample. A facile, economical and effective green method was developed for synthesis of fluorescent carbon dots (C-dots) from prawn shells. The results showed that these C-dots (with an average diameter of 4nm) possess many excellent features such as to eliminate blue fluorescence under UV light (λ=365nm), with high monodispersity, good stability, excellent water solubility and high quantum yield (9%). We further explored these C-dots as effective sensing probes for Cu2+ detection and found that they exhibit excellent selectivity and sensitivity toward Cu2+ with a low detection limit of 5nM. We further demonstrated this novel sensing platform on Cu2+ ions analysis from seawater samples. This method is extremely rapid, low cost, ecofriendly, highly selective and sensitive for Cu2+ ions sensing from various sources of environment such as drinking water, river water and sea water.