One-step green synthesized fluorescent carbon nanodots from bamboo leaves for copper(II) ion detection

• High quantum yield CQDs are synthesized with bamboo leaves as carbon source.
• BPEI-capped CQDs are prepared as luminescent probes for sensitive Cu2+ detection.
• Cu2+ in river water is successfully analyzed with BPEI-CQDs nanoprobe.

High quantum yield carbon quantum dots (CQDs) are successfully synthesized via a simple, low cost, and green hydrothermal method using bamboo leaves as carbon source for the first time. Branched polyethylenimine (BPEI)-capped CQDs (BPEI-CQDs) are prepared by coating the CQDs with BPEI via electrostatic adsorption. The BPEI-CQDs are then employed as fluorescent probes for sensitive and selective Cu2+ detection. Experimental results show that the synthesized CQDs have average size of 3.6 nm in diameter with narrow size distribution. The biomass-based CQDs offer high quantum yield of 7.1%. The BPEI-CQDs-based sensing system renders a simple, reliable and sensitive Cu2+detection with limit of detection (LOD) as low as 115 nM and a dynamic range from 0.333 to 66.6 μM. In addition, the BPEI-CQDs are successfully used to detect Cu2+ in river water, demonstrating its good selectivity and great potential for analysis of environmental water samples.