Simultaneous stripping determination of cadmium and lead ions based on the N-doped carbon quantum dots-graphene oxide hybrid

Abstract In the present work, a new electrochemical sensor using anodic stripping voltammetry from N-doped carbon quantum dots-graphene oxide hybrid (NCQDs-GO) for the simultaneous determination of cadmium ion (Cd 2+ ) and lead ion (Pb 2+ ) is developed. In the hybrid, both the NCQDs and GO have large electroactive surface areas and abundant oxygen-containing functional groups, which supply active sites for the efficient adsorption of heavy metal ions by electrostatic interaction to improve the sensor sensitivity. The NCQDs homogeneously distribute on the surface of GO and play an important role in re-oxidizing metals into ions for stripping analysis. Based on these excellent advantages, the electrochemical Cd 2+ and Pb 2+ sensor using a NCQDs-GO hybrid modified glassy carbon electrode (NCQDs-GO/GCE) exhibits superior analysis performance than those using just NCQDs on GCE (NCQDs/GCE) and just GO on GCE (GO/GCE), such as wide linear range (11.24–11241 μg/L for Cd 2+ and 20.72–10360 μg/L for Pb 2+ , respectively), low detection limit (7.45 μg/L for Cd 2+ and 1.17 μg/L for Pb 2+ , respectively), good reproducibility and selectivity. Moreover, satisfactory testing recoveries are obtained for the simultaneous detection of Cd 2+ and Pb 2+ in lake water and tap water, suggesting that NCQDs-GO hybrid is a promising material for the fabrication of electrochemical heavy metal ion sensor.