An Electrochemical Sensor for Selective Detection of Cu2+ by using a self-Assembled Cu Coordinated β-cyclodextrin- nitrogen-Doped Carbon Quantum Dots Composite

Nitrogen-doped carbon quantum dots (N-CQDs) were synthesized by one-step hydrothermal method using citric acid as carbon source and urea as nitrogen source. β-cyclodextrin (β-CD) is a cyclic oligosaccharide with a unique hollow structure, which is beneficial to the enrichment of metal ions on the electrode surface while reducing the agglomeration of carbon quantum dots and maintaining conductivity. When Cu2+ is coordinated with β-CD, it can further increase the affinity for Cu2+ and recognize Cu2+ more sensitively. Therefore, we coordinated Cu2+ and β-CD to form copper ion coordinated β-cyclodextrin (Cu-β-CD). By self-assembly, the prepared N-CQDs and Cu-β-CD combined to form Cu-β-CD/N-CQDs composites. The electrochemical sensor constructed by Cu-β-Cd/N-CQDs successfully realizes the selective detection of Cu2+ in the range of 1–125 μmol l−1, and the lowest detection limit is 0.094 μmol l−1. In the detection of actual water samples, the Recovery of Cu2+ was between 92% and 120%, and the RSD was between 2.3% and 5.2%. Therefore, Cu-β-CD/N-CQDs composite is expected to be constructed as a non-toxic, pollution-free electrochemical sensor for selective detection of heavy metal Cu2+ ions in water.