▎ 摘　　要

A carbon quantum dot (CQD)/reduced graphene oxide (rGO) nanocomposite modified glassy carbon electrode (GCE) was developed as a novel system for electrochemical detection of cadmium ion (Cd). The characterization of the synthesized CQD/rGO nanocomposite was done by Fourier transform infrared, high-resolution transmission electron microscopy, Raman, ultraviolet-visible, and X-ray diffraction analyses. The blending of CQD and rGO provides the sensor with a large surface area, high selectivity, sensitivity, stability, and excellent electrochemical compatibility. The modified CQD/rGO/GCE gives a linear response for Cd ion from 0.5 to 9 nM with a recognition limit of 0.3 nM. Over the studied scan rate, the composite exhibited a diffusion-controlled behavior. The modified electrode showed a good selectivity against interfering species (e.g., Zn2+, Ba2+, Bi2+, Hg2+, Cr3+, Pb2+, Ca2+, Ni2+, Mg2+, and Cu2+) with good reproducibility. This proposed detection system was proved to be cost-effective, precise, and easy to apply for environment monitoring such as groundwater, river water, and industrial effluents.