Determination of Trace Cd(II) in Water and Cosmetics based on Au/GO/CuO Nanocomposite Functionalized Electrochemical Sensor

Cadmium (Cd(II)) is highly toxic to environmental, and while many approaches have been developed to measure cumulative Cd(II) concentration over time, online monitoring of spatiotemporal changes remains challenging. To address this, an electrochemical sensor for determination of ultra-trace Cd(II) was developed, based on gold/graphene oxide/copper oxide (Au/GO/CuO) nanomaterials modifying glassy carbon electrode. CuO nanoparticles were prepared by a green synthesis method using plant extract, and the Au nanoparticles were deposited on the GO/CuO nanosubstrates by an in situ electrochemical method. The prepared nanocomposites were characterized by field-emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The CuO nanoparticles are layered flower-like with an average particle size of 200–500 nm. Au/GO/CuO nanocomposites with high specific surface area and excellent electronic transmission capability enhanced the electrochemical signal of the sensor. Owing to the synergistic effect of Au/GO/CuO, the sensor exhibited good performance to Cd(II) in the ultra-wide range of 5 × 10−11–5 × 10−7 M with a detection limit of 2 × 10−11 M. The sensor was successfully quantified for determining Cd(II) with desirable recovery, displaying outstanding long-term stability, high sensitivity, and reproducibility. After validating its accuracy, this sensor was successfully used for detection of Cd(II) in water and cosmetic samples.