Polypyrrole/zinc oxide/zeolitic imidazolate framework (PPy/ZnO/ZIF67) nanocomposites modified electrode for electrochemical analysis of Cd2+ and Pb2+ in waters

The electrochemical analysis of cadmium and lead ions was studied using a polypyrrole/zinc oxide/zeolitic imidazolate framework (PPy/ZnO/ZIF67) nanocomposite modified electrode in waters. Polypyrrole nanowires (PPy) were synthesised by chemical oxidation method and then zinc oxide (ZnO) was synthesized on it by hydrothermal method. The metal-organic framework material ZIF67 was prepared by solvothermal method in situ growing on PPy nanowires, which can improve the stability and electroconductivity of ZIF67, which were beneficial to increase the electrochemical active. The structure of the nanocomposites was characterized by transmission electron microscopy (TEM), Fourier transform infrared absorption spectroscopy (FTIR) and X-ray diffraction (XRD). In contrast, PPy/ZnO/ZIF67 has higher peak current and electrochemical properties. The peak current response of Cd2+ and Pb2+ detected by the PPy/ZnO/ZIF67 modified electrode showed a good fit in a wide range. The fabricated electrochemical sensor detects Cd2+ and Pb2+ individually and simultaneously. The limit of detection (LOD = 3σ/k) for the individual detection of Cd2+ and Pb2+ were 6.92 μg/L and 1.49 μg/L, respectively, with detection ranges from 20 μg/L to 3000 μg/L and 5 μg/L to 4000 μg/L. The selectivity and practicality of the PPy/ZnO/ZIF67 modified electrode were verified by the anti-interference experiment and the analysis of actual water samples.