Highly efficient detection of Cd(Ⅱ) ions in water by graphitic carbon nitride and tin dioxide nanoparticles modified glassy carbon electrode

In this work, we developed a novel electrochemical sensor modified with graphitic carbon nitride (g-C3N4) and tin dioxide nanoparticles (SnO2 NPs). The detection of Cd(II) ion in water environments was carried out using differential pulse anodic stripping voltammetry (DPASV) technique. Scanning electron microscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and contact angle analyses were used for electrode characterization. The experimental results show that the improved electrochemical activity is due to the large specific surface area and hydrophilic functional groups of g-C3N4, which improves the hydrophilicity of the electrode and the adsorption of Cd(II) ions. Meanwhile, SnO2 has excellent electrocatalytic performance, which enhances the free electron transfer efficiency. The combination of these two modified compositions can synergistically improve the electrode sensitivity, and enhance the response speed of the detection process. Under the optimal detection conditions, the sensor achieves a wide linear range (0.05–100 μg L−1) and a lower detection limit (0.16 μg L−1), with good anti-interference performance and stability. This sensor has also been successfully applied to detect Cd(II) ions in tap water and groundwater. Our findings provide a promising method for sensitive, rapid, and in situ monitoring of Cd(II) ions in aqueous environments.