Electrochemical sensor using NH2-MIL-88(Fe)-rGO composite for trace Cd2 +, Pb2 +, and Cu2 + detection

A novel electrochemical sensor was developed for the sensitive and selective detection of Cu 2   + , Pb 2   + and Cd 2   + , which was based on NH 2 -MIL-88(Fe)-rGO composite modified glass carbon electrode (NH 2 -MIL-88(Fe)-rGO/GCE). The NH 2 -MIL-88(Fe)-rGO composite was facilely prepared by a one-step method and characterized by SEM, XRD, Raman spectrum and electrochemical methods. The stepwise GCE modified process was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical behaviors of Cu 2   + , Pb 2   + and Cd 2   + ions on the NH 2 -MIL-88(Fe)-rGO/GCE were explored by differential pulse anodic stripping voltammetry (DPASV). It was found that NH 2 -MIL-88(Fe)-rGO was capable of adsorbing Cu 2   + , Pb 2   + and Cd 2   + ions from aqueous solutions and the NH 2 -MIL-88(Fe)-rGO/GCE could enhance the electrochemical responses of Cu 2   + , Pb 2   + and Cd 2   + effectively. Important operational parameters such as electrolyte pH and deposition time were investigated and optimized for the determination of trace Cu 2   + , Pb 2   + and Cd 2   + ions. Under the optimum conditions, the proposed electrochemical sensor had a linear range of 0.005––0.3   μM for Cd 2   + , 0.01–0.3   μM for Pb 2   + and 0.005–0.05   μM for Cu 2   + , respectively. The limits of detection (LODs) are 4.9   nM for Cd 2   + , 10   nM for Pb 2   + and 3.6   nM for Cu 2   + , respectively. The proposed method has been successfully applied to determine three metal ions in water samples. The developed sensor promises simple preparation, fast operation, good sensitivity and excellent reusability, showing great potential for monitoring of water quality.