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 Cu2+, Pb2+ and Cd2+, which was based on NH2-MIL-88(Fe)-rGO composite modified glass carbon electrode (NH2-MIL-88(Fe)-rGO/GCE). The NH2-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 Cu2 +, Pb2+ and Cd2+ ions on the NH2-MIL-88(Fe)-rGO/GCE were explored by differential pulse anodic stripping voltammetry (DPASV). It was found that NH2-MIL-88(Fe)-rGO was capable of adsorbing Cu2+, Pb2+ and Cd2+ ions from aqueous solutions and the NH2-MIL-88(Fe)-rGO/GCE could enhance the electrochemical responses of Cu2+, Pb2+ and Cd2+ effectively. Important operational parameters such as electrolyte pH and deposition time were investigated and optimized for the determination of trace Cu2+, Pb2+ and Cd2+ ions. Under the optimum conditions, the proposed electrochemical sensor had a linear range of 0.005-0.3 mu M for Cd2+, 0.01-0.3 mu M for Pb2+ and 0.005-0.05 mu M for Cu2+, respectively. The limits of detection (LODs) are 4.9 nM for Cd2+, 10 nM for Pb2+ and 3.6 nM for Cu2+, 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.