MIL-88B(Fe)-NH: an amine-functionalized metal-organic framework for application in a sensitive electrochemical sensor for Cd, Pb, and Cu ion detection.

We propose here an electrochemical platform for multi-heavy metal ion detection in water based on MIL-88B(Fe)-NH, an amine-functioned metal-organic framework (MOF) for modifying the surface of a glassy carbon electrode (GCE). Herein, MIL-88B(Fe)-NH with abundant functionalized amine groups can play the role of capture sites for the enrichment of metal ions before electrochemical oxidation sensing. MIL-88B(Fe)-NH was synthesized under optimized conditions through a solvothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. MIL-88B(Fe)-NH was then drop-casted on GCE to electrochemically determine the Cd, Pb and Cu ion concentrations by differential pulse voltammetry (DPV). The electrochemical sensor exhibits excellent electrochemical performance toward Cd, Pb and Cu ions in the large linear ranges of 0.025-1.000 μM, 0.3-10.0 μM and 0.6-10.0 μM with limits of detection that are 2.0 × 10 M, 1.92 × 10 M and 3.81 × 10 M, respectively. The fabricated sensor also shows high reliability and good selectivity. This MIL-88B(Fe)-NH application strategy is promising for the evaluation of various heavy metal ions in water.