MIL-88B(Fe)-NH2: an amine-functionalized metal–organic framework for application in a sensitive electrochemical sensor for Cd2+, Pb2+, and Cu2+ ion detection

Abstract

We propose here an electrochemical platform for multi-heavy metal ion detection in water based on MIL-88B(Fe)-NH₂, an amine-functioned metal–organic framework (MOF) for modifying the surface of a glassy carbon electrode (GCE). Herein, MIL-88B(Fe)-NH₂ 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)-NH₂ 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)-NH₂ was then drop-casted on GCE to electrochemically determine the Cd²⁺, Pb²⁺ and Cu²⁺ ion concentrations by differential pulse voltammetry (DPV). The electrochemical sensor exhibits excellent electrochemical performance toward Cd²⁺, Pb²⁺ and Cu²⁺ 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 × 10⁻¹⁰ M, 1.92 × 10⁻⁷ M and 3.81 × 10⁻⁷ M, respectively. The fabricated sensor also shows high reliability and good selectivity. This MIL-88B(Fe)-NH₂ application strategy is promising for the evaluation of various heavy metal ions in water.