Electrochemical fabrication of copper-containing metal–organic framework films as amperometric detectors for bromate determination

Abstract

A facile electrochemical plating strategy has been employed to prepare the electroactive metal–organic framework film (NENU-3) onto a copper electrode in the acid electrolyte containing 1,3,5-benzenetricarboxylic acid (H₃BTC) and phosphotungstic acid (PTA). The as-made NENU-3 films have been characterized using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analyses (TGA). These analyses indicate that NENU-3 films have high phase purity and high stability. Further, different electrochemical techniques are utilized for measuring the electrochemical behaviors of the NENU-3 film electrodes. Accordingly, the kinetic parameters of a NENU-3 film electrode towards the electrocatalytic reduction of bromate are obtained, including the electron transfer coefficient (α), the catalytic rate constant (k_s), and the diffusion coefficient (D). The film electrodes present excellent electrocatalytic ability for the bromate reduction, and can be used successfully for the amperometric detection of bromate. Under the optimized conditions, the proposed sensor exhibits a wide linear range (0.05–72.74 mM) and a lower detection limit (12 μM) measured by chronoamperometry (CA). Moreover, the films possess high electrochemical stability and strong anti-interference capability in the bromate detection process. It has been demonstrated that the electrochemical plating method reported here offers a reliable and efficient way to fabricate MOF films on conductive substrates for bromate detection.