An electrochemical sensor based on a glassy carbon electrode modified with sandwich structured ZIF-67@rGO for bisphenol A measurement

Abstract

The low conductivity of metal–organic frameworks seriously impedes their electrocatalytic performance. In this study, we prepared a fabricated sandwich structure composed of a Co-based zeolitic imidazolate framework (ZIF-67) and reduced graphene oxide (rGO) through a facile and simple one-pot hydrothermal reaction. This framework of nanocomposites, which are modified with a glassy carbon electrode, constructed a bisphenol A (BPA) electrochemical sensor for the first time. Operational parameters such as pH, electrolytes, the amount of modifiers, deposition potentials and deposition time were optimised for the sensitive detection of BPA. The performance of electrodes was evaluated by cyclic voltammetry, electrochemical impedance spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction and transmission electron microscopy. With differential pulse voltammetry, the detection concentration of BPA ranged from 0.05 μmol L⁻¹ to 100 μmol L⁻¹. The results revealed that the hierarchical nanocomposites demonstrated better electrocatalytic performance with large electrochemically active surface areas, high sensitivity and a low limit of detection (5.2 nmol L⁻¹), compared with a physical mixture of ZIF-67 and rGO at the same ratio. These impressive features originate from the synergistic effects of ZIF-67 and rGO. This study presents a new strategy using metal–organic framework composite materials for the sensitive detection of BPA.