Highly sensitive detection of Pb²⁺ and Cu²⁺ based on ZIF-67/MWCNT/Nafion-modified glassy carbon electrode

A series of different facile modification layers (MLs) was designed to gradually increase the electrochemical sensing performance of glassy carbon electrode (GCE) for simultaneously detecting Pb²⁺ and Cu²⁺. ML designs were mainly a different combination of ZIF-67, MWCNT and Nafion, and their different electrochemical sensing performances were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), square wave stripping voltammetry (SWSV) and chronocoulometry. The fabricated sensor, which modified with ZIF-67/MWCNT and Nafion layer, exhibited the biggest response peak current to Pb²⁺ and Cu²⁺. In addition, it displayed a wide linear detection range of 1.38 nM-5 μM for Pb²⁺ and 1.26 nM-5 μM for Cu²⁺, a detection accuracy of about 1 nM for both Pb²⁺ and Cu²⁺, and an excellent stability for both Pb²⁺ and Cu²⁺. We also analyzed the real water sample taken from Changchun's Sanjia Lake and Yan Lake. We believe this ML design provides instruction for building high-performance electrochemical sensing systems.