Doping ZIF-67 with transition metals results in bimetallic centers for electrochemical detection of Hg(II)

• Published in: Electrochimica acta Vol. 387; p. 138539
• Main Authors: Chen, Xing, Zhao, Ji-Xing, Wang, Jia-Wei, Liu, Yao, Wang, Lian-Chao, Weerasooriya, Rohan, Wu, Yu-Cheng
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 10.08.2021; Elsevier BV
• Subjects: Anodic stripping; Bimetals; Doping; Electrochemical analysis; Electrochemical detection; Electron transfer; Heavy metals; Iron oxides; Liquid-solid interfaces; Manganese; Mercury; Mercury (metal); Mercury compounds; Metal ions; Metal-organic framework; Metal-organic frameworks; Nanocomposites; Nickel; Square waves; Substrates; SWASV; Transition metal; Transition metals; Voltammetry; Metal-organic framework; SWASV; Transition metal; Electrochemical detection; Mercury
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2021.138539

Development of robust methods for rapid detection of heavy metal ions and associated chemical species in water is challenging. Different mercury species are ubiquitous in the environment; they bio-amplify and undergo methylation into organo-Hg species. We developed a new electrochemical method for rapid screening of free Hg2+ in water by square wave anodic stripping voltammetry (SWASV) on a metal-organic framework (MOF) platform using ZIF-67 as starting substrate. Bimetallic MOF structures were fabricated by doping iron, manganese or nickel ions into ZIF-67 using a facile NaOH treatment. The GCE was modified with Ni, Mn, or Fe doped ZIF-67 nanocomposites to enhance performance for Hg2+ detection. When compared to pure ZIF-67/GCE, the Hg2+ detection sensitivity by the metal ions-doped ZIF-67/GCE was increased by 260%. The detection limit was improved by 60%. The Fe doping on ZIF-67 (FexCoy) significantly improves electroanalytical performance due to the formation of iron oxide on ZIF-67. The GCE modified with Fe1Co1 nanocomposite showed the best performance for electrochemical detection of Hg2+. Besides, the cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS) data also confirmed that Fe doping of the ZIF-67 enhanced the electron transfer rate at the solid-liquid interface. Hg2+ detection and quantification at this new chemically modified sensing electrode were not interfered by Cd2+, Pb2+, and Cu2+. The Fe1Co1 modified GCE is stable when used repeatedly for ten cycles. The spike recovery of 0.3 to 1.00 µM Hg2+ with Fe1Co1 modified GCE was always above 99.0%. The chemically modified sensor with Fe1Co1 holds a promise in monitoring Hg2+ at trace concentrations.