Electrochemical Detection of Heavy Metal Ions Using Graphene/MOF Modified Electrode

Abstract

Heavy metals pollution is due to agriculture, mining industry, and industrial activities. Once heavy metal ions pollute environment specially water bodies, they are very difficult to degrade by nature for decades. Over time they accumulate in body and pose serious health problems. Because of these effects, it is necessary to detect heavy metal ions. Therefore, It is essential to design such electrode materials with high porosity and large surface area for their wide range of applicability. Metal Organic Framework have been regarded as the promising electrode materials constituting porous carbon-based electrode materials for electrochemical detection of heavy metal ions. In present work, we fabricated cobalt derived Metal Organic Framework comprising of Zeolitic Imidazolate framework (ZIF-67) and then using ZIF-67 as a precursor for the synthesis of graphene oxide (GO) coated ZIF-67 composite through a facile solvothermal synthesis method. Structural analysis of prepared material was done by using FTIR, Raman analysis and XRD. Electrochemical characterization of our prepared composite electrode material was performed through Electrochemical impedance spectroscopy (EIS) and Cyclic Voltammetry (CV) techniques at potential window of -0.2-0.6 mV/s in 5mM [Fe (CN)6]-3/-4 containing 0.1 M KCl using glassy carbon electrode as a current collector. Differential pulse Voltammetry used for individual detection of toxic heavy metal ions such as Pb, Cr, Hg, and As with lower limit of detection i.e 0.01(μM), 0.12(μM), 0.009(μM), and 0.31(μM) respectively below the permissible limit by WHO. Results revealed that synthesized composite (GO/ZIF-67) electrode material has better electrochemical performance as compared to ZIF-67/GCE, GO/GCE, and bare GCE electrode. Therefore, GO/ZIF-67 composite is determined to have good capability as electrode material in heavy metals detection application due to its porous tunable structural composition.