Incorporation of Fe2O3 Spacer Molecules in Microwave-Exfoliated Graphene Oxide as Efficient Electrodes for Simultaneous Detection of Cd2+, Pb2+, and Hg2+ in Water

Abstract

Toxic adverse effects to human beings caused by heavy metal ions resemble a serious threat to mankind and often appear in the journal headlines. However, simultaneous detection of heavy metal ions using analytical tools is challenging. In this regard, simultaneous electrochemical detection of Cd2+, Pb2+, and Hg2+ ions in water is presented using iron oxide (Fe2O3) nanostructures as spacers incorporated between microwave-exfoliated graphene oxide (MEGO). First, Fe2O3 nanostructures are synthesized using ferric nitrate in presence of poly(vinylpyrrolidone) and followed by their in-situ incorporation into expanded graphene oxide (GO). Exfoliated GO accommodates large amount of Fe2O3 nanoparticles via microwave-assisted method, minimizing the restacking of GO sheets. Consequently, Fe2O3-incorporated MEGO (Fe2O3-MEGO) fabricated on screen-printed electrodes (SPE) demonstrate well-separated anodic peak potentials at -0.65, -0.45, and +0.27 V for Cd2+, Pb2+, and Hg2+ ions. Moreover, Fe2O3-MEGO/SPE electrode exhibits wide linear range (0.4 to 74.78 mu M), high sensitivities (8.11, 9.59, and 3.01 mu A mu M-1 cm(-2)) with low detection limits (0.2, 0.17, and 0.25 mu M) for Cd2+, Pb2+, and Hg2+ ions, respectively. Therefore, this kind of incorporating nanomaterials as spacer molecules between GO allows for the design of alternative pathways to minimize restacking of GO and to increase sensitivity toward multiple targeted species.