A sensitive electrochemical sensor using an iron oxide/graphene composite for the simultaneous detection of heavy metal ions

We report an analytical assessment of an iron oxide (Fe2O3)/graphene (G) nanocomposite electrode used in combination with in situ plated bismuth (Bi) working as an electrochemical sensor for the determination of trace Zn2+, Cd2+, and Pb2+. The as-synthesized nanocomposites were characterized by transmission electron microscopy, scanning electron microscopy, thermo-gravimetric analyzer, and X-ray diffraction. The electrochemical properties of the Fe2O3/G/Bi composite modified electrode were investigated. Differential pulse anodic stripping voltammetry was applied for the detection of metal ions. Due to the synergetic effect between graphene and the Fe2O3 nanoparticles, the modified electrode showed improved electrochemical catalytic activity high sensitivity toward trace heavy metal ions. Several parameters such as the preconcentration potential, bismuth concentration, preconcentration time, and pH were carefully optimized to determine the target metal ions. Under optimized conditions, the linear range of the electrode was 1-100 mu g L-1 for Zn2+, Cd2+, and Pb2+, and the detection limits were 0.11 mu g L-1, 0.08 mu g L-1, and 0.07 mu g L-1, respectively (S/N = 3). Repeatability (% RSD) was found to be 1.68% for Zn2+, 0.92% for Cd2+, and 1.69% for Pb2+ for single sensor with 10 measurements and 0.89% for Zn2+, 1.15% for Cd2+, and 0.91% for Pb2+ for 5 different electrodes. The Fe2O3/G/Bi composite electrode was successfully applied to the analysis of trace metal ions in real samples. The solventless thermal decomposition method applied to the simple and easy synthesis of nanocomposite electrode materials can be extended to the synthesis of nanocomposites and promising electrode materials for the determination of heavy metal ions. (C) 2016 Elsevier B.V. All rights reserved.