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

Abstract We report an analytical assessment of an iron oxide (Fe 2 O 3 )/graphene (G) nanocomposite electrode used in combination with in situ plated bismuth (Bi) working as an electrochemical sensor for the determination of trace Zn 2+ , Cd 2+ , and Pb 2+ . 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 Fe 2 O 3 /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 Fe 2 O 3 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 μg L −1 for Zn 2+ , Cd 2+ , and Pb 2+ , and the detection limits were 0.11 μg L −1 , 0.08 μg L −1 , and 0.07 μg L −1 , respectively (S/N =3). Repeatability (% RSD) was found to be 1.68% for Zn 2+ , 0.92% for Cd 2+ , and 1.69% for Pb 2+ for single sensor with 10 measurements and 0.89% for Zn 2+ , 1.15% for Cd 2+ , and 0.91% for Pb 2+ for 5 different electrodes. The Fe 2 O 3 /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.