Fe3O4@PDA@MnO2 core-shell nanocomposites for sensitive electrochemical detection of trace Pb(II) in water

In this study, Fe3O4@PDA@MnO2 core-shell magnetic nanocomposites were synthesized for the first time, and used to enrich target analyte to construct an electrochemical sensor for sensitive detection of trace Pb(II) in the environmental samples. A dense polydopamine (PDA) coating was firstly formed on the surface of Fe3O4 to ensure high stability because the developed method is employed under strongly acidic conditions. Then a high adsorption capacity MnO2 shell can be simply introduced to the surface of the PDA as a result of the redox activity between PDA and KMnO4. Differential pulse voltammetry (DPV) was applied for determining target metal ions. Chemical and electrochemical factors, including quantity of Fe3O4@PDA@MnO2 nanocomposites, preconcentration solutions pH, preconcentration time and supporting electrolytes, were optimized. Under excellent conditions, the designed sensor demonstrated a linear response to Pb(II) within the range of 0.1–150 μg L−1 and with a detection limit of 0.03 μg L−1. The proposed methodology exhibited excellent performance in selectivity, sensitivity and long-term stability, and was also successfully applied to determine Pb(II) in the real water samples. This study suggested that Fe3O4@PDA@MnO2 nanocomposites are a better alternative to Pb(II) analysis resulting from its low cost, low toxicity, strong adsorption, and good reproducibility.