An amperometric sensor of iodate based on the composite film of a crown heteropolyanions and Cu@Ag nanoparticles

• A sensor for detection of IO3− was constructed using P8W48 and Cu@AgNPs.
• The sensor has good performance in LOD, selectivity and longer-term stability.
• The sensor also shows a good recovery in practical table salt samples detection.

A new composite film based on K28Li5H7 [P8W48O184]·92H2O (P8W48) and Cu@AgNPs was fabricated by the layer-by-layer assembly method and characterized by UV–vis spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The electrochemical properties of the composite film were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and current–time response techniques. Comparative experiments revealed that the electrocatalytic efficiency of the composite film toward reduction of iodate was significantly enhanced by the combined effects of P8W48 and Cu@AgNPs. The proposed sensor based on this composite film exhibited a high sensitivity of 5.52 A/M, a broad linear range from 1.0 × 10−7 to 3.0 × 10−4 M and a low detection limit of 4.0 × 10−8 M (S/N = 3) for detection of iodate. The sensor was also explored to detect iodate in the commercial salt samples, and the experimental results showed that the recovery was within allowable error range.