Development of α-polyoxometalate–polypyrrole–Au nanoparticles modified sensor applied for detection of folic acid

•An in-situ fabricated sensing film is described.•The film has a remarkable electrocatalytic activity.•The film has a reduced over-potential.•The sensor can distinguish FA in physiological pHs.

In this work, electrochemically synthesized gold nanoparticles (AuNPs) and α-polyoxometalate (α-POM) (K7PMO2W9O39·H2O) were simultaneously doped into electropolymerized polypyrrole (PPy) film using the cyclic voltammetry (CV) technique. Scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and CVs were used to characterize the composite films. The PPy–α-POM–AuNPs modified gold (Au) electrode was used to determine folic acid (FA) using square-wave voltammetry (SWV). The modified electrode exhibited excellent electrocatalytic ability to the reduction of FA at 0.3 V (vs. SCE) with the electron transfer rate constant (ks) of 1.15×10−19 s−1. The common coexisting substances showed no interferences on the response of modified electrode to FA. The modified electrode indicated reproducible behavior and a high level stability during the experiments, making it particularly suitable for the analytical purposes.