Construction of a heteropolyanion-modified electrode by a two-step sol–gel method and its electrocatalytic applications

The sol–gel technique was used here to construct heteropolyanion-containing modified electrodes. This involves two steps, i.e. the first forming a functionalized sol–gel thin film on the surface of the glassy carbon electrode and then immersing the electrode into a heteropolyanion solution to incorporate the heteropolyanion into the sol–gel film. Here a Dawson-type heteropolyanion, K6P2W18O62 (P2W18), was used as a representative to illuminate the behavior of the as-prepared composite film. The electrochemical performance of the P2W18-modified electrode was studied with respect to the pH effect and long-term stability. The modified electrode exhibited a high electrocatalytic response for the reduction of BrO3− and NO2−. Steady-state amperometry was applied to characterize the electrode as an amperometric sensor for the determination of NO2−. The sensor had a linear range from 0.02 to 34 mM and a detection limit of 5×10−6 M.