Fabrication of carbon paste electrode containing [PFeW11O39]4− polyoxoanion supported on modified amorphous silica gel and its electrocatalytic activity for H2O2 reduction

[PFeW11O39]4− (PFeW11) supported on the surface of 3-aminopropyl(triethoxy)silane modified silica gel was synthesized and used as a bulk modifier to fabricate a renewable three-dimensional chemically modified electrode. The electrochemical behavior of the modified electrode was investigated. Cyclic voltammetry studies showed that the PFeW11 on the electrode surface sustained the same electrochemical properties as that of the PFeW11 in solution. The preparation of chemically modified electrode is simple and quiet reproducible using inexpensive material. The modified electrode had high electrocatalytic activity toward H2O2 reduction and it was successfully applied as an electrochemical detector to monitor H2O2 in flow injection analysis (FIA). The electrocatalytic peak current was found to be linear with the H2O2 concentration in the range 10–200 μmol L−1 with a correlation coefficient of 0.998 and a detection limit (3σ) of 7.4 μmol L−1 H2O2. The electrode has the remarkable advantage of surface renewal owing to bulk modification, as well as simple preparation, good mechanical and chemical stability and reproducibility.