Electrooxidation of nitrite on a silica–cerium mixed oxide carbon paste electrode

AbstractA silica–cerium mixed oxide (SiCe) was prepared by the sol–gel process, using tetraethylorthosilicate and cerium nitrate as precursors and obtained as an amorphous solid possessing a specific surface area of 459m2g−1. Infrared spectroscopy of the SiCe material showed the formation of the SiOCe linkage in the mixed oxide. Scanning electron microscopy/energy dispersive spectroscopy indicated that the cerium oxide particles were homogenously dispersed on the matrix surface. X-ray diffraction and 29Si solid-state nuclear magnetic resonance implied non-crystalline silica matrices with chemical environments that are typical for silica-based mixed oxides. X-ray photoelectron spectroscopy showed that Ce was present in approximately equal amounts of both the 3+ and 4+ oxidation states. Cyclic voltammetry data of electrode prepared from the silica–cerium mixed oxide showed a peak for oxidation of Ce3+/Ce4+ at 0.76V and electrochemical impedance spectroscopy equivalent circuit indicated a porous structure with low charge transfer resistance. In the presence of nitrite, the SiCe electrode shows an anodic oxidation peak at 0.76V with a linear response as the concentration of the analyte increases from 3×10−5 at 3.9×10−3molL−1