title: Electrooxidation of nitrite on a silica-cerium mixed oxide carbon paste electrode.
abstract: A 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 459 m(2) g(-1). Infrared spectroscopy of the SiCe material showed the formation of the Si-O-Ce 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 (29)Si 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 Ce(3+)/Ce(4+) at 0.76 V 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 0.76 V with a linear response as the concentration of the analyte increases from 3×10(-5) at 3.9×10(-3) mol L(-1).
authors.affiliation: Instituto de Química, Universidade Federal de Alfenas, Alfenas, MG, Brazil.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Silveira
authors.forename: Andréia
authors.initials: A
authors.lastname: de Morais
authors.forename: Paulo César Mendes
authors.initials: PC
authors.lastname: Villis
authors.forename: Camila Marchetti
authors.initials: CM
authors.lastname: Maroneze
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Gushikem
authors.forename: Alzira Maria Serpa
authors.initials: AM
authors.lastname: Lucho
authors.forename: Fábio Luiz
authors.initials: FL
authors.lastname: Pissetti