Sol-gel-derived carbon ceramic electrode containing 9,10-phenanthrenequinone, and its electrocatalytic activity toward iodate

9,10-Phenanthrenequinone (PQ) supported on graphite powder by adsorption wa s dispersed in propyltrimethoxysilane-derived gels to yield a conductive co mposite which was used as electrode material to fabricate a PQ-modified car bon ceramic electrode. In this configuration, PQ acts as a catalyst, graphi te powder guarantees conductivity by percolation, the silicate provides a r igid porous backbone, and the propyl groups endow hydrophobicity and thus l imit the wetting region of the modified electrode. Square-wave voltammetry was exploited to investigate the pH-dependent electrochemical behavior of t he composite electrode and an almost Nernstian response was obtained from p H 0.42 to 6.84. Because the chemically modified electrode can electrocataly ze the reduction of iodate in acidic aqueous solution (pH 2.45), it was use d as an amperometric sensor for the determination of iodate in table salt. The advantages of the electrode are that it can be polished in the event of surface fouling, it is simple to prepare, has excellent chemical and mecha nical stability, and the reproducibility of surface-renewal is good.