Enhancement of Electrochemical Oxidation of Glucose at Hg Adatom-modified Au Electrode in Alkaline Aqueous Solutions

Abstract

Origin of enhanced electrochemical oxidation of glucose observed around 0.3 V (vs. Ag/AgCl (KCl sat.)) on an Hg adatom-modified Au polycrystalline electrode in alkaline aqueous solutions was investigated by cyclic voltammetry in various potential regions and solution pH's. The enhanced oxidation current was stable under continuous cycling between - 0.55 and 0.35 V. Positive scanning of potentials to greater than 0.35 V caused the oxidation current to decrease with dissolution of the UPD adlayer of Hg from the Au electrode. The surface structure of the Hg adatom-modified Au electrode found to be highly important in glucose oxidation. Moreover, pH dependence of the enhancement of glucose oxidation was attributed to the amount of adsorbed OH^- on the Hg adatom-modified Au electrode. The investigation revealed that the surface structure on the Hg adatom-modified Au electrode cased an increase in the amount of adsorbed OH^- on the Hg adatom-modified Au electrode around 0.35 V. It was considered that OH_ad produced by partial discharge of OH^- on the Hg adatoms and/or oxide layer (Au(OHad)) of Au surface catalyzed the oxidation of glucose on the Hg adatom-modified Au electrode.