Electrochemical oxidation of glucose on single crystal gold surfaces

Abstract

The electrooxidation of glucose has been studied extensively because of the interest in the development of the glucose sensor [l] and the glucose-oxygen fuel cell [2] for cardiac pacemakers and artifical hearts. The understanding of the reaction kinetics is far from complete. It has been established, however, that the oxidation of glucose is a typical electrocatalytic reaction whose kinetics depend on the nature of the electrode material [3,4]. Platinum, as the electrode material, has been the subject of most of the studies, although gold displays a higher activity in neutral and alkaline electrolytes [4]. The pronounced poisoning of the platinum electrode by some intermediates and/or products apparently suppresses its intrinsic activity for the initial stages of the reactions. The crystal plane dependence of the electrooxidation of small organic molecules with similar poisoning effects is now well documented [5,6]. Therefore, the oxidation of glucose is expected also to be structure sensitive. Kokkinidis et al. [7] indeed have found different catalytic activities for glucose oxidation on the low-index platinum surfaces in acid solution. The Pt (111) surface has a higher activity than the other two low-index planes as a consequence of a lower self generated poison effect on this surface. The present research has indicated that gold appears to be a more active electrocatalyst for glucose oxidation in neutral and alkaline electrolytes, which makes it an attractive choice for sensor application. This calls for a study of the glucose oxidation on single crystal gold electrodes in order to determine which