Morphology dependent electrocatalytic activity of Au nanoparticles

The electrocatalytic activity of spherical shape Au particles chemically grown on a sol-gel derived 3D silicate network modified conducting surface has been studied using ascorbate as a model. The nanostructured Au particles show morphology dependent electrocatalytic activity towards ascorbate. Unusual voltammetric behavior for ascorbate has been observed. Unlike the polycrystalline Au electrode, the nanostructured electrode shows two well defined voltammetric peaks for ascorbate at 0 and 0.3 V in neutral and alkaline pHs. These voltammetric peaks are assigned for the oxidation of ascorbate to dehydroascorbate (DHA) and the further oxidation of 2,3-diketogluonic acid (DKG), the hydrolyzed product of DHA. The voltammetric peak corresponding to the oxidation of DKG is very sensitive to the supporting electrolyte anions and solution pH. Voltammetric behavior of DHA has been investigated to support the oxidation pathway of ascorbate on the nanostructured electrode. Surface morphology of the particle controls the electrocatalytic activity. (C) 2008 Elsevier B.V. All rights reserved.