Electrochemical Oxidation of Ascorbic Acid on Gold Nanoparticles Coated Pt

Nanomaterials exhibit unique chemical [1-3], physical [47] and electronic [8] properties that are distinctly different from those of bulk materials and depend on size, shape and surface composition of the nanostructured materials. Nanomaterials of noble metals are finding worldwide interest in research communities [9-12]. Several reviews have highlighted the role of metal nanoparticles in catalysis [13-15]. The small size of the nanoparticles endows them with a high surface area, providing more active sites to catalyse reactions and with the ability to electronically interact with the reactant molecules, providing significant improvement in both detection and catalytic capabilities. Because of these properties, nanoparticles are finding applications in electroanalysis and electrochemical based sensors. In electrochemical experiments, nanoparticles based electrodes are rapidly replacing the conventional macroelectrodes because of the large effective surface area, increased mass transport, high catalytic activity and the ability to exert control over the local environment at the nanoparticles-modified electrode surface [16]. Gold nanoparticles have found applications as catalysts and biosensors in various chemical and biological reactions of interest, including biological labeling in medical imaging, because of the nanoparticles’ biocompatibility and easy functionalization of the surfaces. The surface of the gold nanoparticles is generally functionalized to prepare sensors, but some of the analytes can be detected at the nanoparticles-modified electrode. Electrochemical deposition is commonly used to synthesize and deposit metal nanoparticles onto the substrate simultaneously, with easy control of particle morphology. Therefore, electrochemical deposition is a potentially powerful and convenient technique, to regulate catalytic properties of the nanoparticles. This paper describes the electrochemical oxidation of ascorbic acid on nanostructured gold coated Pt electrode. The dependence of peak current (i p ) and peak potential (E p ) of ascorbic acid oxidation, on the numbers of cyclic voltammetry (CV) cycles used for gold deposition was studied.