Influence of a Nanoscale Gold Thin Layer on Ti/SnO2-Sb2O5 Electrodes

Abstract

A nanoscale gold thin film and its influence on Ti/SnO2-Sb2O5 coating have been investigated by scanning electron microscopy (SEM) and electrochemical methods such as cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and the chronopotentiometric technique in both acidic and caustic solutions. The gold thin film was fabricated by sputtering, and its thickness was estimated using electrochemical methods. The nanoscale gold thin film on the titanium substrate exhibits electrochemical behavior similar to that of a polycrystalline Au electrode. Our study shows that the presence of a nanoscale Au thin film on the Ti substrate can effectively prevent the growth of a TiO2 insulating layer between the substrate and the SnO2-Sb2O5 coating, resulting either from the thermal procedure during the fabrication of the oxide electrodes or from the electrochemical process during the lifetime tests, thus greatly prolonging the service lifetime of the SnO2-Sb2O5 electrodes. The failure mechanisms of the SnO2-Sb2O5 electrodes have also been studied using the EIS and SEM techniques.