Electrochemical investigation of gold/silica thin film interfaces for electrochemical surface plasmon resonance studies

The paper reports on the electrochemical behaviour of a thin gold film electrode coated with a 9.7 nm thick silicon dioxide (SiOx) layer. Chemical and mechanical stable SiOx layers on gold were synthesised by plasma enhanced chemical vapour deposition (PECVD). The electrochemical behaviour of the thin gold film electrodes with or without SiOx coating were compared using cyclic voltammetry (CV) in potassium chloride solutions and in the presence of an electrochemical redox mediator (Fe(CN)64-). These studies showed that homogeneous thin SiOx layers are formed on gold, protecting efficiently the gold electrode from anodic dissolution, while preserving electrochemical mass transfer at the interface. The electrochemical dissolution of the uncoated thin gold film was further evidenced by coupled surface plasmon resonance (SPR) studies.