(Bio)electrocatalysis at tin-doped indium oxide nanoparticulate film decorated with gold

Abstract

A novel hybrid material was assembled using an electrode of tin-doped indium oxide modified by a nanoparticulate (ITONP) film decorated with gold nanoparticles nanoparticles. The ITONP film was deposited by subsequent immersions and withdrawals of the substrate into a suspension ITONP. The gold nanoparticles were electrogenerated at a three-phase junction using chronoamperometry. The obtained structures were characterized by scanning electron microscopy and by transmission electron microscopy (TEM) with techniques of energy-dispersive X-ray spectroscopy and high angle annular dark field contrast analysis. The cross-section of the ITO nanoparticulate film exhibited that the whole ITONP film forms a three dimensional scaffold accessible for gold nanoparticle deposition. The ITONP film electrodes modified with gold nanoparticles showed high electrochemical activity towards glucose oxidation and dioxygen reduction with linear dependence on the thickness of the ITO nanoparticulate film. Additionally, for the second reaction, bilirubin oxidase was adsorbed on the modified surface and mediatorless bioeletrocatalytic activity was observed. In all cases a notable increase of the current magnitude was observed due to development of the nanoparticulate film and good access to the gold nanoparticles. A significant decrease of the overpotential for non-enzymatic dioxygen reduction was noted on the AuNP modified electrodes.