Sol–gel route to advanced nanoelectrode arrays (NEA) based on titania gold nanocomposites

Abstract

A simple sol–gel-coating strategy has been used to prepare below 10 nm thin nanostructured oxide (TiO₂) membranes on conducting surfaces. Well calibrated (20 nm in diameter) and homogeneously dispersed nanoperforations are embedded into the membranes, altogether forming highly ordered and dense nanoelectrode arrays (NEAs) or patterns. Controlling the deposition conditions and the solution chemistry allowed for the formation of homogeneous membranes on very hydrophobic, and difficult to wet surfaces, such as gold. Calibrated pore size and interpore spacing are controlled through the self-assembly of macromolecular templates with the inorganic precursors upon evaporation. Structures were assessed by AFM and SEM-FEG, while XPS allowed us to estimate surface chemical state and composition. Cyclic voltammetry was used to describe the diffusion regime and the accessibility of the conducting nanosurfaces. We also show, using surface-tension measurement, that the ceramic matrix can be selectively chemically modified, which is an easy method to adjust the surface chemical nature of an electrode without altering its electron-transfer properties. It thus constitutes a novel route to hybrid organic–inorganic nanostructured surfaces with extended multifunctionality.