Mesoporous Silica Sputter‐Coated onto ITO: Electrochemical Processes, Ion Permeability, and Gold Deposition Through NanoPores

Simple silica films of 50 nm and 100 nm thickness are sputter-coated onto ITO substrates and shown to be structured with in-planed features of ca. 15 nm and pores <5 nm (based on GISAXS). In electrochemical measurements membrane pore effects are observed. The oxidation current for Fe(CN)64- in aqueous KNO3 strongly depends on the electrolyte concentration. Poly-cationic poly(diallyl-dimethylammonium) (PDDA) cannot enter these pores, but is adsorbed onto the outer surface of the silica film. During gold electrodeposition, PDDA causes growth of discs. Gold deposits adhere well and a comparison of glucose electrooxidation activity reveals significant improvements.