Electrosynthesis of thin sol–gel films at a three-phase junction

Thin, functionalised silica films of between 4 and 15 nm thickness were prepared by sol–gel processing at an electrode organic phase aqueous phase junction by slow withdrawal of a conducting support through the liquid–liquid interface. Protons were electrogenerated in the aqueous phase and catalysed the hydrolysis of the sol–gel precursor in the organic phase. The film was characterised using atomic force microscopy, scanning electron microscopy, ellipsometry, infrared spectroscopy, voltammetry and scanning electrochemical microscopy. The thickness, electrodeposited on gold, was determined to be less than 10 nm and the density of imidazolium functional groups was estimated to be 1.2 molecules nm−2. The film obtained on ITO is approximately twice thicker compared to the gold support.

Research highlights▶ We introduce a new method for electrodeposition of thin silicate films. ▶ The film was deposited using a three-phase junction as a micro-reactor. ▶ This enabled deposition from a pure imidazolium containing ionic liquid silicate precursor. ▶ The film has a high functional group density. ▶ The functionalised film is a good support for, e.g. layer-by-layer deposition.