Electrochemical redox reaction in a silica sol-gel glass with embedded organic electrolyte

The electrochemical redox reaction of ferrocene was studied in silica sol-g el glass with embedded organic electrolyte. This material has been prepared by mixing hydrolysed tetramethylorthosilicate sol with propylene carbonate LiClO4 solution containing ferrocene and further gelation in a form of blo ck or film. The electrochemical behaviour of encapsulated ferrocene was stu died by cyclic voltammetry, chronoamperometry, differential pulse voltammet ry and impedance spectroscopy on ultramicroelectrodes. The shape of the cyc lic voltammograms corresponding to the electrooxidation of ferrocene in sol -gel block is similar to that obtained in liquid electrolyte and it does no t depend on gel aging. The current substantially decreases during the first few days after gelation. Later it becomes weakly dependent on aging and th e apparent diffusion coefficient of ferrocene in the gel block is about hal f of that in liquid electrolyte. The electrooxidation of ferrocene also occ urs in film of the analogous sol-gel material cast on the surface of the el ectrode assembly. (C) 2000 Elsevier Science S.A. All rights reserved.