Transport of redox active probes in silica sol-gel glass with embedded organic electrolyte

The transport of the redox active probes (ferrocene and Co(II)tris((bipyridine)) in silica sol-gel glass with embedded organic electrolyte has been studied. The material was prepared by acid-catalysed hydrolysis of the tetramethylorthosilicate sol mixed with lithium or tetraethylammonium perchlorate solution in sulpholane. The solid electrolyte was obtained as monolith with immersed electrodes. The rate of transport of the redox probes within modified sol-gel glass has been estimated by means of apparent diffusion coefficients by chronoamperometry on ultramicroelectrodes. The value of this parameter substantially decreases during the first few days after gelation and later it becomes weakly dependent on aging. The linear Arrhenius plots of the apparent diffusion coefficients of redox probes in sol-gel material and in analogous liquid electrolyte were obtained. Their similar slope indicates that silicate matrix acts as porous reservoir for the organic electrolyte. (C) 2002 Elsevier Science B.V. All rights reserved.