Sol-gel-derived silicate-based composite electrode

Sol-gel is an elegant, room temperature, wet-chemistry method for the synthesis of biohybrids and composite materials. Its benefits stem from its user friendliness, low-cost precursors, the versatility of silicate and organosilane chemistry, and large number of thin film coating processes such as spin, dip, spread, and spray coating as well as electric field-assisted deposition techniques. As such, it is now an essential ingredient in the toolbox of electrochemists, and it is routinely used for the fabrication of electrochemical cells, gel electrolytes, electrodes, and sensors. During a decade of intensive research at the eve of the last millennium, a large variety of possible sol-gel precursors were commercialized or synthesized in different laboratories, the basic features of sol-gel processing have emerged, a large number of possible fields of applications were described, and the main capabilities of the technology as well as some of its limitations were unraveled. A large research effort was devoted to electrochemical sensing whose conflicting requirements in the micro and macro domains could be reconciled by composite sol-gel materials. Two classes of composite materials have become widely accepted and are reviewed in-depth in this chapter: (i) inorganic or organic polymer-silicate composites and (ii) graphite or metal grain-loaded silicates and ormosils.