ELECTROCHEMICAL COMPOSITE CARBON-CERAMIC GAS SENSORS - INTRODUCTION AND OXYGEN SENSING

A new class of sol-gel-derived electrochemical gas sensors, comprised of a homogeneous dispersion of catalyst-modified carbon powder in poro us, organically modified silica, is introduced. The porous structure o f the electrode material permits high gas permeability. Their hydropho bic surface rejects water, leaving only a very thin layer at the outer most surface in contact with the electrolyte and thus minimizing effec ts of liquid side mass transfer. The carbon powder provides electric c onductivity, and the catalyst guarantees selectivity and sensitivity. Heat-treated Co tetramethoxymesoporphyrin modified composite ceramic-c arbon electrodes exemplify this new class of gas sensors. Detection of several gases by anodic (sulfur dioxide) or cathodic (carbon dioxide and oxygen) reactions is demonstrated. Metrological characteristics of a prototype oxygen sensor are presented.