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 porous, organically modified silica, is introduced. The porous structure of the electrode material permits high gas permeability. Their hydrophobic surface rejects water, leaving only a very thin layer at the outermost surface in contact with the electrolyte and thus minimizing effects of liquid side mass transfer. The carbon powder provides electric conductivity, and the catalyst guarantees selectivity and sensitivity. Heat-treated Co tetramethoxymesoporphyrin modified composite ceramic-carbon 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.