Amperometric solid-state gas sensors:: Materials for their active components

Principal materials used for the active components of amperometric solid-state gas sensors, namely, the electrolytes and electrode materials, are reviewed. Inorganic proton conductors, solid polymers, and hydrogels are the most frequently used electrolytes. Electrode materials are discussed with the respect both to the catalytic activity (pure metals and carbon, catalyst films, and composites) and electrode geometry (the length of the three-phase boundary). Basic properties of the sensors with these materials are discussed briefly.