Amperometric solid-state sensor for NO and NO2 based on protonic conduction

Amperometric solid-state sensors for NO and NO2, able to operate at room temperature, are described. These sensors use pellicular cu zirconium phosphate as a proton conductor and two layers of titanium hydride as reference and counter electrode, respectively. Gold or graphite may be employed as sensing electrode. The detection of NO and NO2 takes place in two different ranges of the electrode potential, so that their separate monitoring is possible. In both cases the response is fast even at low concentrations. The best performance is observed for a graphite electrode, for which the detection limits towards NO2 and NO are of the order of 0.01 and 0.2 vpm, respectively.