Amperometric hydrogen sensors based on proton-conducting solid electrolytes of compositions are investigated in the present work. The influence of the sensor design on its own characteristics is also examined.
The ceramic samples of the following composition La0.95Sr0.05YO3, CaTi0.95Sc0.05O3 and CaZr0.9Sc0.1O3 were prepared according to the solid-phase synthesis method.
A gaseous mixture of H2+H2O+N2 composition is fed to the channel with flow rate of 70 ml•min-1. All experiments with different hydrogen concentrations have been carried out at 800ºC. The effect of temperature on the limiting current has been separately investigated in the temperature interval 600-850ºC.
It is shown that a solid electrolyte used in the form of discs with cavities significantly simplifies the design of this type of sensors. A sensor based on La0.95Sr0.05YO3 electrolyte with fully sealed junction between discs is suitable for the analysis of mixtures with high H2 content (up to 100%). It is found that by increasing H2 content from 10 to 98% the limiting current increases from 0.25 to 2.25 mA (at 750 mV). It is also found that the sensor based on La0.95Sr0.05YO3 with discs sealed in two points as well as the sensor based on CaZr0.9Sc0.1O3 with fully sealed junction are suitable for the analysis of mixtures with low H2 content (0.5-2%). For the above cases, the limiting current at 2% H2 reaches 3.5 and 0.5 mA (at 750 mV), respectively. CaTi0.95Sc0.05O3 is not suitable to be used as a hydrogen sensor. In all the examined systems, steam content does not affect sensor’s behavior and high operating temperatures (850ºC) increase the range of sensors’ hydrogen measuring concentration capacity.