Application of Solid oxide proton-conducting electrolytes for amperometric analysis of hydrogen in H2+N2+H2O gas mixtures

Amperometric hydrogen sensors based on proton-conducting solid electrolytes of La0.95Sr0.05YO3, CaTi0.95Sc0.05O3 and CaZr0.9Sc0.1O3 compositions are prepared and investigated in the present work. The influence of the sensor design on its own characteristics is also examined. 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 H-2 content. 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 H-2 content (0.5-2%). For the above cases, the limiting current at 2% H-2 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 sensors' behavior and high operating temperatures (850 degrees C) increase the range of sensors' hydrogen measuring concentration capacity. (C) 2014 Elsevier Ltd. All rights reserved.