Humidity Tolerance of Electrochemical Hydrogen Safety Sensors Based on Yttria-Stabilized Zirconia (YSZ) and Tin-doped Indium Oxide (ITO)

Commercial hydrogen sensors are available, but performance and cost targets remain unmet for many hydrogen economy applications. For example, traditional thermal conductivity detectors (TCDs) can be responsive to combustible gases in general, show humidity effects, and are relatively costly. New options under development include solid-state electrochemical sensors, which are low cost, can be operated over various temperature and humidity ranges, have fast response times, and can show low cross-sensitivity to hydrocarbons. Previous work demonstrated potentiometric sensors based on yttria-stabilized zirconia (YSZ) and tin-doped indium oxide (ITO). In this study, prototypes were investigated for humidity tolerance. Electrochemical characterization indicated similar reaction rates for negative and positive potentials could be important for humidity tolerance. More advanced prototypes were developed to demonstrate miniaturization and robust packaging for cross-validation testing. Additional electronics were developed for compatibility with data acquisition systems, and results validated humidity tolerance for H₂ sensors up to 10% water in air.