Hydrogen and deuterium influence on BaCe_0.6Zr_0.3Y_0.1O_3-α electrolyte: Effects on ionic conductivity and on sensing performance

The measurement of hydrogen isotopes will be of great interest for future fusion reactors to ensure their proper operation. For this reason, electrochemical sensors will be suitable tools for hydrogen isotopes quantification, as they can perform on-line and in situ measurements. One of the many challenges in hydrogen sensing is finding materials suitable for use at high temperatures and in aggressive environments. In this regard, perovskite-type ceramics exhibit high proton conductivity and excellent physical and chemical stabilities. These properties make perovskite materials ideal candidates for the development of high-temperature hydrogen isotopes sensors. In this study, BaCe_0.6Zr_0.3Y_0.1O_3-α electrolyte was employed to fabricate amperometric sensors to monitor hydrogen isotopes. First, the ionic conductivity of the electrolyte was measured for hydrogen and deuterium using Electrochemical Impedance Spectroscopy (EIS) in order to determine isotopic effects. It was observed a protonic conduction as the governing transport mechanism. In addition, the ratio between the ionic conductivity of hydrogen and deuterium was 1.2–1.4. Then, amperometric measurements were performed at 350, 400, and 500 °C, while maintaining a voltage of 0.15 V between electrodes. The sensors' performance was assessed for hydrogen and deuterium partial pressures ranging from 0.15 to 0.30 mbar within an argon atmosphere. Calibration curves for both isotopes exhibited differences of approximately 20% in their slopes, which agrees with the trend observed in the ionic conductivity results. Additionally, the response time to hydrogen was three times faster compared to that observed for deuterium. These findings suggest that electrochemical sensors utilizing solid-state electrolytes, such as BaCe_0.6Zr_0.3Y_0.1O_3-α, holds great promise as an innovative and effective tool for hydrogen isotope sensing.