High temperature potentiometric hydrogen sensor based on BaCe_0.6Zr_0.3Y_0.1O_3-α-ZnO

One of the alternatives to carbon-based fuels is hydrogen. Hydrogen isotopes are expected to be used as a fuel for nuclear fusion power. The measurement of these isotopes in high-temperature environments (>350 °C) is of great interest. Electrochemical sensors based on solid-state electrolytes have been proved to be able to operate at elevated temperatures, with great physical and chemical stabilities. In the present work, BaCe_0.6Zr_0.3Y_0.1O_3-α (BCZY) was used as a proton-conducting solid-state electrolyte. The synthesized powder was shaped into pellets at 1400 °C for 30 h and 1650 °C for 6 h and adding 5 mol% ZnO as sintering aid at mild sintering conditions (1400 °C for 12 h). Electrochemical sensors were constructed and tested using these pellet shaped electrolytes. The sensors were used in a potentiometric configuration at 400 °C, 500 °C and 600 °C. Hydrogen concentrations in the working electrode ranged from 0.02 to 0.5 mbar H₂ in Ar. The use of ZnO as sintering aid helped in the obtention of full dense ceramics, preserving the perovskite structure of the electrolyte. Moreover, the addition of ZnO yielded a sensor that practically fulfilled the Nernst equation and able to perform hydrogen measurements with a high accuracy and precision.