Characterization of proton-conducting electrolyte based on La0.9Sr0.1YO3 – δ and its application in a hydrogen amperometric sensor

Abstract

In the present study, a Sr-doped LaYO3 proton-conducting material is successfully synthesized by the citrate–nitrate combustion method and its phase features, microstructure, thermal behavior and transport properties are investigated by the aid of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), dilatometry and four-probe dc electrical measurements. The set of the data obtained (single-phase structure, nonporous ceramic, low thermal expansion such as 10.5×10–6K–1 and predominant ionic transport in oxidizing and reducing atmospheres even at 900°C), allows one to propose this material as an electrolyte component for hydrogen amperometric sensors. To this purpose, a sensor, containing two electrochemical cells based on oxygen anionic YSZ and protonic La0.9Sr0.1YO3–δ electrolytes, is constructed and its electrochemical properties are investigated under different conditions, including different H2+N2 gas mixtures and temperatures. The possibility of direct measurement of hydrogen content in nitrogen on the base of the limiting current value is shown. It is found that the developed sensor exhibits good operation reproducibility, clear response and precision for the detection of trace hydrogen content (0.1–3.3 vol.%) in process gases at 500–600°C.