Room-Temperature Hydrogen Sensors Based on an In[sup 3+]-Doped SnP[sub 2]O[sub 7] Proton Conductor

A potentiometric solid-state gas sensor was fabricated using a proton-conducting electrolyte with an active working electrode in order to study its sensing properties for small quantities ( ) of in air at room temperature. The sensor showed electromotive force (emf) response in the negative direction to changes in the concentration. Furthermore, the emf value varied linearly with the logarithm of the concentration, while it was minimally affected by the water-vapor concentration. The sensing mechanism was shown to be based on the mixed potential at the working electrode through measurements of the polarization curves of and air. The electrolyte was also applied in two single-chamber sensors, wherein and carbon were used as active and inactive electrodes, respectively; these electrodes were attached on the opposite surfaces or on the same surface of the electrolyte. Both single-chamber sensors could exhibit comparable sensitivities, compared to the dual-chamber sensor.