Electrochemical Hydrogen Sensor with the Titanium/Hydrogen Reference Electrode and High-Temperature Proton Conductor

Abstract

The long-term stability of the electrochemical hydrogen sensor comprised of the proton-conducting solid electrolyte, In-doped CaZrO(3) and the solid reference electrode, titanium/titanium hydride mixture has been investigated. Basic sensing characteristics of the hydrogen sensors for H(2) were very excellent, but the small increment of the voltage of the sensor with time was observed in the long-term stability tests. This voltage drift may be caused by the instability of the solid reference electrode. Especially, the chemical stability of Ti/TiH(2) was examined through the measurement of the formation enthalpy of titanium/hydrogen system. The results showed that the formation enthalpy of hydrogen in titanium was gradually increased and it led to the increase of the reference hydrogen partial pressure. After all, it can be explained this phenomenon causes the small drift of EMF in accordance with Nernst equation.