The long term stability of the titanium/hydrogen system as the solid reference electrode in high-temperature proton conductor-based hydrogen sensors

The electrochemical hydrogen sensor comprised of the high temperature proton conductor and the solid reference material of Ti/TiH2 mixture showed the good sensing characteristics at elevated temperatures. However, in the long run, the EMF drift of about 0.2-0.3 mV/h was observed at 973 K. It is thought that the raise of EMF is due to the increase of the reference hydrogen pressure and the lack of the stability of the solid reference material is very critical to cause this phenomenon. In the present study, the long term stability of the solid reference material is investigated by EMF measurement with time.