Electrochemical properties of ceramic membranes based on SrTi0.5Fe0.5O3−δ in reduced atmosphere

The present work aims at the investigation of the electrochemical properties of SrTi0.5Fe0.5O3−δ as a membrane material for hydrogen production via electrochemical reforming. The dependence of the electrical conductivity on the oxygen partial pressure, as well as the oxygen permeability in the range of 10−20 atm ≤ pO2pO2 ≤ 10−14 atm is examined. The oxygen permeability is measured by an electrochemical method. The dependences of ion current as a function of the electromotive force (EMF) at various temperatures, oxygen partial pressures and the membrane surface conditions (rough and activated by PrOx) are studied. Finally, the values of hydrogen flux at different temperatures are calculated and a long term investigation during 600 h at pO2pO2 = 10−19 atm, T = 1173 K is carried out. According to the present results, the permeation current increases with the increase of temperature, oxygen partial pressure gradient and activation by PrOx. The long term investigation shows that the electrical resistance of the SrTi0.5Fe0.5O3−δ ceramic membrane increases by 10%, possibly due to the formation of micro-domains into the material's volume and the decrease in the grain boundary conductivity, because of the segregation of dopant-rich layers near the grain boundaries.

► The structural and electrochemical properties of SrTi0.5Fe0.5O3−δ are investigated. ► The permeation current increases with the increase of temperature and pO2pO2 gradient. ► The permeation current increases by Pr6O11 activation. ► The long term investigation shows that the electrical resistance increases by 10%.