Electrochemical properties of ceramic membranes based on SrTi0.5Fe0.5O3-delta in reduced atmosphere

Abstract

The present work aims at the investigation of the electrochemical properties of SrTi0.5Fe0.5O3-delta 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 <= po(2) <= 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 po(2) = 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-delta 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. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.