Polarization study of Fe|BaCe<inf>0.5</inf>Zr<inf>0.3</inf>Y<inf>0.08</inf>Yb<inf>0.08</inf>Cu<inf>0.04</inf>O<inf>3-δ</inf>|Fe electrochemical cells in wet H<inf>2</inf> atmosphere

Abstract

In the present work, the steady-state current-overpotential characteristics of the Fe|BaCe<inf>0.5</inf>Zr<inf>0.3</inf>Y<inf>0.08</inf>Yb<inf>0.08</inf>Cu<inf>0.04</inf>O<inf>3-δ</inf>|Fe interface as a function of the gas phase composition and temperature are investigated. To this purpose a BaCe<inf>0.5</inf>Zr<inf>0.3</inf>Y<inf>0.08</inf>Yb<inf>0.08</inf>Cu<inf>0.04</inf>O<inf>3-δ</inf> dense ceramic material is successfully synthesized by solid state synthesis and sintered at 1400°C. Then its crystal structure, ceramic and electrical properties are investigated. It is found that the ceramic has a high relative density (more than 90%) and acceptable proton conductivity (1.5 and 6.8mScm-1 at 500 and 900°C, respectively). On the as prepared BaCe<inf>0.5</inf>Zr<inf>0.3</inf>Y<inf>0.08</inf>Yb<inf>0.08</inf>Cu<inf>0.04</inf>O<inf>3-δ</inf> electrolyte disk, three thin Fe porous layers are deposited by painting on both sides (three electrode system), which is then immersed in a tubular single-chamber continuous electrochemical reactor.The polarization measurements are carried out in the temperature range between 500 and 700°C and at three different H<inf>2</inf>/He wet (3% steam) compositions. The apparent anodic and cathodic charge transfer coefficients (Tafel region) are found to be: α <inf> a </inf>=α <inf> c </inf>=0.8, while the apparent activation energy is calculated to be approximately 0.55±0.05eV. It is also found that by increasing the hydrogen concentration the current density increases, especially at higher temperature values. © 2015 Hydrogen Energy Publications, LLC.