High surface electron-proton mixed conduction at medium temperature of c-axis oriented BaCe0.7Ru0.1Y0.2O3-δ thin film

Electrochemical reaction-based solid oxide fuel cells (SOFCs), which operate at a medium temperature range from 300 to 600 degrees C, are expected to be a new renewable energy source. The performance of their electrochemical reactions for SOFC anode and cathode electrode membranes can be enhanced using electron-ion mixed conductor material. To realize a practical anode electrode film for SOFCs, c-axis oriented BaCe0.7Ru0.1Y0.2O3-delta (BCRY) thin films were prepared on an MgO (100) substrate by RF magnetron sputtering. The oxygen vacancy concentration in the BCRY thin films was quantitatively evaluated by X-ray absorption spectroscopy and defect chemical analysis. Proton conductivity was proven from the O 1 s photoemission spectrum showing an OH- peak formed on the oxygen ion sites. Electron conductivity was proven from the small density-of-state at the Fermi level (EF) and the energy difference between the top of the valence band and the EF, which is close to the activation energy of the conductivity. The wet-annealed BCRY thin film, which exhibits surface electron-proton mixed conductivity of more than similar to 10-3 S cm-1 at 300 degrees C, can be applied as a practical anode electrode film for SOFC operating in the medium temperature range.