Physical characterization and electrochemical performance of copper-iron-ceria-YSZ anode-based SOFCs in H₂and methane fuels

Abstract

Thermal instability and poor electrochemical activity of copper-ceria-YSZ anodes at the solid oxide fuel cells (SOFCs) operation temperature (>700 °C) necessitates the use of new strategy to improve the performance of respective anodes for direct hydrocarbon SOFCs. In the present study, iron is incorporated into copper–ceria–YSZ anodes in order to investigate the structural, morphological, and electrochemical properties by using various techniques such as X-ray diffraction, elemental mapping, current–voltage testing, and electrochemical impedance spectroscopy. X-ray diffraction shows that copper promotes the reduction of iron oxide, and formation of cubic phase of copper–iron metals is observed after reduction in H2 at 800 °C. Elemental mapping shows better distribution of metal catalyst inside the pores of copper–ceria–YSZ anodes at 800 °C in the presence of iron. The maximum power densities of copper–ceria–YSZ anodes and copper–iron–ceria–YSZ anodes are observed to be 140 and 195 mW cm−2 in H2 fuel and 70 and 90 mW cm−2 in CH4 fuel at 800 °C. The maximum power density increases with the increase in Cu–Fe metal loading, temperature and with the addition of 1-wt% Pd in copper–iron–ceria–YSZ anodes. The decrease in performance from 125 to 100 mW cm−2 is observed during the exposure of CH4 fuel for 46 h. Electrochemical impedance spectra show an increase in ohmic and total resistance of cell because of sintering and carbon formation, which affects the catalytic activity of anode lowering the performance of SOFC as suggested by post SEM analysis. Copyright © 2015 John Wiley & Sons, Ltd.