Enhanced electrochemical performance of BaZr0.1Ce0.7Y0.1Yb0.1O3−δ electrodes for hydrogen and methane oxidation in solid oxide fuel cells by Pd or Cu0.5Pd0.5 impregnation

The anode material BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) for solid oxide fuel cells (SOFCs) is prepared by solid state reaction method and its chemical compatibility with Y2O3 stabilized ZrO2 (YSZ) is evaluated. The electrochemical performance of the pure and Pd- and Cu0.5Pd0.5-impreganated BZCYYb electrodes is characterized in the temperature range between 650 and 750 °C by AC impedance spectroscopy in H2 and/or CH4 atmospheres, respectively, under the condition of open circuit. It is confirmed that the BZCYYb is chemically compatible with the YSZ at temperatures below 1000 °C. The polarization resistance of the BZCYYb anode in H2 is decreased from 2.08 to 0.51 Ω cm2 as the measuring temperature increases from 650 to 750 °C with an activation energy of 117 kJ mol−1. With Pd- or Cu0.5Pd0.5-impregnation, the polarization resistance of the BZCYYb electrode in H2 is reduced significantly to approximately 0.40 Ω cm2 at 650 °C and 0.12 Ω cm2 at 750 °C. With dry CH4 as the fuel, the polarization resistance of the Pd- and Cu0.5Pd0.5-impregnated BZCYYb anodes is obviously increased below 1.00 Ω cm2 at 650 °C and 0.22 Ω cm2 at 750 °C. Both Pd and Cu0.5Pd0.5 impregnations are equivalently effective in enhancing the electrochemical performance of the BZCYYb anode.

► BZCYYb powder was synthesized by solid reaction method and its chemical compatibility with the YSZ was evaluated.
► Electrochemical performance of the BZCYYB anode was characterized by AC impedance in H2.
► Electrochemical performance of Pd- and Cu0.5Pd0.5-impregnated BZCYYb anodes was characterized by AC impedance in H2 and CH4.
► Improved performance of the BZCYYb anode by Pd- or Cu0.5Pd0.5-impregnation was confirmed.