Water Splitting on Model-Composite La_(0.6)Sr_(0.4)FeO_(3-δ) (LSF) Electrodes in H_2/H_2O Atmosphere

摘要

Mixed conducting cathodes for solid oxide electrolysis cells (SOECs) offer a promising alternative to the nowadays used Ni/YSZ cermet. Here, the water splitting kinetics of mixed conducting perovskite-type La_(0.6)Sr_(0.4)FeO_(3-δ) (LSF) thin film electrodes was investigated in humid reducing atmospheres at 600 - 650°C. Under equilibrium conditions an area specific surface resistance of ca. 15Ωcm~2 was obtained on freshly prepared electrodes. Upon cathodic polarization of more than 20 mV a strong decrease of the surface resistance was observed. This acceleration of the water splitting kinetics was accompanied by the formation of metallic iron particles on the LSF surface, which was observed by means of near-ambient pressure XPS experiments.