Improving oxygen incorporation rate on (La_(0.6)Sr_(0.4))_(0.98)FeO_(3-δ) via Pr_2Ni_(1-x)Cu_xO_(4+δ) surface decoration

摘要

Insufficient electrocatalytic activity for oxygen reduction/evolution in lanthanum strontium ferrite (LSF) perovskites at temperatures below 700 degrees C, limits the utilization of these Co-free oxides as oxygen electrodes for intermediate-temperature solid oxide fuel/electrolysis cells (SOFC/SOEC). Marked performance improvement is here reported by decorating the surface with Pr2Ni1-xCuxO4 catalyst particles. Infiltrating porous LSF electrodes with aqueous nitrates solutions containing Pr, Ni and Cu, targeting the compositions Pr2Ni0.7Cu0.3O4 and Pr2Ni0.6Cu0.4O4, significantly reduces the polarization resistance at 650 degrees C from 0.98 Omega cm(2) to 0.16 Omega cm(2) and 0.13 Omega cm(2) respectively. Electrical Conductivity Relaxation (ECR) measurements reveal that surface exchange rates, expressed by (k(chem)), are much more stable in week long aging experiments for Pr2Ni0.7Cu0.3O4 surface decorated LSF bars compared to the bare LSF. This shows that a Pr2Ni1-xCuxO4 infiltrated porous LSF backbone can be an efficient Co-free oxygen electrode for intermediate-temperature SOFC/SOEC.