Enabling extraordinary oxygen reduction reaction activity of dual alkaline earth-substituted perovskite cathodes for intermediate-temperature solid oxide fuel cells

Dual alkaline earth-substituted Pr0.94Ba1-2xSrxCaxCo2O5+delta perovskites are evaluated as potential cathodes for intermediate-temperature solid oxide fuel cells. When incorporating Sr2+ and Ca2+ into the lattice, the phase transformation from tetragonal layered perovskite to simple cubic perovskite can be identified. Benefitting from enhanced electrical conductivity, oxygen surface exchange and ionic diffusion rates, the as-prepared perovskite catalysts demonstrate highly electrocatalytic activity for oxygen reduction reaction. The Pr0.94Ba0.6Sr0.2Ca0.2Co2O5+delta cathode exhibits an area-specific resistance of 0.025 omega cm2 at 700 degrees C, approximately decreased by = 60% relative to the pristine Pr0.94BaCo2O5+delta. It is discovered that Sr2+ and Ca2+ co-substituting lowers the charge transfer energy, as well as oxygen adsorption energy. Furthermore, the Pr0.94Ba0.6Sr0.2Ca0.2Co2O5+delta cathode-based fuel cell delivers a peak power density of 1194 mW cm-2 at 700 degrees C, along with outstanding short-term stability over a period of 160 h. Our results highlight a strategy of dual alkaline earth substitution for rationally designing the perovskite electrocatalysts.

Automated summary

Dual alkaline earth-substituted Pr0.94Ba1-2xSrxCaxCo2O5+delta perovskites are investigated as cathodes for intermediate-temperature solid oxide fuel cells. Incorporating Sr2+ and Ca2+ into the lattice leads to a phase transformation from tetragonal to simple cubic perovskite structure. The perovskite catalysts exhibit enhanced electrocatalytic activity due to improved electrical conductivity, oxygen surface exchange, and ionic diffusion rates. The Pr0.94Ba0.6Sr0.2Ca0.2Co2O5+delta cathode shows reduced area-specific resistance and delivers high power density and stability in fuel cell operation.