We demonstrate that the highly active but unstable nanostructured intermediate-temperature solid oxide fuel cell cathode, La0.6Sr0.4CoO3-δ (LSCo), can retain its high oxygen reduction reaction (ORR) activity with exceptional stability for 4000 h at 700 °C by overcoating its surfaces with a conformal layer of nanoscale ZrO2 films through atomic layer deposition (ALD). The benefits from the presence of the nanoscale ALD-ZrO2 overcoats are remarkable: a factor of 19 and 18 reduction in polarization area-specific resistance and degradation rate over the pristine sample, respectively. The unique multifunctionality of the ALD-derived nanoscaled ZrO2 overcoats, that is, possessing porosity for O2 access to LSCo, conducting both electrons and oxide-ions, confining thermal growth of LSCo nanoparticles, and suppressing surface Sr-segregation is deemed the key enabler for the observed stable and active nanostructured cathode.
We report that the long-term stability of a conventional mixed oxide-ion and electron conducting solid oxide fuel cell cathode, La 0.6 Sr 0.4 Fe 0.8 Co 0.2 O 3−δ -Gd 0.2 Ce 0.8 O 1.9 (LSCF-GDC) composite, can be markedly improved by functionalizing its surfaces with a conformal layer of nanoscale ZrO 2 films through atomic layer deposition (ALD). Over a >1100 h testing at 800 °C, the overcoated LSCF-GDC cathode exhibited respective polarization and ohmic area-specific-resistances 3 and 1.5 times lower than the pristine sample, whereas the pristine LSCF-GDC cathode degraded at a rate 4 times faster than the overcoated one. The multifunctionality of porosity, mixed conductivity, and suppressed Srenrichment enabled by the nanoscaled ALD-ZrO 2 overcoats are attributed to the performance retention observed for the overcoated cathode.
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