Stabilizing Nanostructured Solid Oxide Fuel Cell Cathode with Atomic Layer Deposition

We demonstrate that the highly active but unstable nanostructured intermediate-temperature solid oxide fuel cell cathode, La_0.6Sr_0.4CoO_3‑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