|Title||Oxygen Reduction and Evolution on Perovskite Thin Films Made with Pulsed Laser Deposition|
|Publication Type||Book Chapter|
|Year of Publication||1995|
|Authors||Kathryn A Striebel, Charles Z Deng, Shi-Jie Wen, Elton J Cairns|
|Editor||Radoslav R Adzic, Fred C Anson, Kim Kinoshita|
|Book Title||Proceedings of the Symposium on Oxygen Electrochemistry|
|Publisher||The Electrochemical Society, Inc.|
The rates of oxygen reduction and evolution on thin films of La0.6Ca0.4CoO3, La0.6Ca0.4MnO3 and La0.5Sr0.5FeO3, prepared with pulsed laser deposition, were measured with the RRDE technique in 0.1M KOH. The order of activity was La0.6Ca0.4MnO3 > La0.5Sr0.5FeO3 > La0.6Ca0.4CoO3 with Tafel slopes of about 90 mV/decade. Oxygen reduction proceeds mostly through the direct 4e-pathway on La0.6Ca0.4CoO3 with k1=5.6 k2. The order of activity for oxygen evolution was La0.6Ca0.4MnO3 > La0.6Ca0.4CoO3 > La0.5Sr0.5FeO3 with Tafel slopes of 60mV/decade. The La0.6Ca0.4MnO3 film showed a slow increase in porosity with measurement time and the La0.5Sr0.5FeO3 film was unstable at E < -0.2 V vs. Hg/HgO. La0.6Ca0.4CoO3 was active for H2O2 reduction and oxidation. A partially-carbon-coated La0.6Ca0.4CoO3 film showed higher currents for oxygen reduction than the bare film, due to oxygen reduction on the carbon and further reaction on the neighboring La0.6Ca0.4CoO3.