Oxygen evolution on perovskite-type cobaltite anodes: an assessment of materials science-related aspects

authors	Kovalevsky, AV; Sviridov, DV; Kharton, VV; Naumovich, EN; Frade, JR
editors	Vilarinho, PM
nationality	International
journal	ADVANCED MATERIALS FORUM III, PTS 1 AND 2
author keywords	oxygen evolution; electrochemical activity; perovskite; oxygen deficiency; electronic conductivity; cobaltite
keywords	OXIDES
abstract	Ceramic anodes, made of perovskite-type rare-earth and strontium cobaltites substituted in both sublattices, exhibit a high electrocatalytic activity towards oxygen evolution in alkaline media. This work analyzes the relationships between cation composition, defect structure, electronic conductivity and electrochemical performance for a wide group of perovskite-like cobaltites, including Ln(1-y)A(y)CoO(3-delta) (Ln= Pr, Nd, Sm; A= Sr, Ca; y= 0-0.4), La1-x-ySrxBiyCoO3-delta (x= 0-0.6, y= 0-0.1), La0.7-xSr0.3CoO3-delta (x= 0-0.10), Sr1-xBaxCoO3-delta (x= 0.1-0.2) and SrCo1-yMyO3-delta (M=Fe, Ni, Ti, Cu; y= 0.1-0.6). The materials were prepared by the standard ceramic technique and characterized employing XRD, TGA, iodometric titration, and total conductivity measurements. A relatively high electrochemical performance in alkaline solutions was observed for (La,Sr)CoO3-based compositions with a moderate A-site deficiency. For SrCoO3-based materials, an increase in the oxygen evolution rate was found when co-substituting cobalt with several transition metal cations, such as Fe3+/4+ and Cu2+/3+. The results show that, in general, the key composition-related factors influencing electrochemical activity in alkaline media include the oxygen vacancy concentration, the average positive charge density in the crystal lattice, and possible blocking of active sites on the electrode surface.
publisher	TRANS TECH PUBLICATIONS LTD
issn	0255-5476
year published	2006
volume	514-516
beginning page	377
ending page	381
web of science category	Materials Science, Multidisciplinary
subject category	Materials Science
unique article identifier	WOS:000238056400077