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Probing Bias‐Dependent Electrochemical Gas–Solid Reactions in (La x Sr 1– x )CoO 3– δ Cathode Materials
Author(s) -
Kumar Amit,
Ciucci Francesco,
Leonard Donovan,
Jesse Stephen,
Biegalski Mike,
Christen Hans,
Mutoro Eva,
Crumlin Ethan,
ShaoHorn Yang,
Borisevich Albina,
Kalinin Sergei V.
Publication year - 2013
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201202401
Subject(s) - electrochemistry , materials science , oxygen evolution , ionic bonding , biasing , electrode , analytical chemistry (journal) , reactivity (psychology) , cathode , voltage , chemistry , ion , physics , medicine , alternative medicine , organic chemistry , quantum mechanics , chromatography , pathology
Spatial variability of bias‐dependent electrochemical processes on a (La 0.5 Sr 0.5 ) 2 CoO 4± δ modified (La x Sr 1– x )CoO 3–δ surface is studied using first‐order reversal curve method in electrochemical strain microscopy (ESM). The oxygen reduction/evolution reaction (ORR/OER) is activated at voltages as low as 3–4 V with respect to bottom electrode. The degree of bias‐induced transformation as quantified by ESM hysteresis loop area increases with applied bias. The variability of electrochemical activity is explored using correlation analysis and the ORR/OER is shown to be activated in grains at relatively low biases, but the final reaction rate is relatively small. At the same time, at grain boundaries, the onset of reaction process corresponds to larger voltages, but limiting reactivity is much higher. The reaction mechanism in ESM of mixed electronic‐ionic conductor is further analyzed. These studies both establish the framework for probing bias‐dependent electrochemical processes in solids and demonstrate rich spectrum of electrochemical transformations underpinning catalytic activity in cobaltites.