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Nanoscale Probing of Voltage Activated Oxygen Reduction/Evolution Reactions in Nanopatterned (La x Sr 1‐ x )CoO 3‐ δ Cathodes
Author(s) -
Leonard Donovan N.,
Kumar Amit,
Jesse Stephen,
Biegalski Michael D.,
Christen Hans M.,
Mutoro Eva,
Crumlin Ethan J.,
ShaoHorn Yang,
Kalinin Sergei V.,
Borisevich Albina Y.
Publication year - 2013
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201200681
Subject(s) - materials science , electrochemistry , transmission electron microscopy , nanoscopic scale , electron energy loss spectroscopy , scanning electron microscope , oxygen evolution , biasing , oxygen , analytical chemistry (journal) , scanning transmission electron microscopy , spectroscopy , ion , nanotechnology , chemical physics , electrode , chemical engineering , voltage , chemistry , composite material , physics , organic chemistry , quantum mechanics , chromatography , engineering
Bias‐dependent mechanisms of reversible and irreversible electrochemical processes on a (La 0.5 Sr 0.5 ) 2 CoO 4±δ modified (La x Sr 1‐x )CoO 3 ‐ surface are studied using dynamic electrochemical strain microscopy (D‐ESM). The reversible oxygen reduction/evolution process is activated at voltages as low as 3–4 V and the degree of transformation increases linearly with applied bias. The irreversible processes associated with static surface deformation become apparent above 10–12 V. Post‐mortem focused‐ion milling combined with atomic resolution scanning transmission electron microscopy and electron energy loss spectroscopy is used to establish the mechanisms of irreversible transformations and attribute it to amorphization of the top layer of material. These studies both establish the framework for probing irreversible electrochemical processes in solids and illustrate rich spectrum of electrochemical transformations underpinning electrocatalytic activity in cobaltites.