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|Title:||Electrocatalytic characterization of new La1-xSrxCoO3 films on Pt for use as oxygen anode in alkaline solutions|
|Authors:||Singh, R N|
|Abstract:||Pure and Sr-substituted lanthanum cobaltate films have been prepared on Pt by a sol-gel derived route and their physicochemical and electrochemical properties investigated using XRD, IR, cyclic voltammetriy (CV), Tafel-polarization and impedance techniques. The films have been obtained by coating a thick colloidal solution formed by peptization of freshly prepared metal carbonate precipitate in glacial acetic acid and subsequent drying and sintering at 650°C for 2 h. The substitution of La by Sr in the perovskite lattice does not indicate any significant influence on the rate of O2 evolution reaction (OER) in 1M KOH. Values of the Tafel slope and the order for the reaction have been observed to be ~2.303RT/F and ~1, respectively, regardless of the nature of the oxide catalyst. The apparent electrochemical activation energy (ΔHel#) decreases linearly with increasing potential across the oxide/1 M KOH interface. Values of the entropy of activation (ΔS#) for the OER are highly negative. Based on electrode kinetic results, the OER is considered to proceed with the formation of adsorbed OH radical as the intermediate in a fast step followed by its electrochemical interaction to yield physisorbed H2O2 in the slow step.|
|Appears in Collections:||IJC-A Vol.40A(10) [October 2001]|
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