Electrochemical behavior of CoSb3 in sulfuric and oxalic acids over the potential range 0 to 40 V
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The electrochemical behavior of pure Co, pure Sb, and CoSb3 has been investigated over a large anodic potential range (0 to 40 V) in two acids, i.e., oxalic acid or sulfuric acid at different concentrations (0.01 to 1 M). Potentiodynamic polarizations performed on CoSb3 plates reveal the possible formation of a passive layer between 1 and 3 V (vs SCE), on a passivation plateau. The oxidation of CoSb3 at 2 V in sulfuric and oxalic acids results in the growth of an anodic conversion layer. This coating is mainly made of a porous layer of amorphous antimony oxides due to dealloying of CoSb3. In the specific case of oxalic acid, rods of crystallized oxalates are tangled between the oxide sheets.
KeywordsIntermetallics Thin films Anodization Dealloying SEM
The French National Research Agency (ANR) is gratefully acknowledged for financial support of the post-doctoral position of Richard Drevet in the project Nanoskut (ANR-12-PRGE-0008-01).