Abstract
Rhenium-containing films were grown on gold and platinum after different potentiostatic and potentiodynamic polarizations in the - 0.20 V to 0.70 V range (vs rhe) in aqueous acid perrhenate. Experimental data were obtained using cyclic voltammetry and ellipsometry, from which the thickness and optical indices of the electrodeposited rhenium layer were calculated. Metallic rhenium deposition on gold takes place at potentials within the hydrogen evolution reaction. Rhenium oxide on platinum is formed in the hydrogen adatom potential domain, whereas metallic rhenium is deposited concurrently with the hydrogen adsorption and evolution reactions on the same metal.
Highlights
The electrochemistry of rhenium has been the subject of different studies because of its catalytic properties in fuel cell electrodes and as a coordination compound in radiopharmacy.[1,2,3] The electrodeposition of rhenium species on gold from aqueous perrhenate solutions has been investigated by Horanyi et al.,[4] concluding that metallic rhenium is deposited at potentials within the hydrogen evolution region
To the methodology used for rhenium deposition on gold, the optical indices for platinum were calculated assuming the formation of a single homogeneous film of constant composition and different thicknesses
A composite of metallic rhenium and occluded hydrogen is obtained with a rhenium volumetric fraction of about 30%
Summary
The electrochemistry of rhenium has been the subject of different studies because of its catalytic properties in fuel cell electrodes and as a coordination compound in radiopharmacy.[1,2,3] The electrodeposition of rhenium species on gold from aqueous perrhenate solutions has been investigated by Horanyi et al.,[4] concluding that metallic rhenium is deposited at potentials within the hydrogen evolution region. The nature of the adsorbed layer has not been yet identified.[5] On platinum, on the other hand, some kind of oxygencontaining rhenium species has been detected, probably. In the present work additional information obtained by spectroscopic in situ ellipsometry may contribute to solve the controversy still existing about the nature of the electrodeposited layer both on platinum and on gold ReO2.6 It has been suggested that prior to hydrogen electroadsorption ReO2 adsorption takes place, and after the layer completion, bulk phases of ReO2 and ReO3 can be observed.[7]
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