Electrodeposition of palladium and adsorption of palladium chloride onto solid electrodes from room temperature molten salts

The electrodeposition of palladium onto various electrode surfaces was examined in room temperature AlCl[sub 3]-MEIC molten salts with AlCl[sub 3] mole fractions, N, from 0.33 < N < 0.5 (basic melts) to 0.5 < N < 0.67 (acidic melts) and at N = 0.5 (neutral melt). The behavior of palladiu...

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Bibliographic Details
Published in:Journal of the Electrochemical Society 1994-04, Vol.141 (4), p.1000-1005
Main Authors: DE LONG, H. C, WILKES, J. S, CARLIN, R. T
Format: Article
Language:English
Subjects:
250903 - Energy Storage- Batteries- Materials, Components, & Auxiliaries
ADSORPTION
ALUMINIUM CHLORIDES
ALUMINIUM COMPOUNDS
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
DEPOSITION
ELECTRIC BATTERIES
ELECTROCHEMICAL CELLS
ELECTROCHEMISTRY
ELECTRODEPOSITION
ELECTRODES
ELECTROLYSIS
ELEMENTS
ENERGY STORAGE
Exact sciences and technology
General and physical chemistry
HALIDES
HALOGEN COMPOUNDS
LYSIS
METALS
PALLADIUM
PALLADIUM CHLORIDES
PALLADIUM COMPOUNDS
PLATINUM METALS
REDOX POTENTIAL
SORPTION
Study of interfaces
SURFACE COATING
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
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Summary:The electrodeposition of palladium onto various electrode surfaces was examined in room temperature AlCl[sub 3]-MEIC molten salts with AlCl[sub 3] mole fractions, N, from 0.33 < N < 0.5 (basic melts) to 0.5 < N < 0.67 (acidic melts) and at N = 0.5 (neutral melt). The behavior of palladium electrodeposition was markedly dependent on the mole fraction of AlCl[sub 3] in the molten salts. The palladium reduction potential shifts approximately +2.0 V when the melt is changed from basic to acidic. Nucleation overpotentials were evident in basic melts, and to a lesser extent in acidic and neutral melts. In acidic melts, the reduction of the sparingly soluble palladium complex displays characteristics distinctive of an adsorption phenomenon, while the oxidation process shows considerable broadening. Oxidation of a palladium electrode in an N = 0.55 acidic melt produces an insoluble palladium chloride layer (approximately a monolayer) on the electrode surface which protects the underlying metal from further oxidation. Reduction of this surface anchored palladium chloride layer is rapid and provides a high cathodic current density. This behavior in acidic melts in pointedly different from the reduction process in a basic melt where the reduction of the soluble palladium chloro complex exhibits a diffusion wave with nucleation effects.
ISSN:0013-4651
1945-7111
DOI:10.1149/1.2054831