Electrodeposition of cobalt from cobalt chloride-N-(n-butyl)pyridinium chloride molten salt

Abstract

A molten salt system of CoCl2-N-(n-butyl)pyridinium chloride (BPC) having melting point <80°C has been developed over a wide composition range (1:2 to 1:1 mole ratio CoCl2-BPC) and the electrodeposition of cobalt has been carried out by constant current and constant potential methods at 110°C. Cobalt cannot be deposited from a CoCl2-BPC melt containing BPC concentration higher than the mole ratio of 1:2, whereas it can be deposited from BPC concentration lower than the mole ratio of 1:2. The deposition reaction mechanisms of cobalt in the CoCl 2-BPC molten bath are revealed by electrochemical analysis. The experimental Tafel slope of 62 mV dec-1 and the calculated transfer coefficient (αc) of 1 (one) suggest that the rate determining step is a chemical reaction involving the release of the complexing agents occurring after first charge transfer step. X-ray diffractometer and scanning electron microscope have been used to investigate the influence of electrodeposition conditions and the morphology of the electrodeposited layers. The cathodic current efficiency for the deposition of cobalt is about 98%.

Publication Title

Indian Journal of Chemical Technology

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