Electrodeposition mechanism of aluminium from aluminium chloride-N-(n-butyl)pyridinium chloride room temperature molten salt

Abstract

<span style="font-size:12.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">Electrodeposition of aluminium has been carried out by controlled-current and controlled-potential methods from acidic aluminum(III) chloride-N-(<i>n</i>-butyl)pyridinium chloride (BPC) molten bath at room temperature. The electrodeposition of aluminium from acidic AlCl₃-BPC melt occurs via instantaneous nucleation mechanism in the very initial stage of the crystal growth. The deposition reaction mechanisms of aluminium in the acidic AlCl₃-BPC molten bath are revealed by electrochemical analysis. The experimental Tafel slope of 20 mV dec^-1 and the calculated transfer coefficient (α_c) of 3 suggest that the rate determining step is a chemical reaction involving the release of the complexing agents via three consecutive single electron transfer steps. The influence of various conditions on electrodeposition and the morphology of the electrodeposited layers have been investigated by X-ray diffractometry and scanning electron microscopy. On increasing the current density smaller particle size and better adhesiveness of the electrodeposited layers have been obtained. The cathodic current efficiency for the deposition of Aluminium is about 99.8%.</span>