Effect of nicotinic acid additives on the electrodeposition of Al-Mn alloy from AlCl3-based ionic liquids

The effects of nicotinic acid (NA) on the electrodeposition of Al-Mn alloy have been investigated in aluminum chloride-1-butyl-3-methylimidazolium ionic liquids (AlCl3-BMIC) containing 0.15 mol center dot L-1 MnCl2 (AlCl3-BMIC-MnCl2). The electrochemical behaviors of the AlCl3-BMIC-MnCl2 electrolyte have been studied here using cyclic voltammetry and potentiodynamic polarization. The addition of NA obviously increased the nucleation overpotential of Al-Mn alloy and inhibited the reduction reaction of Al(III) and Mn(II). The resultant surface morphologies, composition, and roughness of the Al-Mn alloy coating were revealed by scanning electron microscopy (SEM), transmission electron microscope (TEM), and atomic force microscopy (AFM). It was found that these additives strongly affect the morphology, composition, roughness, and crystal structure of the Al-Mn alloy coating. With the addition of NA, the content of Mn decreased, and Al-Mn alloy coatings became more uniform and smoother. The crystal structure of Al-Mn coatings was also examined by X-ray diffraction (XRD), where it was found that the phase composition of the deposits depends on the quantities of additives. For electrolyte containing little or no NA additives, the resulting alloy is amorphous structure. With NA additives up to 6 center dot mmol L-1, the Al-Mn coating changed into a mixture phase of amorphous and crystalline structure.

Automated summary

This study investigates the effects of nicotinic acid (NA) on the electrodeposition of Al-Mn alloy in aluminum chloride-1-butyl-3-methylimidazolium ionic liquids. It is found that the addition of NA increases the nucleation overpotential of Al-Mn alloy and inhibits the reduction reaction of Al(III) and Mn(II). The morphology, composition, roughness, and crystal structure of the alloy coating are strongly affected by the presence of NA.