Effect of 2-Butyne-1,4-diol and ethylene diamine on electrodeposition of Cu from ionic liquid

The effect of additives, 2-Butyne-1,4-diol (BDO) and ethylene diamine (EDA), was investigated on the electrodeposition of Cu from 1-hexyl-3-methylimidazolium trifluoromethanesulfonate ([HMIM]OTF). The results of UV-Vis absorption spectra and Cyclic voltammograms indicate that the reduction potential of Cu shifts to the positive side with the addition of BDO without any changes in the coordination environment of Cu²⁺+. The adsorption of BDO on surface of working electrode results in a change in morphology of the obtained deposit. In the presence of EDA, the coordination environment of Cu²⁺ is changed, suggesting the formation of a new complex by Cu²⁺+ and EDA. The deposition potential shifts to the positive side with addition of EDA. Scanning electron microscope and atomic force microscope tests show that the surface morphology of the obtained deposit is flatter and more granular compared to that without EDA. When BDO and EDA are added into [HMIM]OTF at the same time, the deposition potential still shifts positively and nano-sized grains are obtained.