Study on the Electrodeposition of Hydroxides in Hydrated Perchlorate + Organic Solvent Systems Using EQCM

The electrochemical quartz crystal microbalance (EQCM) method was used to quantitatively examine the precipitation of LiOH (or NaOH) onto a gold electrode at potentials negative to ca −0.8 V (vs SCE) during the cathodic sweep reduction of dissolved oxygen and coexisting water in acetone, DMF, DMSO, C2H5OH, or CH3OH containing hydrated perchlorate, as a result of the poor solubility of electrogenerated hydroxide in the nonaqueous medium. In contrast, the EQCM response indicative of precipitate adherence was negligibly small, when tetrabutyl ammonium bromide was used as the supporting electrolyte. Effects of electrolyte and its concentration, solvent, and water content on the electrodeposition of hydroxide were discussed, and the electrode-collection efficiency for the precipitate was evaluated.