Discerning the oscillatory electrochemical response during electrodeposition of cobalt in the presence of but-2-yne-1,4-diol

We present a new observation of electrochemical oscillation during the reduction of Co 2+ from sulfate solution in the presence of but-2-yne-1,4-diol (butynediol) as an additive. Cyclic voltammetry, hydrodynamic voltammetry at galvanostatic condition, and electrochemical impedance spectroscopic studies suggest that the electrochemical oscillation observed was a relaxation type and was the manifestation of adsorbed hydrogen formation by electrochemical reduction of protons on cobalt and their chemical removal by semi-hydrogenation of butynediol to butenediol during the initial stages of electrodeposition. Graphical abstract