Discerning the oscillatory electrochemical response during electrodeposition of cobalt in the presence of but-2-yne-1,4-
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ORIGINAL PAPER
Discerning the oscillatory electrochemical response during electrodeposition of cobalt in the presence of but-2-yne-1,4-diol M. Kiruba 1,2 & C. Jeyabharathi 1,2 Received: 5 June 2020 / Revised: 17 June 2020 / Accepted: 18 June 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract We present a new observation of electrochemical oscillation during the reduction of Co2+ 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. Keywords Cobalt . Electrodeposition . Adsorbed hydrogen . Electrochemical oscillation . Hydrogenation . Butynediol
Introduction Oscillatory behavior in electrochemical systems is observed due to the self-organization phenomena at the electrodesolution interface [1–3]. Depending on the system under study, the origin of the electrochemical oscillations involves varied pathways/mechanisms involving anodic dissolution [4], passivation [5], and corrosion of metals and alloys [6, 7]. Passivation due to electrochemical gold oxide formation on gold surface and its chemical removal by chloride ions under diffusion control is one such example for the selforganized system that results in periodic current oscillations under hydrodynamic conditions [8]. Perini et al. [9] observed potential oscillations as a result of the passivation of the Pt sites by CO upon formic acid oxidation and their removal due to self-cleaning processes. Also during the metal electrodeposition, oscillatory behavior has been observed [1, 10] due to Dedication CJ dedicates this contribution to Professor Fritz Scholz on the occasion of his 65th birthday. * C. Jeyabharathi [email protected] 1
Electroplating and Metal Finishing Division, CSIR-Central Electrochemical Research Institute, Karaikudi, Tamil Nadu 630003, India
2
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
inhibitory effect of certain additives and passivation by hydroxide precipitation at very high current densities, for example, zinc [11, 12], copper [13], cadmium [14], and Sn-Co alloy [15] electrodeposition. Generally, additives have been used in metal electrodeposition to achieve uniform, compact, and bright coatings. The butynediol is an additive that has been used as class II brightener in electrodeposition of metals and alloys [16–18]. During the electrodeposition process, Rogers et al. [17] reported that butynediol undergoes electroreduction to butenediol/butanediol on Ni. Later studies showed that the hydrogenation of butynediol took place through a chemical catalytic mechanism under hydrogen evolution condition during the elect
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