Electrodeposition of Cobalt from Aqueous Chloride Solutions

Abstract

Electrodeposition of cobalt in aqueous chloride solutions has been studied by means of cyclic voltammetry and potentiostatic current-time transient techniques on rotating nickel disk electrodes. The electrocrystallization of cobalt is via a three-dimensional progressive nucleation and crystal growth mechanism under interfacial electron transfer/mass transfer control. As the deposition proceeds, concentration polarization becomes increasingly important after the nickel disk electrode is nearly or fully covered by cobalt crystallites. However, as the bulk concentration of Co 2 § ions increases, the kinetics of the nucleation and crystal growth is increasingly dominated by interfacial electron transfer. It has also been found that in the electrodeposition process influenced by both interfacial/mass transfer p~ocesses, the electrode kinetics parameters can be obtained by analyzing the cathodic current responses of the reverse sweeps on the voltammetric curves. The measured Tafel slope of 29 mV and diffusion coefficient of 0.53 • l0 -9 cm 2 s -1 are in good agreement with the values reported in the literature.

In Situ Stress Measurements during Cobalt Electrodeposition on (111)-Textured Au

“…14 The accompanying stress signature shows that prior to Co reduction, there is a slight increase in the tensile direction owing to electrocapillarity as well as the desorption of ClO 4 − from the Au surface. 60 The latter contribution is particularly relevant as the potential approaches the potential of zero charge (PZC), which is −0.2 V for Au at this pH and electrolyte.…”

“…14 In the latter case, the 14% strain in the Co layer required to maintain registry with the underlying Au is at least partially stabilized by adsorbed SCN − on the Co monolayer. 14 Co upd has also been reported from NH 4 Cl electrolyte (pH 9.5) where the Co 2+ in solution is present as the [Co(NH 3 ) 5 …”

“…The use of electrodeposited Co-based materials has attracted much attention over the past several decades owing in part to their interesting magnetic 1-3 and catalytic properties. [4][5][6][7][8][9][10][11] These properties are largely dependent upon the structure and morphology of the electrodeposit, which in the case of cobalt can vary dramatically with overpotential, electrolyte pH, and the presence of strongly adsorbing anions. 2,[12][13][14][15][16] …”

In-situ magnetization measurements and ex-situ morphological analysis of electrodeposited cobalt onto chemical vapor deposition graphene/SiO2/Si

“…Most studies about cobalt electrodeposition have been performed on a variety of substrates, such as carbon-based materials [1][2][3][4], gold [5,6], nickel [7], copper [8] and platinum [9], as working electrodes (WE). Carbonbased substrates have frequently been used as electrodes because they are inert surfaces that result in low hydrogen formation at high negative potential [10].…”

Cobalt electrodeposition onto highly oriented pyrolytic graphite (HOPG) electrode from ammonium sulfate solutions

“…Most of the Co electrodeposition studies have been performed onto carbon electrodes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and some others onto stainless steel, 18,19 gold, [20][21][22] nickel, 23 copper 24 and platinum 25 electrodes. Probably, carbon electrodes are the preferred substrates because they offer an inert surface in where it is possible to study the nucleation and growth process neglecting the metal-metal interaction.…”