Kinetic study of the cobalt electrodeposition onto glassy carbon electrode from ammonium sulfate solutions

Abstract

We carried out an electrochemical study of the cobalt electrodeposition onto glassy carbon electrode from an aqueous solution containing 10-2 M of CoSO4 + 1 M (NH4)2SO4 at natural pH 4.5. The potentiostatic study indicated a progressive 3D nucleation and growth during the deposition process. The average diffusion coefficient calculated for this system was 2.65 X 10-6 cm² s-1 while the ΔG for the formation of stable nucleus was 6.50 X 10-20 J/nuclei. The scanning electron microscopy images indicated the formation of small and homogeneous nucleus onto GCE of approximately 300 nm

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

“…In previous work it was found that, under the experimental conditions used in this work, the predominant chemical species is a cobalt sulfate pentaquo complex [Co(SO 4 17 It was suggested that the existence of free electrons through sulfate group allows a faster adsorption process on the electrode surface.…”

“…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.…”

“…As a transition from instantaneous to progressive nucleation would seem impossible, this may be indicative of the presence of other contributions to the overall current during the early stages of the cobalt deposition process (t/t m >1) apart from the 3D nucleation contribution. 17,21 Rios-Reyes et al have suggested that for the cobalt electrodeposition case the additional contribution is due to the proton reduction process.…”

Toward uniform electrodeposition of magnetic Co-W mesowires arrays: direct versus pulse current deposition

“…For our simulations we used a value of apparent diffusion coefficient for Co citrate complexes of 7.9·10 -7 cm 2 s -1 [37,38], i.e. the diffusion coefficient of cobalt due to complexation is 3 times lower than that reported in the literature for Co(II) in sulfate-ammonia solutions [39]. Also, the partial blocking of electrode surface by intermediates may have an influence on the apparent value of the diffusion coefficient [38].…”

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

“…Cobalt electrodeposition on highly oriented pyrolytic graphite (HOPG) [1,4] and glassy carbon [2,11] substrates has been studied. Specifically, Grujicic and Pesic [2] published a study on cobalt nucleation mechanisms on a glassy carbon electrode starting from different ammonium sulphate aqueous solutions and using different techniques, such as cyclic voltammetry and chronoamperometry.…”