Abstract

AREMO, B.; ADEOYE, M.O.  and  OBIOH, I. B.. Potentiostatic Co-deposition of Nickel and Graphite Using a Composite Counter Electrode. Port. Electrochim. Acta [online]. 2019, vol.37, n.5, pp.295-305. ISSN 0872-1904.  https://doi.org/10.4152/pea.201905295.

Nickel and graphite were potentiostatically co-deposited using a nickel-graphite composite counter electrode (HCE) with tunable-friability. Graphite electrodes were produced at densities of 0.920, 1.026 and 1.188 g/cm³, and their suitability for constitution into HCE was assessed. The surface area of the nickel component was varied from 100% to about 60% and 30 %, and combined with the graphite electrode, to form HCE, designated as triplet, doublet and singlet, respectively. Deposition was done for about 8 hours in 1 M NiSO_4, using the different HCE constitutions, an Ag/AgCl reference electrode and a custom deposition head which served as working electrode. The mechanism of graphite electrode unraveling was observed to be the formation of oxygen and CO_2, due to oxidation reactions at HCE. The graphite electrode with a density of 0.920 g/cm³ was selected for HCE, due to its extensive surface porosity, a characteristic determined as favorable to the mechanism of electrode unraveling. Co-deposition of graphite with nickel was observed to increase as the nickel surface area was reduced from triplet to singlet. SEM micrographs show partially and fully embedded graphite particles in the nickel matrix, while the presence of nickel and graphite was affirmed.

Keywords : electrodeposition; nickel; graphite and optical microscopy.

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