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Nucleation and Growth of Nickel Deposit on Carbon Microdiscs

The electrocrystallization of nanostructured metallic particles is an area of considerable interest, from both fundamental and practical standpoint with application to several areas such as electroplating, microelectronics, nano-pattering and electrocatalysis. Electrochemical aspects of the initial stage of electrocrystallization of nanostructured nickel were studied in a deaerated 0.14 mol dm^-3 NiCl_2 solution on an assembly of carbon fibres microdisc electrodes randomly distributed inside the matrix of a non-conducting polymer using cyclic voltammetry, chronoamperometry, and optical microscopy. In the investigated potential range the kinetics of nickel electrocrystallization follows 3D-progressive nucleation under the diffusion controlled growth. Relevant kinetic parameters such as the number of nuclei, the nucleation rate, and the diffusion coefficient were calculated. The electrocatalytic performance of the nanostructured nickel layers for the hydrogen evolution reaction has been investigated using dc-polarization and ac-impedance spectroscopy techniques. The obtained results demonstrate a superior electrocatalytic activity of the nanostructured Ni layer relative to the bulk polycrystalline Ni.

Nickel; Electrocrystallization; Carbon fibre microdiscs; 3D progressive nucleation.

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