Naslov
The electrochemical behaviour of nanocrystalline nickel : a comparison with polycrystalline nickel under the same experimental condition

Autori
Grubač, Zoran ; Petrović, Željka ; Katić, Jozefina ; Metikoš-Huković, Mirjana ; Babić, Ranko

Izvornik
Journal of electroanalytical chemistry (1572-6657) 645 (2010), 2; 87-93

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
nanocrystalline nickel; quartz crystal nickel electrode; alfa-; beta-Ni(OH)2; passivity; semiconducting properties; electrochemical ac/dc techniques

Sažetak
The main objective of this work was to study the effect of nanocrystalline (nc) grain size on the electrochemical behaviour of solid-state and interfacial processes in the Ni | oxide film | electrolyte system inside the potential region between hydrogen and oxygen evolution. Nc-Ni thin films were deposited by magnetron sputtering onto alumina ceramic substrates. The study was performed in a pH 8.4 borate buffer solution by using in situ voltammetry, electrochemical impedance spectroscopy (EIS), and electrochemical quartz crystal nanobalance (EQCN) methods. Both the significant increase in the charge storage ability during anodic polarization inside the potential region of Ni(OH)2 formation and a shift of the onset potential for hydrogen evolution to the positive potentials due to the small grain size and the high volume fraction of grain boundaries in comparison to polycrystalline Ni have been observed. The passive film properties were discussed in terms of the point defect model and the Mott-Schottky theory. Inside the potential region of Ni(II) oxidation state, the passive film behaves as a p-type semiconductor. Its protection properties decrease with increasing anodic potential, especially at potential values corresponding to the Ni(OH)2 to NiOOH transition.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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