ELECTROCATALYTIC BEHAVIOR OF NONEQUILIBRIUM BCC NICKEL

Citation
T. Benameur et al., ELECTROCATALYTIC BEHAVIOR OF NONEQUILIBRIUM BCC NICKEL, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 182, 1994, pp. 1145-1149
Citations number
14
Categorie Soggetti
Material Science
ISSN journal
09215093
Volume
182
Year of publication
1994
Pages
1145 - 1149
Database
ISI
SICI code
0921-5093(1994)182:<1145:EBONBN>2.0.ZU;2-B
Abstract
We report on the electrocatalytic activity for the hydrogen evolution reaction (HER) on non-equilibrium b.c.c. nickel electrodes in a concen trated alkaline solution (30 wt.% NaOH). These electrodes were prepare d by mechanical alloying a mixture of nickel and aluminum powders, fol lowed by a leaching treatment. Transmission electron microscopy observ ations and X-ray diffraction patterns show the transformation of the p ure elemental powders to a nanocrystalline phase with a B2-type struct ure. After being treated with 20 wt.% KOH at 70-degrees-C, nearly all the aluminum atoms were removed and a porous b.c.c. Raney nickel was o btained. It was found that the thermodynamic potential of Ni/Ni2+ was 23 mV lower on the metastable b.c.c. nickel than that on the f.c.c. ni ckel electrode. The analysis of the HER kinetic parameters indicates a lower activity of the b.c.c. nickel, when compared with that of the f .c.c. Raney nickel catalyst. Both b.c.c. and f.c.c. nickel catalysts s how a Tafel slope of about 120 mV decade-1, but a lower roughness fact or of the b.c.c. nickel surface was deduced from the coulometric measu rements.