Development of electrode morphologies of interest in electrocatalysis. Part I: Electrodeposited porous nickel electrodes

Pure nickel electrodeposits with macropores were prepared from electrolytic solutions of 0.2 M NiCl2 and NH4Cl with concentrations varying between 0.25 and 4 M. The effects of the electrodeposition current density and the NH4Cl concentration on the surface morphology were determined. Surface area, faradaic efficiency and fractal dimension of the cross-section of the electrodeposits were evaluated also. From these results, it was concluded that highly porous metallic matrices can be obtained, with very high roughness factors and excellent mechanical resistance, yet at very high apparent current densities of electrodeposition (5 A cm(-2)). The use of this type of electrodeposition bath is suggested for the preparation of Raney-Nickel electrodes, in order to improve the accessibility of reactants to the electrode surface. (C) 2000 Elsevier Science Ltd. All rights reserved.