Electrodeposition of Ni from a high internal phase emulsion (HIPE) template

Porous Ni coatings on electrodes were produced by electrodeposition from a High Internal Phase Emulsion (HIPE) containing the components of the electroplating bath in the aqueous phase. Electroplating from the low conductivity water-in-oil emulsion is attributed to partial phase separation and the creation of interconnected aqueous domains. The resulting porous deposits have an irregular structure characterised by a variety of features, indicative of high local current densities and Ni ion depletion in the aqueous domains through which the metal is growing. The porous Ni coatings produced from HIPE emulsions by electroplating at 5-500 mA cm(-2), showed lower overpotentials for hydrogen evolution than those of deposits produced through the corresponding solid polymer templates (PHIPEs) as well as typical sintered Ni electrodes of similar thickness. while also exhibiting higher surface area utilisation. (C) 2001 Elsevier Science Ltd. All rights reserved.