Morphology and Composition of Electrodeposited Cobalt‐Zinc Alloys and the Influence of Boric Acid

Abstract

The morphology and composition of cobalt-zinc alloys electrodeposited on a Pt rotating disk electrode were investi-gated. Three unique morphologies have been identified by scanning electron microscopy and the composition of each characterized by solid-state stripping voltammetry. The effect of boric acid on the morphology of the surface films was also investigated. The results indicate that addition ofboric acid to the plating bath increases the nucleation density of the deposit and increases the content of Zn in the alloy. The current efficiency for the deposition process is also enhanced in the presence of boric acid. These effects have been attributed to the adsorptive interactions of boric acid at the electrode surface. The anqmalous electrodeposition f Ni-Zn and Co-Zn al-loys with controlled morphology and composition has been the subject of many studies due to the improved cor-rosion resistance and catalytic activity (1-7, 13). These two completely different functions of the alloy require very dif-ferent morphologies and composition. For catalytic pur-poses, the alloy should have a high active surface area with