The role of ion bridging in controlling competitive electrodeposition processes

Abstract

It was shown by the following three different types of measurements that the effect of thiocyanate on electrodeposition processes involving cobalt, nickel and lead could be predicted by regarding the thiocyanate as a bridging anion for deposition the transition elements and merely as a blocking agent for the deposition of the non-transition elements. 1. (1) Voltammetric methods showed that the thiocyanate increased the rate of deposition of the transition elements, cobalt and nickel, but only inhibited the deposition of the non-transition elements lead and hydrogen. 2. (2) Current efficiency measurements showed that addition of thiocyanate ions increased the current efficiency for the deposition of the transition elements cobalt and nickel, but decreased the current efficiency for deposition of the non-transition element lead. 3. (3) Alloy deposition studies showed that addition of thiocyanate ions increased the percentage of cobalt and nickel in cobalt-lead and Ni-Pb alloys.