THE ANALYSIS OF THE ZINC AND IRON GROUP METAL ALLOY CODEPOSITION MECHANISM USING AN EQCM

摘要

The anomalous codeposition of Zri-Ni may be due to the preferential precipitation of zinc hydroxide on the cathode and the inhibition of nickel deposition according to the hydrogen production at the cathode and the pH increase. However, we report here that when both Zn~(2+) and Ni~(2+) coexist in the solution, the zinc hydroxide does not precipitate while the double hydroxide of both metals does. In this paper, the formation of the double hydroxide and its electrolytic reduction at the cathode in zinc-nickel alloy deposition were investigated. By using an EQCM method combined with electrochemical measurements, it was clarified that hydrogen generation occurs prior to the alloy deposition and the double hydroxide adheres to the electrode surface. The double hydroxide adsorbed on the cathode surface probably acts as a precursor of the alloy deposition reaction.