Effects of the coordination sphere in zinc deposition from NH4Cl solutions Conference Paper uri icon

abstract

  • The effect of the coordination sphere in the zinc deposition from different bulk complexes has been analyzed through electrochemical studies in chloride ammonium - ammonia baths. In acid zone, hydrogen evolution reaction (HER) was found to be coupled with the main reduction of zinc chloro-complexes. Neutral region of pH is characterized by a reduction mechanism merging of the coexisting chloro-amino-complexes, whereas in alkaline pH values, amino-complexes are the main pathway for depositing metallic zinc. The main role of chlorides is acting as inhibitors adsorbed to the substrate, and not bonded to the complex. This last fact is given by the promptly substitution of chlorides by ammonia ions in the zinc complexes, which may offer higher resistance to the charge tunneling, as well as detaching from the complex atmosphere. The reduction process in alkaline zone is additionally settled on the interaction between hydroxyl ions and ammonia. ©The Electrochemical Society.

publication date

  • 2008-01-01