In situ SERS and ERS assessment of the effect of triethanolamine on zinc electrodeposition on a gold electrode

Abstract

The electrodeposition of zinc and its alloys have been widely studied for several technological reasons. The use of additives can improve the morphology and the physico-chemical properties of the coating. Understanding of the interaction of additives with the substrate during electrodeposition is important for control of the process. In this work, triethanolamine (TEA) as an additive for Zn electrodeposition in alkaline media was studied. The chemical and electrochemical characterization of the surface was carried out by in situ Surface Enhanced Raman Spectroscopy (SERS), in situ Electroreflectance Spectroscopy (ERS) and cyclic voltammetry. The morphology of the coating was analyzed by SEM. It was found that it is possible to follow the adsorption of organic molecules during Zn electrodeposition by SERS. Furthermore, the TEA actively participates during the electrodeposition process. TEA and its reaction products adsorb in a different manner on the electrode depending on the applied potential and the decrease in the kinetics of Zn reduction. The coatings obtained from electrolytes with TEA are uniform with refined grain size compared with the TEA-free electrolyte.