Electrodeposition of Copper on Pt(111) Pretreated with Organic Adsorbates

Abstract

Underpotential Deposition / Copper / Inhibition / Pyridine-Derivatives / Bis-Pyridine Derivatives / PyrazineThe deposition of copper on Pt(111) has been studied in the underpotential (UPD) and overpotential (OPD) regions using cyclic voltammetry in the presence of organic coadsorbates including pyridine, pyrazine, 2,2'-bipyridine, 4,4'-bipyridine, 4-phenylpyridine, 1,2-bis(4-pyridyl)ethane and 1,2-bis(4-pyridyl)ethylene dissolved in either 0.5 M H 2 SO 4 or water. Adsorbates bind primarily through a ring nitrogen atom, delaying both UPD and OPD processes according to the bond strength of the adsorbed layer. These adsorbates also show a significant pH dependence due to protonation of the binding nitrogen atom. Their behavior has been compared in neutral and acid media, taking into account packing density, molecular footprints, adsorbed layer thickness, ability to form complexes with copper ions, and adsorption strength.