Electrochemical formation of ultra-thin Ag/Cd films onto Au(111) substrates

Abstract

The formation of an ultrathin bilayer of Ag/Cd in the system Au(111)/Ag+,Cd2+,SO2 2/4 has been studied by conventional electro-chemical techniques and in situ scanning tunneling microscopy (STM). Cyclic voltammetric measurements carried out in a solution con-taining both Ag+and Cd2+ions have shown that the deposition of Cd onto the Au(111) modified with 3.75 ML of Ag originatesadsorption/desorption UPD peaks which are similar to those obtained in the system Ag(111)/Cd2+. These results demonstrate thatthe Au(111) surface was completely screened by the Ag layers which were epitaxially oriented respect to the substrate. Therefore, anultrathin Ag(111) film was formed onto the Au(111) surface, on which a Cd ML was subsequently deposited by UPD, with the finalproduct of an ultrathin Ag–Cd bilayer on the gold substrate. The morphological surface changes during the Ag deposition and subse-quent Cd UPD on the modified substrate were followed by in situ STM imaging.