In situ STM and STS study of NixAl1-x alloy formation on Au(111) by electrodeposition from a molten salt electrolyte

The electrodeposition of Ni, Ni,AII, alloys and Al from the Lewis acid room temperature molten salt electrolyte AlCl3/1-methyl-3-butylimidazolium chlo ride on Au(111) has been studied by STM and voltage tunneling spectroscopy. Layer by layer growth of Ni starts already in the underpotential range, wh ile below the equilibrium potential a columnar growth of 3D Ni clusters alo ng the step edges is observed. At potentials below -0.2 V vs Ni/Ni(II) the complete Au surface is covered with a 3D deposit due to Ni and Al codeposit ion. The tunnel barriers phi. which were determined at the electrode/electr olyte interface, exhibit qualitatively the same relative reduction as for t he vacuum interface. (C) 2001 Elsevier Science B.V. All rights reserved.