In situ STM and STS study of NixAl1−x alloy formation on Au(1 1 1) by electrodeposition from a molten salt electrolyte

The electrodeposition of Ni, NixAl1−x alloys and Al from the Lewis acid room temperature molten salt electrolyte AlCl3/1-methyl-3-butylimidazolium chloride on Au(1 1 1) has been studied by STM and voltage tunneling spectroscopy. Layer by layer growth of Ni starts already in the underpotential range, while below the equilibrium potential a columnar growth of 3D Ni clusters along 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 codeposition. The tunnel barriers φ, which were determined at the electrode/electrolyte interface, exhibit qualitatively the same relative reduction as for the vacuum interface.