Electrochemical in situ STM study of phase formation during Ag and Al electrodeposition on Au(111) from a room temperature molten salt

Abstract

The electrodeposition of Ag and Al on Ñame annealed Au(111) Ðlms from an acidic aluminium chlorideÈ1-methyl-3-butylimidazolium chloride room temperature molten salt has been investigated by electrochemical scanning tunneling microscopy, cyclic voltammetry and potential step experiments. The cyclic voltammogram of Ag on Au(111) is characterized by adsorption controlled Ag underpotential deposition (upd) and di †usion controlled Ag overpotential deposition (opd). Starting from the anodic limit, bulk oxidation of Au is observed to start near ]1.25 V vs. Ag/Ag`reference electrode (RE). In the upd range, two dimensional Ag islands form which merge in a coherent Ag monolayer near 0.05 V vs. RE. With further reduction of the potential, a second monolayer grows. The corresponding chronoamperometric measurements show exponential behaviour with time constants of the order 10 s~1 consistent with a Langmuir adsorption model. In the opd range, a di †usion controlled layer by layer growth of Ag clusters occurs, the bulk Ag`di †usion coefficient being (1.4 ^0.2) ] 10~6 cm2 s~1. Alloying of Ag with codeposited Al from the electrolyte has to be considered. For the Al electrodeposition on Au(111), strong indications for alloying have been observed starting at a potential of ]0.95 V vs. Al/Al3`RE. Below ]0.55 V, the formation of two dimensional Al islands is seen followed by a three dimensional growth whereby a strong tendency for alloying has to be considered.

A promising method for electrodeposition of aluminium on stainless steel in ionic liquid

“…It also makes it smaller that the overpotential required to drive the deposition process. However, the electrodeposition was usually performed on limited substrates such as platinum, 35,44 tungsten, 35,37,53 gold, 43,54 copper, 41,55 and glass carbon. 35 Electrodeposition of Al on stainless steel is hardly investigated and it would be very interesting and important to electrodeposit Al on stainless steel.…”

The Electrode/Ionic Liquid Interface: Electric Double Layer and Metal Electrodeposition

“…Both Cu [134] and Ag [156] form island UPD structures on Au(111) in the [BMI]Cl-AlCl 3 ionic liquid. On the Cu island, a moirØ pat- .…”

Al-Ag alloy formation by aluminium underpotential deposition from AlCl3+NaCl melts on silver substrate

“…As the name suggests, the method consists of codepositing at least two elements from the same solution. The same was found to be true for some alloys [32,44] and aluminium alloys from inorganic [12] and organic melts [12,[44][45][46].…”

“…This was also realized for aluminium UPD from inorganic [12,14,33,[38][39][40][41][42][43][44][45][46][47] and organic melts [12,37,48,49].…”