Underpotential Deposition of Aluminum and Alloy Formation on Polycrystalline Gold Electrodes from AlCl[sub 3]/EMIC Room-Temperature Molten Salts

Interfacial processes occurring at polycrystalline gold in acidic 1‐ethyl‐3‐methylimidazolium chloroaluminate melts at room temperature, at potentials more positive than aluminum bulk deposition, include both Al underpotential deposition and the formation of Al/Au alloys. This information complements that reported in the literature for Al electrodeposition on Au in melts at temperatures of 200°C and higher. Cyclic voltammetry and chronopotentiometry suggest that at least two alloys form, and there is fast phase transformation between these intermetallic compounds at room temperature in the aluminum underpotential region. This transformation with thin gold films was slower than that in bulk gold electrodes.