Long-term stability of Cd(0001) single crystal | ionic liquid interface – The effect of I− addition

Abstract

• The interface between Cd(0001) and EMImBF 4 mixtures with EMImI was investigated. • Studied interface was unstable in long-scale time conditions. • The addition of I − contributed to the corrosion of the Cd(0001) surface. • Institute of Chemistry, University of Tartu, Ravila 14A, 50,411 Tartu, Estonia. In this study, the capacitive behaviour and stability of the interface between Cd(0001) electrode and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4 ) mixtures with 0 wt%, 5 wt%, or 10 wt% 1-ethyl-3-methylimidazolium iodide (EMImI) addition have been investigated by using electrochemical impedance spectroscopy, cyclic voltammetry, and scanning tunnelling microscopy. It is shown that the reversible adsorption of I − ion significantly increased the capacitance in comparison with EMImBF 4 . Concurrently, the addition of I − ion contributed to the corrosion of the Cd(0001) surface, which was shown by the increase of capacitance and surface roughness over 72 h after electrochemical polishing.