Nonanomalous Electrodeposition of zinc-iron alloys in an acidic zinc chloride-1-ethyl-3-methylimidazolium chloride ionic liquid

The electrodeposition of iron and Zn-Fe alloys on polycrystalline nickel was investigated in the 40.0-60.0 mol % zinc chloride-1-ethyl-3-methylimidazolium chloride ionic liquid containing iron(II) at 90degreesC. Iron(II) was electrochemically reduced to iron metal before the reduction of zinc(II) to zinc metal, and anomalous codeposition of Zn-Fe did not occur in this ionic liquid. Underpotential deposition of zinc on iron was observed prior to the electrodeposition of bulk zinc. Dimensionless chronoamperometric current/time transients for the underpotential deposition of zinc on iron were in good accord with the theoretical transients for the two-dimensional nucleation and/or growth of the nuclei. Zn-Fe alloys could be prepared in the potential range of the underpotential of zinc on iron or the potential range where bulk deposition of zinc occurred. Energy-dispersive spectroscopy data indicated that the composition of the Zn-Fe alloys was dependent upon the deposition potential and the iron(II) concentration in the plating solution. The morphologies of the Zn-Fe codeposits were examined by scanning electron microscopy. (C) 2003 The Electrochemical Society.