Electrochemical behavior of a series of undecatungstozincates monosubstituted by first-row transition metals, ZnW11M(H2O)O39n– (M = Cr, Mn, Fe, Co, Ni, Cu or Zn)

Abstract

The electrochemical behavior of a series of undecatungstozincates monosubstituted by first-row transition metals, ZnW₁₁M(H₂O)O₃₉^n– (M = Cr, Mn, Fe, Co, Ni, Cu or Zn), was investigated systematically and comparably in aqueous solutions by electrochemical and in situ UV-visible-near-IR spectroelectrochemical methods. These compounds exhibit not only successive reduction processes of the addenda atoms (W) in a negative potential range, but some of them also involve redox reactions originating from the substituted transition metals (M) such as the reduction of Fe^III and Cu^II at less negative potentials and the oxidation of Mn^II at a more positive potential. Some interesting results and phenomena, especially of the transition metals, were found for the first time. Moreover, possible reaction mechanisms are proposed based on the experimental results.