A new approach for the synthesis of K-free nickel hexacyanoferrate

A Ni, Al hydrotalcite-like compound (Htlc) has been proven an useful host material for an alternative synthesis of a K⁺-free mixed hexacyanoferrate Ni_1.5Fe^III(CN)₆, which is very difficult to obtain in bulk. The first stage of the procedure consists in the intercalation of hexacyanoferrate(III) inside the Htlc structure. The intercalated Htlc has been treated with a NiNO₃ solution. The obtained material has been characterized by XRD, XAS Raman and FT-IR spectroscopy. The voltammetric response of the compound obtained after the complete solubilization of the Htlc host shows a typical fingerprint of nickel hexacyanoferrate material with a very low level of potassium. Elemental analysis confirmed the absence of K⁺ and thus the occurrence of K⁺-free nickel hexacyanoferrate (14% yield).