Preparation, characterization, and electrocatalytic oxidation properties of iron, cobalt, nickel, and indium hexacyanoferrate

Using consecutive cyclic voltammetry, iron(II), cobalt(II), nickel(II), and indium(III) hexacyanoferrate films have been prepared, and their electrocatalytic properties in electrolytes containing various cations have been determined. Cyclic voltammograms recorded the electrochemical formation of nickel(II) hexacyanoferrate films using 13 cations: Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, H+, NH4+, tetraethylammonium cation, and Al3+. The electrochemical formation of the iron(II), indium(III), and cobalt(II) hexacyanoferrate films from different cation solutions with the same concentration showed different cyclic voltammograms. The deposition growth of the cobalt(II) and nickel(II) hexacyanoferrates in aqueous Ca(NO3)2 and Ba(NO3)2 solutions immersed in various aqueous cation solutions were consistent with the EQCM and spectroscopic data. The electrocatalytic oxidation of SO32− and S2O32− by various metal hexacyanoferrate film catalysts in electrolytes of various cations showed some selectivity towards several cations and also showed varying redox potentials.