The role of NH 4 + cations on the electrochemistry of Prussian Blue studied by electrochemical, mass, and color impedance spectroscopy

Abstract

The role of the ammonium cation on the reversible electrochemistry of Prussian Blue thin films was analyzed through in situ combination of three different impedance techniques. Electrochemical impedance spectroscopy provides information on the electron transfer. Mass impedance spectroscopy allows the exchange of free water, ammonium, and proton ions to be elucidated. Color impedance spectroscopy provides the kinetics of electrochromic changes of Prussian Blue structure (main backbone structure, ferrocyanide vacancies, and trapped structures). The simultaneous measurement of the three impedances gives detailed information on the mechanism of the whole process, specifically one faster and two slower, which have been identified during the electrochemical reactions of Prussian Blue films in NH 4 Cl acidic solutions.