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RESEARCH PRODUCT

Insights on the Mechanism of Insoluble-to-Soluble Prussian Blue Transformation

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description

The electrochemical transformation of the soluble form of Prussian blue (PB) material from the insoluble form was monitored using electrochemical, gravimetric, acoustic, and spectroscopic techniques simultaneously. The described combination of in situ techniques represents an innovative tool for measurement in electrochemistry, which provides complementary information on the electrochemical systems. The insoluble-to-soluble PB transformation process takes place during the successive voltammetric cycles between the mixed valence form (PB) and the fully reduced form [Everitt's salt (ES)]. One of the processes that takes place is the exit of free Fe(CN) 4- 6 ions occluded in the vacancies of the insoluble PB crystalline framework during the fresh PB electrodeposit process. In potassium salt solutions, the exit of each ferrocyanide ion is compensated by the entrance of two potassium ions and six hydroxyl anions. This species exchange increases the manifestation of viscoelastic phenomena of the rigid skeleton from the insoluble PB form to the soluble one, which could facilitate the appearance of an internal magnetic field at room temperature during the soluble PB ⇄ ES voltammetric cycle.