QUARTZ-CRYSTAL MICROBALANCE STUDY OF THE GROWTH OF INDIUM HEXACYANOFERRATE FILMS DURING ELECTRODEPOSITION AND COAGULATION

An electrochemical quartz crystal microbalance and cyclic voltammetry have been used to monitor fabrication of indium(III) hexacyanoferrate( III,II) films by electrodeposition through potential cycling and by in terfacial coagulation during ageing in the modification solution conta ining potassium electrolyte, indium(III) and hexacyanoferrate(III). We have chosen indium hexacyanoferrate as a model system since its cycli c voltammetry shows a single set of reversible, well-defined peaks sig nificantly separated from the solution responses. Simultaneous estimat ions of charge and mass have been used to characterize the efficiency of the deposition processes. Microgravimetry is particularly attractiv e for monitoring the film growth due to interfacial coagulation (at op en circuit). Electrodeposition by potential cycling permits fast prepa ration of thin films. The coagulation method is useful for fabrication of thick films. We also discuss the response of the resulting indium hexacyanoferrate film in the supporting electrolyte. The data are cons istent with the insertion and exclusion of K+ countercations during th e system's reduction and oxidation respectively.