SPECTROELECTROCHEMICAL STUDIES OF INDIUM HEXACYANOFERRATE ELECTRODES PREPARED BY THE SACRIFICIAL ANODE METHOD

Indium hexacyanoferrate (InHCF) thin films have:been successfully depo sited on the SnO2-coated surface of conductive float glass by the sacr ificial anode (SA) method. It was found that InHCF films prepared in s uch a way possess relatively smooth surface morphology, presumably inf luenced by the anodic dissolution current. The films have been charact erized and discussed in terms of their electro-optical properties, The compositions of as-deposited InHCF films prepared by the SA method we re analyzed by atomic absorption (AA) spectroscopy and can actually be expressed as H1-x(KxInFe(CN)(6). mH(2)O, with 0 less than or equal to x less than or equal to 0.38. Cyclic voltammetry (CV) done in various electrolytes supports the double injection/extraction mechanism durin g switching. It is concluded that ion permeability:in an InHCF film fo llows the order of Na+ > K+ > NH4+ > Li+. A one-electron transfer reac tion is proposed for the switching of the InHCF film according to the absorption spectra. The film is shown to be electrochromic, and the re dox reaction can be summarized as MInFeII(CN)(6). mH(2)) reversible ar row InFeIII(CN)(6). mH(2)O + M+ + e(-) where M+ is the metal cation in supporting electrolytes. The coloration efficiency for the InHCF film switching involving K+, measured at 410 nm, is 47.6 cm(2)/C for color ing and is 47.3 cm(2)/C for bleaching, indicating nearly ideal electro chromic behaviors.