Cyclic voltammetric studies of Prussian blue and viologens within a paper matrix for electrochromic printing applications

The apparent redox response of Prussian blue (PB, iron(III) hexacyanoferrat e(II)) within a paper matrix is similar to that found in conventional liqui d electrolyte voltammetry using a PB-modified electrode; however part of th e response is from PB which adsorbs onto the glassy carbon (GC) working ele ctrode. Application of a Nafion(R) coating to the PB-impregnated paper matr ix prevents transfer of PB to the GC surface. In contrast to the PB system, the redox response of the 1,1'-dimethyl-4,4'-bipyridilium (MV, methyl viol ogen) system, where both redox states examined are soluble, is confined who lly to the paper matrix. For the case of 1,1'-diheptyl-4,4'-bipyridilium (H V, heptyl viologen), the electrogenerated insoluble radical cation salt ads orbs onto the GC electrode, the KCl-impregnated paper acting simply as the electrolyte medium. PB can be electrogenerated within a paper matrix, with the possible application in monochrome electrochromic printing systems. (C) 1999 Elsevier Science S.A. All rights reserved.