June 20, 2011 20:22 S1793-6047 00188 1 Functional Materials Letters Vol. 4, No. 2 (2011) 1–4 © World Scientific Publishing Company DOI: 10.1142/S1793604711001889 ELECTROCHEMICAL ACTIVITY OF COMPOSITE MATERIAL POLY(3,4-ETHYLENEDIOXYTHIOPHENE) MODIFIED BY SILVER HEXACYANOFERRATE ANDRZEJ P. NOWAK and ANNA LISOWSKA-OLEKSIAK ∗ Chemical Faculty, Department of Chemical Technology Gdansk University of Technology Narutowicza 11/12, 80-233 Gdansk, Poland ∗ alo@pg.gda.pl Received 30 December 2010; Revised 21 May 2011 An electrochemical way to prepare poly(3,4-ethylenedioxythiophene) (pEDOT) modified by silver hexacyanoferrate (Aghcf) is presented. The electrode material is synthesized in two-stage procedure. The first stage is galvanic silver electrodeposition on a glassy carbon substrate electrode. The second step is silver stripping followed by Aghcf formation during monomer oxi- dation. Deposited composite layer is compact but not homogenous in a micro-scale. The low spin iron centre redox activity depends on a kind of the electrolyte. Potassium and nitrate ions are the most suitable for redox couple reversibility. The redox activity diminishes in contact with electrolytes in series KNO 3 > K 2 SO 4 > KBr. In the presence of chloride ions redox activity of silver hexacyanoferrate is inhibited. Spectroelectrochemical measurements proved electrochromic character of the film. Keywords: Poly(3,4-ethylenedioxythiophene); silver hexacyanoferrate; cyclic voltammetry; spectroelectrochemistry. The electrode system consisted of conjugated conducting polymer and transition metal hexacyanoferrates is commonly known. 1, 2 Such systems may be used in different areas of application like electrocatalysis, 3 sensors, 4, 5 electrochromic devices, 6, 7 energy storage and conversion devices. 8–10 Among conducting polymers, the most popular is poly(3,4-ethylenedioxythiophene) (pEDOT) due to its chem- ical and thermal stability, low monomer oxidation potential and high conductivity. The transition metal hexacyanofer- rates (Mehcf) are used because of their redox couple activity, zeolitic structure and low costs. Organic–inorganic composites are attractive because of their potential to combine the electric capacity of both compo- nents under the condition that redox process of the inorganic network redox process lies in the potential range where the polymer is conductive. 11– 13 Modification of the electrodes consisted of conducting polymer and metal hexacyanoferrates can be achieved in many ways: (i) formation of multilayers electrodes, (ii) direct syn- thesis of inorganic compound inside polymer medium matrix or (iii) via electrodeposition from suspension. Here we show synthesis and characterization of the elec- trode material consisted of poly(3,4-ethylenedioxythiophene) and silver hexacyanoferrate based on electrodeposition. Electrochemical experiments were carried out using the potentiostat–galvanostat system AutoLab PGStat10 and Scan- ning Potentiostat EG&G, Model 362. A three-electrode one- compartment cell was used in all experiments. A platinum (Pt) (0.002 cm 2 ) or glassy carbon (GC) discs (0.03 cm 2 ) served as a working electrode. The working electrodes were pol- ished on alumina slurry (Buhler 0.05 µm) and rinsed thor- oughly using an ultrasonic bath. Platinum mesh was used as a counter electrode and Ag/AgCl/0.1 M KCl aq served as a reference electrode. In situ spectroelectrochemical measurements were performed in the quartz-deaerated cell with 0.1 M KNO 3 according to procedure given in the previous work. 14 A decon- volution of the UV-Vis spectra was performed by program GRAMS/32 (Galactic Industries Corporation, Salem, USA). Monomer 3,4-ethylenedioxythiophene (EDOT) from Bayer Co was used as received. Salts K 4 Fe(CN) 6 ,K 3 Fe(CN) 6 (Sigma-Aldrich), KNO 3 (EUROCHEM BGD Tarnów), AgNO 3 , KCl, K 2 SO 4 , KBr, NaNO 3 , NH 4 NO 3 (POCH Gliwice) were of analytical grade and used as received. Electrode material consisted of poly(3,4-ethylene- dioxythiophene and silver hexacyanoferrate (Aghcf) was obtained in two stages procedure. In the first stage silver was electrodeposited on the Pt substrate electrode under 1