Galvanodynamic study of the electrochemical switching effect in perfluorinated cation-exchange membranes modified by ethylenediamine

Perfluorinated sulfonyl-fluoride cation-exchange flat-sheet membranes were treated with ethylene diamine to investigate the influence of EDA-surface-t reatment on the process of electrochemical "switching" in such membranes. T he galvanodynamic method was used to obtain i-V cyclic curves of the membra nes. Electroless chemical deposition of Pt particles on modified membranes was achieved using the Takenaka-Torikai method. Galvanodynamic i-V cyclic c urves of the plain and platinum-containing aminated membranes were compared . Chemical modification of the membrane surface and membrane structure was investigated by means of electrical conductivity measurements and IR-spectr oscopy. Experimental results indicated that the "switching" phenomenon is m ore likely to occur due to a pH change in the electrolyte resulting in the formation of additional fixed-charged groups in the aminated layers of the membranes rather than due to heterolytic dissociation of water according to the second Wien effect. (C) 2001 Elsevier Science B.V. All rights reserved .