L. Nyholm et Lm. Peter, WIDE PH RANGE MICROELECTRODE STUDY OF THE ELECTROCHEMICAL-BEHAVIOR OFPOLYANILINE FILMS IN BUFFERED SOLUTIONS, Journal of the Chemical Society. Faraday transactions, 90(1), 1994, pp. 149-154
Citations number
37
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
The electrochemistry of polyaniline (PANI) films deposited on platinum
microelectrodes has been studied in a wide pH region, at constant ion
ic strength. Cyclic voltammograms, recorded at a sweep rate of 100 V s
(-1) indicate that the films remain electroactive at pH values as high
as 9 provided that the films are only switched between their leucoeme
raldine and emeraldine states. This and the dependence of the electroa
ctivity on the cathodic limit employed in the experiments, suggest tha
t the loss of electroactivity often reported for pH values above 3-4 i
s unlikely to be caused by a deprotonation of the emeraldine salt. The
effect is more likely due to slow reduction of the fully oxidised PAN
I (pernigraniline). Experiments with films of different thicknesses in
dicate that PANI films are not in pH equilibrium with the bulk solutio
n and that the pH within the pores is lowered upon oxidation, probably
as a result of the concurrent expulsion of protons from the film. The
pH change within the pores is shown to depend on the buffer capacity
of the solution.