SPECTROSCOPIC INVESTIGATION OF A POLYPYRROLE MOS42-/MOS3 COMPOSITE FILM ELECTRODE IN AQUEOUS KCL SOLUTION/

Polypyrrole-tetrathiomolybdate-molybdenum trisulfide, PPy-MoS42--MoS3, thin film coated tin oxide electrodes have been studied by W-visible spectroscopy. The films are obtained by electrochemical polymerization from an aqueous solution of 0.5M pyrrole and 0.5 mM (NH4)(2)MoS4 at a potential of 0.7 V vs. SCE. The UV-visible spectroscopy data suggest that both tetrathiomolybdate anions and molybdenum trisulfide are rele ased from the film during the initial reduction sweep. potential cycli ng also induces a modification of the polymer structure involving loss of long-range order which is evidenced by a decrease of absorbance. A nalysis of the absorbance data at 380 and 720 nm according to Nernst l aw enabled the determination of the redox potentials which were found to be equal to -0.26 and 0.07 V,respectively. The former is related to polaron generation in the bandgap while the latter can be attributed to bipolaron production in the bandgap.