Artículos de revistas
Controlled Size Nano-Polypyrrole Synthetized in MicroEmulsions as Pt Support for the Ethanol Electro-Oxidation Reaction
Autor
LUIS CARLOS ORDOÑEZ LOPEZ
Institución
Resumen
Polypyrrole (PPy) nanoparticles were synthesized by chemical polymerization in a microemulsion
system based on water, n–pentanol and sodium dodecyl sulfate (SDS) as surfactant, using pyrrole
monomer and ferric chloride (FeCl3) as oxidizing agent. Additionally, PPy-fibers were obtained by
adding n–decane to the polymerization system. PPy structures were characterized by scanning electron
microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) analysis demonstrated that
polymerization in microemulsion prevented the formation of a carbonyl function associated with
overoxidation of polymer chains. The presence of dodecylsulfate as doping agent was confirmed by
the S=O asymmetric stretching band in PPy-nanoparticles and PPy-fibers, while sulfur concentration
determined by energy-dispersive X-ray spectroscopy (EDX) can be related to the PPy doping level.
The PPy-nanoparticles conductivity was higher than that of other PPy tested materials tested. This is
attributed to the doping agent nature and the structure of the polymer chains. Electrocatalysts of Pt
supported on the PPy structures were obtained by reduction of H2PtCl6 by means of a NaBH4 solution.
Electrochemical measurements were performed in a three-electrode cell. Cyclic voltammetry results
from these Pt/PPy catalysts, showed the characteristic peaks of ethanol electro-oxidation. Pt/PPynanoparticles
presented lower charge transfer resistance (Rct) than a Pt/C catalyst. Ethanol electrooxidation
on Pt was enhanced by using nanostructured PPy as support. The PPy-nanoparticles showed
better structural, conducting and electrochemical activity properties than other PPy synthesized
materials tested as catalyst supports.