Electrodeposition of composite films consisting of polypyrrole and mesoporous silica

Electrochemical formation of composite films consisting of polypyrrole (PPy) and MCM particles has been presented, in which pyrrole is electrochemically oxidized in an aqueous solution with suspension of purely siliceous or aluminum-containing MCM-41. The composite films were characterized by scanning electron microscopy, X-ray diffraction and infrared reflection spectroscopy, and the electrochemical response of the PPy/MCM-deposited electrode to Fe(CN)63− investigated. From IR spectra, it is indicated that the polymerization of pyrrole takes place on the internal wall of MCM particles where the cationic PPy is charge-balanced by the negatively charged MCM. A PPy/SiMCM composite electrode prepared in the presence of higher concentration of pyrrole (≧0.5 M) shows a reproducible electrochemical response for Fe(CN)63−. The CV curve on this electrode is comparable to that on pure PPy-modified electrode, and it is suggested that the negative charge on the mesopore surface is almost completely neutralized by the positive charge of PPy.