Preparation and Characterization of Composite Films of Polypyrrole with Metal Oxide /Hydroxides Using Galvanic Corrosion Reaction

Abstract

The interactions of electropolymerized polypyrrole ͑PPy͒ films with evaporated aluminum and indium layers were investigated. The apparent occlusion of the metals into the PPy films was induced simply by their storage in air, giving rise to PPy-metal oxide/hydroxides composite films. More important, the composites showed stability against the electrochemical redox cyclings and metal-dependent electric conductivity. The formation of the composite materials was explained by assuming the corrosion reaction that proceeds in the galvanic cells formed between the PPy films and the metals. This assumption was experimentally supported by various control and simulation experiments.Metal ͑or inorganic semiconductor͒/conjugated polymer interfaces have been attracting considerable attention in recent years, and much effort has been made in the understanding of their unique electronic and chemical properties. 1,2 This is because the knowledge of such interfaces should aid and promote the application of polymers in junction devices such as diodes, 3-5 solar cells, 6-8 and electroluminescent devices, 9 as well as their application to corrosion protection. 10,11 The interactions at the interfaces produce various electronic states ͑or chemical bonds͒ depending on the combination of polymers and metals ͑or inorganic semiconductor͒, and accordingly, contribute to the performances of such electronic devices. [12][13][14] We now report our finding that the strong interactions between the evaporated metals ͑Al or In͒ and a conducting polymer ͑poly-pyrrole͒ film cause the former to be apparently occluded into the latter matrix film, and that the resulting organic/inorganic hybrid materials are characterized by their enhanced stability to oxidationreduction ͑or doping-dedoping͒ cycles and their metal-dependent electric conductivity. ExperimentalPolypyrrole ͑PPy͒ films were prepared on an indium-tin oxide coated glass ͑ITO͒ plate by the controlled-potential electropolymerization of pyrrole 15,16 at 1.1 V vs. a saturated calomel electrode ͑SCE͒ in a CH 2 Cl 2 solution containing 65 mM of tetraethylammonium perchlorate ͑TEAP͒ at 0°C under an N 2 atmosphere, followed by washing with CH 2 Cl 2 , air drying at room temperature, and vacuum evaporation of the metals. The film thickness was changed by varying the amount of electricity passed during the electropolymerization and determined by a scanning electron microscopic analysis. For the X-ray photoelectron spectroscopic ͑XPS͒ measurements, a ULVAC phi ESCA 5400 spectrometer with Mg K␣ radiation was used. The absolute binding energy scale was obtained by setting the C 1s peak to 284.6 eV. The composition depth profiles of the films were measured by the combination of argon ion sputtering with XPS. The film conductivity measurements were carried out using the four-point-probe technique. For the measurements of the conductivities, the PPy films were peeled off the ITO electrode and mounted on an insulating adhesive tape. The amount of ClO 4Ϫ incorporated into the as-grown PPy film, i.e., doping ...

Surface‐enhanced Raman scattering study of Ag@PPy nanoparticles

“…In recent years, much effort has been devoted to the investigation of the conducting polymer deposited on metal substrates, and their enhanced vibrational spectra have been obtained by using surface‐enhanced vibrational spectroscopy (SEVS), including surface‐enhanced Raman scattering (SERS) and surface‐enhanced infrared absorption (SEIRA) 8, 9. In particular, the effect of doping on optical and electronic properties of conducting polymers has been reported 10–13…”

Polycarbazole Nanocomposites with Conducting Metal Oxides for Transparent Electrode Applications

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