Simultaneous formation of separate conducting and insulating layers on aluminum electrode by electrolysis

Two films, conducting (polypyrrole; PPy) and insulating (Al2O3), were succe ssfully formed as separate layers on an Al electrode by a simple electroche mical oxidation of aluminum metal in aqueous solution which contains pyrrol e monomer and an anionic surfactant electrolyte, namely, n-dodecylbenzenesu lfonate. Using a surfactant electrolyte, three layers of thin films (PPy/Al 2O3/Al) can be simultaneously formed simply by electrolyzing Al metal. The formation of PPy/Al2O3 layers on Al electrodes has been confirmed by direct observation (using scanning electron microscopy) and characterized electro chemically. AC impedance spectroscopic analysis demonstrated an excellent i mpedance-frequency characteristic for a sample electrolytic capacitor forme d from a PPy/Al2O3/Al film. (C) 1998 The Electrochemical Society, Inc. S109 9-0062(97)10-116-X.