Polyoxometallates as inorganic templates for monolayers and multilayers of ultrathin polyaniline

The ability of a polyoxometallate (dodecamolybdophosphate) to form negatively charged monolayers on solid electrode surfaces is explored here to perform immobilization of monomeric (anilinium) units followed by electropolymerization within the monolayer. Consequently, hybrid films containing ultrathin conducting polymer (polyaniline) layers can be formed. By repeated and alternate treatments in solutions of dodecamolybdophosphate anions and anilinium cations, the amount of the material can be increased systematically in a controlled fashion leading to stable three-dimensional multilayer hybrid assemblies. The fact, that formal potentials of the dodecamolybdophosphate, redox processes appear in the potential range where polyaniline is conductive, allows the system to operate reversibly and reproducibly in acid electrolyte. (C) 2002 Elsevier Science B.V. All rights reserved.