Formation and characterization of heteropolyacid/polycation multilayer films on gold electrode

Ultrathin multilayer films of a polybasic lanthanide heteropoly tungstate-m olybdate complex and a cationic polymer of quaternized poly(4-vinylpyridine ) partially complexed with osmium bis(2,2'-bipyridine) have been fabricated on a gold electrode precoated with a cysteamine self-assembled monolayer. The multilayer films have been characterized by optical spectroscopy, small -angle X-ray diffraction, and electrochemical methods (cyclic voltammetry a nd electrochemical impedance). Especially, the electrochemical impedance sp ectroscopy is developed to monitor the layer deposition processes. It provi des important information such as double-layer capacitance and charge-trans fer resistance. All obtained results reveal regular film growth with each l ayer adsorption. (C) 2001 The Electrochemical Society.