Network films of conducting polymer-linked polyoxometalate-modified gold nanoparticles: Preparation and electrochemical characterization

The ability of Keggin-type phosphododecamolybdate (PMo12O403−, PMo12) to undergo chemisorption on solid surfaces (including gold) is explored here to convert (by ligand place-exchange and phase transfer to aqueous solution) the alkanothiolate-modified Au nanoparticles of controlled size (prepared in toluene) into a stable colloidal solution of PMo12-protected gold nanoparticles, PMo12–AuNPs, the sizes of which are ca. 4–5 nm as determined by transmission electron microscopy. By dip-coating, PMo12–AuNPs were assembled on carbon electrode substrates. The step-by-step assembly, by which alternate exposures to the solutions of PMo12–AuNPs and either anilinium cations or pyrrole monomers, was utilized to grow in controlled manner hybrid network films in which the negatively charged PMo12–AuNP deposits were linked, or electrostatically attracted, by ultra-thin, positively charged conducting polymer (polyaniline or polypyrrole) structures. The three-dimensionally distributed PMo12–AuNPs immobilized within the polypyrrole-based composite film exhibited some electrocatalytic reactivity towards reduction of hydrogen peroxide.