Abstract

We have prepared ultrathin, nanostructured melanin films on Au(111) by means of electrochemical self-assembly. These films were characterized by using Auger electron spectroscopy, X-ray absorption near-edge structure spectroscopy. scanning tunneling microscopy, magnetic force microscopy, and electrochemical techniques. Two types of nanostructures are present in the film: melanin nanoparticles and Fe3O4 nanoparticles. The melanin nanoparticles contain Fe bonded to oxygen-containing phenolic groups in an octahedral configuration similar to that found in Fe2O3. The inorganicorganic composite exhibits magnetic properties and catalyzes the electroreduction of hydrogen peroxide in alka-line and neutral electrolyte solutions. The electrocatalytic activity depends on the Fe-bound melanin and appears to be similar to that found for Fe-porphyrins. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.