Electrocatalytic and Magnetic Properties of Ultrathin Nanostructured Iron–Melanin Films on Au(111)

Abstract

We have prepared ultrathin, nanostructured melanin films on Au- ACHTUNGTRENUNG(111) by means of electrochemical selfassembly. 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 inorganic– organic composite exhibits magnetic properties and catalyzes the electroreduction of hydrogen peroxide in alkaline and neutral electrolyte solutions. The electrocatalytic activity depends on the Fe-bound melanin and appears to be similar to that found for Fe–porphyrins.