Nanocomposite films containing Au nanoparticles formed by electrochemical reduction of metal ions in the multilayer films as electrocatalyst for dioxygen reduction

Through electrostatic layer-by-layer assembly, AuCl4(-) anions and [tetrakis(N-methylpyridyl)porphyrinato] cobalt (CoTMPyP) cations were alternately deposited on indium tin oxide (ITO) substrates, and 4-aminobenzoic acid modified glassy carbon electrode. Electrochemical reduction of AuCl4(-) anions sandwiched between CoTMPyP layers leads to the in situ formation of Au nanoparticles in the multilayer films. Regular growth of the multilayer films is monitored by UV-vis spectroscopy. UV-vis spectroscopy, X-ray photoelectron spectroscopy and cyclic voltammetry confirm the formation of Au nanoparticles in the multilayer films after electrochemical reduction of AuCl4(-) anions. Atomic force spectroscopy verifies that the as-prepared Au nanoparticles are uniformly distributed with average particles diameters of 20-25 mu. The resulting composite films containing Au nanoparticles with high stability exhibit high electrocatalytic activity for the reduction of dioxygen. Rotating disk electrode voltammetry and rotating ring-disk electrode voltammetry demonstrate the Au nanoparticles-containing films can catalyze two-electron reduction of O-2 to H2O2 in O-2-saturated 0.1 M H2SO4 solution. (c) 2004 Elsevier B.V. All rights reserved.