Hybrid Pt Nanostructures by Metallization of Organic Films

The synthesis of stable Pt nanoparticles (Pt NPs) and their attachment to glassy carbon (GC) and gold electrodes have been investigated. Two strategies have been followed, by reaction with the thiol termination of a self-assembled monolayer of 1,4-benzenedimethanethiol (BDMT) on gold and by chemical bonding through an amide linkage between the carboxylate group of 11-mercaptoundecanoic acid (MUA)-stabilized Pt NPs and aminophenyl groups grafted on a GC electrode. The functionalized substrates and the Pt NPs synthesized were characterized by reflectance adsorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy, ellipsometry, and high-resolution transmission electron microscopy (HRTEM). Their electrocatalytic properties for the oxygen reduction reaction (ORR) were investigated by rotating disk electrode measurements. It is shown that particles attached by amide bond formation from a C11 tether lead to a decrease in the ORR rate constant by a factor of approximately 5 compared with Pt NP connected to the electrode surface by phenyl group that provides a high conductivity between the substrate and the Pt particles. The ORR occurs through a four-electron transfer on both electrodes

An Approach to Fabrication of Metal Nanoring Arrays

Fabrication of tailored nanomaterials with desired structure and properties is the greatest challenge of modern nanotechnology. Herein, we describe a wet chemical method for the preparation of large area metal nanoring arrays. This method is based on self-assembly of polystyrene sphere template on a flat substrate and wicking/reducing metal precursor into the interstices between the template and the substrate. In this article, platinum, gold, and copper nanorings were fabricated by applying 505 nm polystyrene spheres onto highly oriented pyrolytic graphite (HOPG) and Si(100) substrates, followed by reducing the templated metal salt with NaBH4. AFM images reveal formation of arrays of metal nanorings comprising metal nanoparticles with the average ring height of 5.7 ± 0.8 nm and diameter of 167.3 ± 8.9 nm. XPS confirms that these structures are metallic

Substrate Structural Effects on the Synthesis and Electrochemical Properties of Platinum Nanoparticles on Highly Oriented Pyrolytic Graphite

Platinum nanoparticles have been prepared by potentiostatic multipulse electrodeposition with controlled nucleation and growth on freshly cleaved and electrochemically oxidized highly oriented pyrolytic graphite. The influence of the applied potential sequence on the size distribution was investigated. For short electrolysis times, the deposition of nanoparticles takes place via a progressive nucleation mechanism. A narrow size distribution was obtained by controlling independently the nucleation and growth steps, and particles with heights between 52 and 1.4 nm could be prepared by altering the pulse parameters. Anodic oxidation of the substrate had a large influence on the particle size, resulting in the preparation of particles 1.4 nm in height. XPS demonstrated that Pt particles of small size were readily oxidized. The rate of electrochemical methanol oxidation showed a dependence on the particle size, and no oxidation of methanol could be observed for the smaller sizes investigated