Received: August 2, 2007

In Final Form: October 25, 2007

Abstract:

Self-assembling of Pt nanoparticles (nPts) on a sol-gel-derived 3-D silicate network and the electrocatalytic activity of nPts toward oxidation of methanol and reduction of oxygen is described. Colloidal nPts were self-assembled on the thiol functional group of the silicate network preassembled on a polycrystalline Au electrode. The nanostructured particles on the network have been characterized by Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, X-ray diffraction, and electrochemical measurements. The nPts on the silicate network have the size distribution between 7 and 10 nm and have a near-spherical shape. The nanosized Pt particles exhibit high electrocatalytic activity for the oxidation of methanol and reduction of oxygen when compared to bulk Pt electrode in terms of onset potential and current density. The onset potential for the reduction of oxygen is 300 mV less negative than that observed on bulk Pt electrode. The current density for the oxidation of methanol and reduction of oxygen with the nanostructured electrode is significantly higher than that on the bulk Pt and other nanomaterial-based electrodes. The nanoparticle coverage (_p) on the silicate network has control over the electrocatalytic activity of nPts. These highly dispersed nanosized Pt particles on the sol-gel network are very promising for fuel cell application.

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