Abstract

Nanoparticles, objects having sizes 1–1000 nm, have properties that are different from either single atoms or bulk material. Nanoparticles are found in many technological applications including fuel cells and medical diagnostic tools. This research aims to study the chemistry of nanoparticles in situ on a single particle basis. Single Pd and Pt nanoparticles (NPs) were studied by their ability to catalyze the oxidation of hydrazine in solution while isolated at the surface of an ultramicroelectrode (UME). The oxidation of hydrazine proceeds slower at the surface of the Au UME compared to Pd and Pt NPs which land on the electrode; this resulted in a jump in current anytime one NP landed at the Au UME surface and catalyzed the reaction. The Pd and Pt NPs were synthesized by reduction of their chloride salts in the presence of sodium citrate as the capping agent. The size of the Pd and Pt NPs was independently determined by transmission electron microscopy. This allowed correlation of the particle size to the jump in the current observed in the collisions. Preliminary experiments investigating the detection of Pd NPs using hydrogen peroxide oxidation and glucose oxidation will also be described. The overall goal of this research is to extend the method of electrocatalytic amplification to new materials and reactions, generating fundamental insights to catalysis at metal NPs.