Ultrasound-assisted Micro-emulsion Synthesis of a Highly Active Nano- particle Catalyst

摘要

Several wet chemical methods were examined for synthesis of platinum (Pt) and Pt-cobalt (Co) nano-particles, including normal chemical synthesis, micro-emulsion synthesis, and ultrasound-assisted micro-emulsion synthesis. High resolution transmission electron microscopy (TEM), x-ray diffraction analysis (XRD), and electrochemical methods were used for characterization of the synthesized catalysts. The Pt-Co synthesized with ultrasound-assisted micro- emulsion showed uniform particle size distribution. The particle size was well controlled from 17 to 3 nm by varying the water/oil ratio, the water/surfactant ratio, the reactant concentration, and the pH value in the water phase. Several electrochemical methods were used to characterize the catalytic activity for oxygen reduction. The Pt-Co nano-particles synthesized with ultrasound-assisted micro-emulsion showed significantly higher catalytic activity for oxygen reduction than those synthesized with other wet chemical methods. It was able to catalyze oxygen 4-electron reduction to water at an onset potential about 0.65 V (vs. saturated calomel electrode SCE).