(200a) Carbon-embedded or -supported Pt Nanoparticles Made in Flames

Most platinum-based catalysts consist of nanometer-sized metal particles dispersed on high-surface-area supports. They find application as catalysts in many chemical processes, such as hydrogenation, oxidation, and reforming, but also in electrodes for fuel cells. Flame spray pyrolysis (FSP) has been used for the synthesis of carbon black-supported noble metal catalysts (1 to 10 wt% Pt). Liquid precursors containing specific amounts platinum precursor dissolved in xylene were dispersed by nitrogen and combusted in a closed flame chamber resulting in nanostructured powders. Depending on process conditions, the product results in Pt-nanoparticles supported on a carbon matrix or carbon coated Pt-nanoparticles. In both cases, platinum was well dispersed and confined to the carbon matrix. The as-prepared powders were collected on a filter and characterized by Raman spectroscopy, scanning transmission electron microscopy, CO chemisorption, nitrogen adsorption, X-ray diffraction, electrochemical dissociation of di-oxygen and hydrogenation of cyclohexene to confirm catalytic activity. The specific surface areas of the powders ranged from 70 to 300 m²/g depending on the oxygen and precursor flow rates.