Thermal oxygen activation followed by in situ work function measurements over carbon-supported noble metal-based catalysts

Abstract

In this work, polycrystalline platinum-based nanoparticles were deposited onto two different carbon supports: carbon black and multiwalled carbon nanotubes. The samples were characterized by Raman spectroscopy, transmission electron microscopy and tested using a Kelvin probe to measure the work function changes upon oxygen adsorption at different temperatures. The same materials were evaluated as electrocatalysts for the oxygen reduction reactivity under acid conditions, in a three-electrode configuration, in a rotating disc electrode setup. Since both Kelvin probe work function measurements and rotating disc electrode measurements provide the sample averaged surface properties, the correlation of results from these two techniques can be useful for the understanding of the catalysts' performance. A striking correlation between the electrocatalytic activity with the material's ability to activate molecular oxygen was observed. The obtained results were rationalized in terms of electronic interaction between the supporting carbon material, and a metallic component.