Structural Alteration of Nanostructure Carbon Particles Carrying Pt Clusters in H₂ and O₂ Gases

Abstract

The effects of H2 and O2 gases on the typical fuel cell catalyst of Pt clusters on carbon particles (Pt on C) were examined using a special side-entry sample holder for high-resolution transmission electron microscopy. The holder can be used to transfer the specimen without exposure to air. The effects of H2 and O2 were detected after the specimen was exposed to the gases at 60 °C for 15 h. The predominant effect of H2 was the coagulation of the Pt clusters. The effect of O2 was to alter the structure of the carbon particles by oxidation.

Structural Alterations of Carbon Particles in Saturated Water Vapor

“…The alteration of the amorphous structure of the stable ribbon shape began at the surface, just as in the previous study. 3) This result shows that the oxidation energy of carbon particles induced the structural change in the carbon particles. These effects are barely seen in carbon films at this temperature.…”

“…2(c), as well as the effect of oxygen gas. 3) Figure 5 shows the results of altering the Ritsumei catalyst, in which Pt clusters were embedded in amorphous carbon particles as indicated schematically in Fig. 1(b).…”

“…It had been assumed that carbon particles on the order of 60 nm in diameter, as well as carbon film, were hardly altered in air by heating at 80 C because carbon is an attractive support in that it possesses satisfactory electrical conductivity and is obtainable in many different high surface area forms. 2) Previously, the effects of hydrogen gas and oxygen gas on the Pt particles on a carbon particle surface (Pt on C) were clearly observed at 60 C. 3) The impact of H 2 molecules on Pt clusters accelerated the movement of Pt clusters on the carbon surface causing the coagulation of Pt clusters. On the other hand, the graphitic structure (Vulcan carbon) surface changed to the amorphous structure in O 2 gas.…”