The effect of plasma pre-treatment of carbon used as a Pt catalyst support for methanol electrooxidation

Abstract

Vulcan XC-72 carbon black for use as a catalyst support was treated in three different plasma atmospheres, H 2, Ar and O 2. The results showed that the microstructure and surface functional groups were significantly changed after plasma treatment. Pt/C catalysts were prepared by chemical reduction of H 2PtCl 6 with HCHO and those with untreated and plasma treated carbon black supports were characterized and tested for methanol electrooxidation. TEM showed that the platinum nanoparticles on H 2 and Ar plasma treated carbon were uniform and well distributed. Those on untreated carbon were uniform in most regions but coalesced in others. On O 2 plasma treated carbon agglomeration of the platinum nanoparticles was significant. XRD showed that the catalysts were composed of face-centered cubic Pt nanoparticles and XPS showed that they were metallic with no oxides present. Cyclic voltammetry and chronoamperometry were used to study methanol electrooxidation on the Pt/C catalysts in a solution of 0.5 M H 2SO 4 + 0.5 M CH 3OH, and showed that the catalytic activity those using H 2 and Ar plasma treated carbon was higher than for the untreated one. Catalysts supported by O 2 plasma treated carbon showed no catalytic activity. The treatment atmosphere of carbon therefore had a large effect on the catalyst performance, with the H 2 plasma being the best.