Ordered mesoporous carbons with controlled particle sizes as catalyst supports for direct methanol fuel cell cathodes

Abstract

The ordered mesoporous carbons (OMCs) with various primary particle sizes were synthesized and the effect of the particle size of the OMC supports on their performance for the oxygen reduction reaction (ORR) in direct methanol fuel cells was investigated. The ordered mesoporous silica (OMS) templates with particle sizes of 100, 300, and 700 nm (OMS-100, -300, and -700) were synthesized by changing the synthesis pH and Na content in the silica source, sodium silicate. The OMCs with similar particle sizes and morphologies (OMC-100, -300, and -700) were faithfully replicated by using the corresponding OMSs as templates and phenanthrene as a carbon source. Structural characterizations revealed that three OMCs exhibit uniform mesopores of 4-5 nm and BET surface areas of 600-800 m(2) g(-1). The Pt nanoparticles of ca. 3 nm were supported onto these OMCs and the resulting Pt/OMC catalysts were tested for the ORR. The three OMC supported catalysts exhibited the catalyst utilization efficiencies and ORR activities of similar range, with the values of Pt/OMC-300 catalyst being slightly higher than the other two catalysts.