The work presented in this thesis addressed the synthesis of new type of porous carbon materials: ordered mesoporous carbons, and their applications as supports for catalytic nanoparticles.
Ordered mesoporous carbons have been synthesized via the template-directed synthesis strategy using ordered mesoporous silicas as templates. The synthesis procedure involves the infiltration of pores of mesoporous silicas with carbon precursors, such as sucrose, furfuryl alcohol and acetylene gas, their carbonization, and subsequent template removal by NaOH or HF. Mesoporous silica materials constructured with three-dimensionally interconnected pores, including MCM-48, SBA-1 and SBA-15 were successfully used to synthesize mesoporous carbons with cubic or hexagonal framework structures. The stabilities of the ordered mesoporous carbons have been evaluated by the X-ray diffraction patterns. The results indicated that the mesoporous carbons maintained their structural order under mechanical pressing and strong acid and base.
A general strategy for the synthesis of tube-type mesoporous carbon structures has been developed. The new carbon material, designated as CMK-5, was synthesized using mesoporous SBA-15 aluminosilicate as a template and furfuryl alcohol as a carbon source. The structural characterizations by X-ray diffraction, transmission electron microscopy and pore size analysis revealed that the CMK-5 carbon is constructed with the 2-dimensional hexagonal arrays of uniform carbon nanopipes. The CMK-5 mesoporous carbon contains two different mesopores: one pore is generated from the inside of carbon nanopipes and the other from the space between the adjacent nanopipes. The CMK-5 carbon exhibited very high surface area around $2000 ㎡g^{-1}$ and pore volume of $2 ㎤g^{-1}$.
The ordered mesoporous carbons as new supports for catalytic nanoparticles have been investigated. The nanopipe-type CMK-5 mesoporous carbon showed high metal dispersion upon supporting platinum nanoparticles, compared to common microporous carbons such as carbon blacks, charcoals and activated carbon fibers. The Pt cluster size can be controlled to mostly below 3 nm in diameter even as the Pt loading was increased to the same weight as the carbon support by a simple impregnation method using hexachloroplatinic acid. The Pt/CMK-5 catalysts exhibited excellent electrocatalytic activity for oxygen reduction.
A series of PtRu bimetallic nanoparticles with different compositions have been prepared onto CMK-5 mesoporous carbon by co-impregnation of metal precursors. The characterizations of PtRu/CMK-5 samples by $^{129}Xe$ NMR and EXAFS, in combination with XRD, TEM and hydrogen chemisorption indicated the formation of homogeneous bimetallic nanoparticles with an average particle size of 2-3 nm. The PtRu/CMK-5 showed composition-dependent catalytic activity toward methanol oxidation reaction.
