Ordered uniform porous carbon frameworks showing interesting morphology variations were synthesized against removable colloidal silica crystalline templates through simply altering acid catalyst sites for acid-catalyzed polymerization. These highly ordered uniform porous carbons as a catalyst supporter resulted in much improved catalytic activity for methanol oxidation in a fuel cell.
Carbon capsules with hollow core/mesoporous shell (HCMS) structures have been synthesized (see Figure for schematic) for the first time using solid core/mesoporous shell (SCMS) silica spheres as templates. The capsules have bimodal pore systems consisting of a uniform, tunable, hollow macroscopic core and a mesoporous shell, thus leading to a great variety of possible applications.
Ordered uniform porous carbon frameworks with pore sizes in the range of 10 to ∼1000 nm were synthesized
against removable colloidal silica crystalline templates by carbonization of phenol and formaldehyde as a
carbon precursor. The porous carbons were used as supports for a Pt(50)−Ru(50) alloy catalyst to study their
supporting effect on the anodic performance of the catalyst in a direct methanol fuel cell (DMFC). The use
of the ordered uniform porous carbons resulted in much improved catalytic activity for methanol oxidation
in the fuel cell probably due to their high surface areas, large pore volumes, and three-dimensionally
interconnected uniform pore structures, which allow a higher degree of dispersion of the catalysts and efficient
diffusion of reagents. In general, the smaller the pore sizes in the porous carbons were, the better the catalytic
activity for methanol oxidation was. In addition, as pore sizes are getting smaller, the structural integrity with
good pore interconnection seems to be getting more important for the catalytic oxidation of methanol. Among
the porous carbons studied in this work, the one with about 25 nm in pore diameter (PtRu−C-25) showed the
highest performance with power densities of ∼58 and ∼167 mW/cm2 at 30 and 70 °C, respectively. These
values roughly correspond to ∼70 and ∼40% increase as compared to those of a commercially available
Pt−Ru alloy catalyst (E-TEK), respectively.
A highly graphitized ordered nanoporous carbon (ONC) was synthesized by using commercial mesophase pitch as carbon precursor and siliceous colloidal crystal as template. Since silica colloids of different sizes (above 6 nm) and narrow particle size distribution are commercially available, the pore size tailoring in the resulting ONCs is possible.
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