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.

Ordered porous materials containing micropores (< 2 nm), mesopores (2±50 nm), or macropores (> 50 nm) are of great interest due to their many advanced applications, which include their use as catalysts, separation systems, low-dielectricconstant materials, hydrogen-storage materials, and photonic crystals.[1] Ordered mesoporous-silica M41S materials have been prepared by employing micellar arrays of surfactant molecules as structure-directing agents for silica polymerization.[2] Colloidal crystalline arrays based on ordered aggregation of spherical-silica or latex-polymer nanoparticles have been used as templates for synthesizing new macroporous materials, including inorganic materials, [3] metals, [4] polymers, [5] and carbons. [6] Several interesting hierarchical porous materials have also been reported in which both macropores and either micro-or mesopores are incorporated into the structure. [7,8] Carbon possesses excellent chemical, mechanical, and thermal stability, and is a very interesting material for a variety of applications. Remarkable progress has been recently made in the synthesis of carbons with periodically ordered porosities using template replication with zeolites, [9] mesoporous materials, [10,11] and colloidal crystals. [6] In these syntheses, the sacrificial solid porous-silica molds were initially infiltrated with a carbon precursor, which was subsequently carbonized under non-oxidizing conditions, and then removed by dissolution in HF or NaOH solution to generate porous carbons. During the replication process, the pores and walls of the host were transformed into the walls and pores, respectively, of the resulting carbon network. Thus, the host scaffold materials are required to have interconnected pore systems, which allows for structural integrity of the templated carbon after removal of the host. Some of these periodically ordered porous carbons have demonstrated their potential as a catalyst support in fuel cells [11b,12] or as an electric double-layer capacitor (EDLC).[10d] More recently, the rapidly expanding research efforts in this field have been pushed further to produce more complex, hierarchical, multimodal porous carbons. Bimodal mesocellular carbon foams composed of uniform mesopores and ultralarge mesopores have been reported. [13] The fabrication of carbon capsules containing a hollow, macroporous core and a mesoporous shell has also been reported by replication of a solid-core/mesoporous-shell silica by nanocasting. [14] Carbon monoliths possessing a hierarchical, fully interconnected porosity have been synthesized by template replication of mesoporous/macroporous silica monoliths as host scaffolds.[15]However, the pores in these carbons were not distributed in an ordered fashion. In this work, we present the fabrication of a new type of periodically ordered, bimodal porous carbon (POBPC) framework with three-dimensionally interconnected, ordered, and uniform macropores surrounded by mesostructured walls. Scheme 1 shows the synthetic procedure for preparing the o...

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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Carbon capsules with hollow core and mesoporous shell (HCMS) structures were used as a support material for Pt(50)-Ru(50) catalyst, and the catalytic performance of the HCMS supported catalyst in the direct methanol fuel cell was described; the HCMS carbon supported catalysts exhibited much higher specific activity for methanol oxidation than the commonly used E-TEK catalyst by about 80%, proving that the HCMS carbon capsules are an excellent support for electrode catalysts in DMFC.

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