Ordered Porous Carbons with Tunable Pore Sizes as Catalyst Supports in Direct Methanol Fuel Cell

Abstract

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.

Novel Mesoporous Carbon Supports for PEMFC Catalysts

“…This may be due to a disordered arrangement of the 12 nm silica colloids around the mesophase pitch carbon during synthesis or due to the partial collapse of the carbon structure during carbonization, which has been previously suggested to occur for imprinted carbons with pores <50 nm in diameter [41,42]. The fact that the pores of CIC-15 are not tightly packed would produce a lower surface area than expected, thus confirming the results shown in Figure 4.…”

Recent Progress in the Synthesis of Porous Carbon Materials

“…The same group further controlled the pore size of the macroporous carbon materials in the range of 10-100 nm by using silica spheres with various particle sizes, and conducted detailed studies on their use as the electrodes in fuel cells. [138] The Yu and Jaroniec groups reported the preparation of highly graphitized ordered mesoporous carbons using commercial mesophase pitch as a carbon precursor and silica colloidal crystals as templates. [139] The synthesis of the graphitized ordered nanoporous carbon was carried out by the incorporation of mesophase pitch dissolved in quinoline in the interstitial space of the silica templates under a static vacuum.…”

Carbon Nanotubes Decorated with Pt Nanocubes by a Noncovalent Functionalization Method and Their Role in Oxygen Reduction

“…[18] The activity of Pt-based catalysts could be improved when on carbon supports. [19] Pt-based catalyst are often deposited onto a variety carbon supports, including carbon black, [20] carbon nanofibers, [21] ordered porous carbons, [22] and carbon nanotubes (CNTs). [23] Among these materials, CNTs are particularly interesting because they have unique and structure-dependent mechanical and electronic properties.…”