Meso/macroporous carbons

The physical and chemical activation processes have been generally employed to prepare the porous carbons.18"35 However, the pore structures are not easily controlled by the activation processes and the size of the pores generated by the activation processes is limited to the micropore range only. Recently, much attention has been paid to the synthesis of meso/macroporous carbons with various pore structures and pore size distributions (PSD) by using various types of such inorganic templates as silica materials and zeolites.17,36 55... 

The meso/macroporous carbons have attracted much attention in their application as electrode materials in EDLCs, since the meso/macropores promote the formation of an effective doublelayer or the transfer of ions into the pores, resulting in the increases in the electrolyte wettability and the rate capability.67,68 In this regard, there has been considerable research targeted towards developing the synthetic methods of novel meso/macroporous carbons.17,36"55,69 72 Various types of such inorganic templates as silica materials and zeolites are widely used for the synthesis of the meso/macroporous carbons, since it was revealed17,36"55 that these inorganic templates contribute to the formation of the meso/macropores with various pore structures and broad PSD. 

Figure 1. Plots of differential pore volume against pore diameter calculated from the N2 gas adsorption isotherms obtained from meso/macroporous carbon specimens I (-0-), II (- -), and III (-A-) using Barrett-Joyner-Halenda (BJH) method. Reprinted with permission from G. -J. Lee and S. -I. Pyun, Carbon, 43 (2005) 1804. Copyright 2005, with permission from Elsevier.

The present article first provided the brief overview of the synthetic methods of the porous carbons. In order to prepare the microporous carbons with high surface area, the physical/chemical activation methods have been widely used for a long time.18"35 Recently, the meso/macroporous carbons with various pore structures are prepared by templating methods by using various templates and changing sol-gel reaction conditions, e.g., pH, amount of template, and gelation temperature.17,36 55... 

Liang C, Dai S (2009) Dual phase separation for synthesis of bimodal meso-/macroporous carbon monoliths. Chem Mater 21 2115-2124... 

Alvarez S, Esquena J, Solans C, Fuertes AB (2004) Meso/macroporous carbon monoliths from polymeric foams. Adv Eng Mater 6 897... 

Chu, H., Zhang, Z., Liu, Y., Leng, J., 2014. Self-heating fiber reinforced polymer composite using meso/macropore carbon nanotube paper and its application in deidng. Carbon 66,... 

In an experiment carried out with 100 mg/1 methylene blue concentration the behaviour was the same as described before, but, there was a time in which SC-155 reached the saturation and the material stopped the adsorption the AC-ref instead continued the adsorption at longer times due to its higher carbon contents. Then, the great difference in adsorption kinetics observed between SC-155 and AC-ref is justified by the more expanded structure of carbon microdomains of SC-155 than the reference, and by the higher radius of meso-macropores observed for the SC-155 the last point provides an easy access of molecules to be adsorbed into the grains of the material, minimizing diffusional problems. 

Shiraishi, S., Kurihara, H., Shi, L., Nakayama, T., and Oya, A. Electric double-layer capacitance of meso/macroporous activated carbon fibers prepared by the blending method. J. Electrochem. Soc. 149, 2002 A855-A861. 

They consist of a thin layer (<10 fxm) of a nanoporous (3-1OA) carbon film supported on a meso-macroporous inorganic solid (alumina) or on a carbonized polymeric structure [15]. They are produced by pyrolysis of polymeric films. The following two types of membranes are produced ... 

It should be noted that the t-plot analysis shows a very small amount of micropores in the sample studied, which is due to the use of the mesophase pitch as the carbon precursor. It is known that many precursors, e.g., sucrose and polyfurfuryl alcohol, infiltrate well siliceous templates but after carbonization give meso- or macroporous carbons with complementary microporosity. This is not the case for the mesophase pitch, which is used to synthesize carbon fibers that are nonporous materials. 

The nanoporous carbon membrane consists of a thin layer (<10pm) of a nanoporous (3-7 A) carbon film supported on a meso-macroporous solid such as alumina or a carbonized polymeric structure. They are produced by judicious pyrolysis of polymeric films. Two types of membranes can be produced. A molecular sieve carbon (MSC) membrane contains pores (3-5 A diameters), which permits the smaller molecules of a gas mixture to enter the pores at the high-pressure side. These molecules adsorb on the pore walls and then they diffuse to the low-pressure side of the membrane where they desorb to the gas phase. Thus, separation is primarily based on differences in the size of the feed gas molecules. Table 7 gives a few examples of separation performance of MSC membranes. ° Component 1 is the smaller component of the feed gas mixture. 

Figure 4.15 shows the discharge and charge curves of the prepared three-dimensionally ordered macroporous carbon with controlled meso pores in Et NBPy PC at various currents. From the results, the electric capacity of this carbon was estimated to be 90 Fg . 

In order to prepare the meso/macropores with the size of several decades of nanometers, the silica colloids have been freqnently nsed as a template since the colloidal silica templates are reprodncible and effective for the synthesis of the porons carbons with larger pore size, broad PSD, high pore volnme, and high snrface area by sol-gel The silica gels are... 

Kim et al. [64] analyzed porous carbon by using colloidal sUica particles as templates. Carbon with micro, meso and macropores were obtained modifying the initial pH of the carbon precursor solutions. This fabrication method produces materials with narrow pore size distribution in a broad range of pore size. The fuel cell test showed better DMFC performance for carbons with high meso-macropore area with large pore than that with micropores. Again, this effect was attributed to the fact that meso and macropores produce a favorable dispersion of PtRu metal species and allow the access of perfluorosulfonate ionomer for the formation of the triple phase boundary. 

Adelhehn P, Hu Y-S, Chuenchom L, Antonietti M, Smarsly BM, Maier J (2007) Generation of hierarchical meso- and macroporous carbon from mesophase pitch by spinodal decomposition using polymer templates. Adv Mater 19 4012-4017... 

Active carbons Carbon molecular sieves Adsorption polymers Silica gels Narrow Wide Porous glasses Micro-/meso-/ macropores Zeolites Bleaching earth Activated alumina... 

Explains the underlying chemistry of methods for customizing the properties of micro-, meso-, and macroporous carbons... 

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