Templated porous carbon applications

Several reviews covering the synthesis, properties and applications of porous carbons, especially mesoporous carbon materials, can be found in the literature. In this chapter, we summarise the recent developments in the synthesis and characterisation of templated porous carbon materials. Particular attention is paid to the synthesis of structurally ordered porous carbon materials with narrow pore size distribution via both hard and soft template methods. We especially emphasise those so-called breakthroughs in the preparation of porous carbon materials. The chapter is divided into three sections according to the pore size of carbon materials we first consider the synthesis of microporous carbon materials using zeolites and clays as hard template, then summarise the preparation of mesoporous carbon materials via both hard template and self-assembly... 

The surface chemistry of a carbon is known to play a crucial role in many applications, most notably in adsorption and catalysis [91-94]. It has been observed that the surface of templated porous carbons mainly has oxygen-containing functional groups, such as carboxyl, carbonyl, quinone, and hydroxyl [76,94,95]. Such groups, especially the carboxyls, can be eliminated by high-temperature... 

These porous carbons, referred to as MgO-templated carbons, have been applied in various areas such as electrodes for electric double-layer capacitors [88], as absorbents for gasoline, and as anodes for lithium ion batteries. The application of these MgO-templated porous carbons has been reviewed elsewhere in Japanese [89]. 

Since the discovery of ordered mesoporous materials, researchers have explored many possible applications that can take advantage of the unique compositional or structural features of mesoporous materials. In addition to apphcations in traditional areas such as catalysis, separation, and ion exchange, new applications that might involve mesoporous materials include stationary phases in HPLC, bio and macromolecular separations, low dielectric constant materials, enzyme immobilization, optical host materials, templates for fabrication of porous carbons, and reactions in confined enviromnents. 

Interestingly, porous materials can act as templates for synthesizing other porous materials, as, for example, the application of MOFs (Liu et al., 2008) and organo-modified LDHs (Leroux et al., 2006) for porous carbon synthesis. 

The relevant properties of MOFs have prompted their use for catalysis, gas storage, and separation (Janiak, 2003 Chun et al., 2005 Kaye and Long, 2005 Rowsell and Yaghi, 2006), as well as for fuel cells (Mueller et al., 2006), Li-based batteries (Li et al., 2006 Ferey et al., 2007), and electrocatalysis (Wang et al., 2008). Conversely, MOFs can be synthesized electrochemically, as described by Mueller et al. (2006). MOFs are indirectly related with other electrochemical applications acting as a template for the synthesis of porous carbon to be applied as double-layer electrochemical capacitor (Liu et al., 2008). 

Indeed, the past ten years have witnessed rapid advances in using template carbonisation to produce ordered porous carbon materials, ranging from microporous to mesoporous and macroporous carbons. The template carbonisation method has thus been regarded as one of the most effective approaches to prepare porous carbon materials with desirable physical and chemical properties. It has, therefore, opened up new opportunities in making novel porous materials for a wide range of applications. 

Alternative interesting applications for porous carbon materials have been recently reported. For example, porous carbons prepared from the large mesopore Fniim silica (KlT-5) demonstrated a superior ability to separate the tea components catechin and tannic add, compared to other p>orous materials, such as activated carbons and mesoporous silica [23]. Porous carbon nitride with a large surface area has been prepared using well-ordered mesoporous silica as a template for the polymerization between ethylenediamine and carbon tetrachloride [24]. In this case, the metal-free carbon nitride was able to function as an efficient basic catalyst for transesterification reactions. 

In this chapter, we provide an overview of the recent research and development in the preparation, characterization, and application of novel porous carbons using both the endotemplate and the exotemplate methods. A discussion of zeolite templates for microporous carbons is followed by that of ordered mesoporous silica templates for OMCs, nanoparticle templates for mesoporous carbons, sol-gel processed porous carbons, self-assembled colloidal crystal templates for ordered macroporous carbons, and colloidal sphere templates for hollow carbon spheres, as well as other templating approaches to preparing carbon nanostructures. Then,... 

The tailor-designed physicochemical properties of porous carbons prepared using the template method make them promising candidates in many applications, including adsorption, catalysis, chromatography, energy storage and conversion, and photonics. 

FIGURE 3.11 SEM images of the colloidal silica composite templates (insets) and the corresponding carbon replicas prepared by (a) volume templating and (b) surface templating, using 250 nm silica spheres. (Reprinted with permission from Yu, J. S. et al. 2002. Fabrication of ordered unifrom porous carbon networks and thir application to a catalyst supporter. Journal of the American Chemical Society 124 9382-9383. Copyright (2002). The American Chemical Society.)... 

Porous carbon materials with high surface areas and pore volumes prepared from porous inorganic templates are of current interest for energy storage, gas separation, heterogeneous catalysis, and many other applications including water purification, catalyst support as well as electrode material... 

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