Templated carbons

The pores of the silica template can be filled by carbon from a gas or a liquid phase. One may consider an insertion of pyrolytic carbon from the thermal decomposition of propylene or by an aqueous solution of sucrose, which after elimination of water requires a carbonization step at 900°C. The carbon infiltration is followed by the dissolution of silica by HF. The main attribute of template carbons is their well sized pores defined by the wall thickness of the silica matrix. Application of such highly ordered materials allows an exact screening of pores adapted for efficient charging of the electrical double layer. The electrochemical performance of capacitor electrodes prepared from the various template carbons have been determined and are tentatively correlated with their structural and microtextural characteristics. 

The total surface area of the template carbons prepared by sucrose impregnation is significantly higher than the surface area of the corresponding silica template (Table 2), that confirms the formation of micropores during the carbonization. Just an opposite tendency is observed... 

Keren K, Berman RS, Buchstab E, Sivan U, Braun E (2003). DNA-templated carbon nanotube field-effect transistor. Science 302 1380-1382. 

The template carbons demonstrate interesting performance in electric double layer capacitors [109], especially the mesoporous carbons prepared using MgO as the template [105,110], Asymmetric electric double layer capacitors constructed from these mesoporous carbons coupled with amicroporous activated carbon display high capacitance and high rate performance [111]. 

Novel, inexpensive synthesis routes for producing materials with precisely controlled nanotexture must be developed to improve the performance of batteries and electrochemical capacitors, as well as to enable new electrochemical applications of carbons. Two alternatives, carbide-derived carbon (CDC) and templated carbon, have shown a promise to offer the requisite control necessary to push device performance to the next level and will be explored in this chapter. 

FIGURE 3.15 Scheme of the template carbonization using zeolite Y. 

Bandosz, T.J., Jagiello, J., Putyera, K., and Schwarz, J.A. Pore structure of carbon-mineral nanocomposites and derived carbons obtained by template carbonization. Chem. Mater. 8, 1996 2023-2029. 

Kodama, M., Yamashita, J., Soneda, Y., Hatori, H., Nishimura, S., and Kamegawa, K. Structural characterization and electric double layer capacitance of template carbons. Mater. Sci. Eng. B 108, 2004 151-161. 

---