DOI: 10.1002/adma.200700699 Generation of Hierarchical Meso- and Macroporous Carbon from Mesophase Pitch by Spinodal Decomposition using Polymer Templates** By Philipp Adelhelm, Yong-Sheng Hu, Laemthong Chuenchom, Markus Antonietti, Bernd M. Smarsly ,* and Joachim Maier Recently, there has been growing interest in the synthesis of mesoporous carbons (pore size ranging from 2–50 nm) owing to the advantages offered by these materials over micropo- rous carbons for liquid transport processes, membranes and filters, as well as in chromatography and catalyst supports. [1–3] Furthermore, electrically conductive carbon matrices are used in electrochemical devices as electrode materials (such as in lithium-ion batteries, supercapacitors, and fuel cells). The use of porous carbon in the latter applications requires an optimal combination of high porosity and surface area with good transport properties. It should be emphasized that micropo- rosity is not a requirement, and is indeed undesirable for most of these applications, since micropores tend to act as deep- trap sites, thereby hindering the reversibility of underlying binding processes such as Li insertion. [4] However, a major challenge in the fabrication of tailored mesoporous carbon is the inability of current synthetic proce- dures to achieve good conductivity (i.e., extended graphene units) and mesoporosity at the same time. In general, high conductivity in carbon is obtained by high-temperature heat treatment; however, such treatment destroys the mesoporous structure due to pore collapse arising from changes in the structure of graphene units. [5] Another important trend in the field of porous materials has been the generation of hierarchical pore systems. [6–9] Such hierarchical structures are characterized by the presence of macropores (>50 nm) along with micro- and/or mesopores. The presence of macropores is desirable since these bigger pores can act as a transport system for liquids and gases, thus increasing the accessibility of the smaller pores. Hierarchical pores have been successfully established in silica gels using spinodal phase separation between poly(ethylene glycol) and silica oligomers. [10,11] This process leads to the development of well-defined mesoporosity and a bicontinuous macropore network, which has already been exploited to fabricate chro- matographic devices exhibiting superior performance, as evi- denced by simultaneous high plate numbers and short separa- tion times. [1] Recently, different strategies have been reported for the ra- tional design of mesoporous carbon materials. In the case of “hard templating”, a porous inorganic template (usually po- rous silica) is soaked with a carbon precursor such as furfuryl alcohol. After carbonization, the template is removed by dis- solution, and porous carbon with a controllable pore size is obtained. [12,13] Silica monoliths have also been templated in this fashion, exactly replicating the pore hierarchi of the tem- plate. [14,15] Recently, a modification of the hard-templating ap- proach using mesophase pitch (MP) has been reported. [16] However, clearly the hard-templating route has some inherent shortcomings and is not feasible for large-scale synthesis since it involves a complicated multistep procedure and relies on the use of harmful chemicals for the removal of the template. Thus, it is our belief that these approaches will be limited to laboratory-scale model systems. “Soft templating” is expected to be more flexible in gener- ating mesoporous carbon materials based on the principles of liquid-crystalline templating (“nanocasting”). [17,18] Recently, Zhao and co-workers have reported the formation of ordered mesoporous carbon structures by the condensation of pheno- lic precursors around micelles followed by subsequent trans- formation into the porous material by simple heat treat- ment. [19] A major challenge for both templating approaches is the choice of the precursor; the commonly used precursors (sucrose, furfuryl alcohol, or phenolic resins) are sufficiently polar to enable good compatibility with the template, but are not ideal with regards to transformation into highly conduc- tive carbon because sufficiently extended aromatic rings (i.e., large graphene rings with lateral dimensions L a and stack heights L c ) can only be obtained at relatively high tempera- tures (>1500 °C). However, heating to such high temperatures disrupts the mesopores. Additionally, these precursors carbo- COMMUNICATION 4012 © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Adv. Mater. 2007, 19, 4012–4017 – [*] Dr. B. M. Smarsly, P. Adelhelm, L. Chuenchom, Prof. M. Antonietti Max-Planck Institute of Colloids and Interfaces, Research Campus Golm 14424 Potsdam (Germany) E-mail: bernd.smarsly@phys.chemie.uni-giessen.de Dr. B. M. Smarsly University of Giessen, Institute of Physical Chemistry Heinrich-Buff-Ring 58, 35392 Giessen (Germany) Dr. Y.-S. Hu, Prof. J. Maier Max-Planck-Institute for Solid State Research Heisenbergstr.1, 70569 Stuttgart (Germany) [**] Financial support from Merck KGaA is gratefully acknowledged. The authors are indebted to the Max Planck Society, and also acknowl- edge support under the framework of the ENERCHEM project. We thank Mitsubishi Chemical Company for providing the mesophase pitch AR. Supporting Information is available online from Wiley In- terScience or from the author.