"Space—the final frontier." This preamble to a well-known television series captures the challenge encountered not only in space travel adventures, but also in the field of porous materials, which aims to control the size, shape and uniformity of the porous space and the atoms and molecules that define it. The past decade has seen significant advances in the ability to fabricate new porous solids with ordered structures from a wide range of different materials. This has resulted in materials with unusual properties and broadened their application range beyond the traditional use as catalysts and adsorbents. In fact, porous materials now seem set to contribute to developments in areas ranging from microelectronics to medical diagnosis.

Ordered porous materials for emerging applications

Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.

Carbon Materials for Chemical Capacitive Energy Storage

Ordered carbon molecular sieves exhibiting Bragg diffraction of X-ray lines have been synthesized for the first time, using mesoporous silica molecular sieves as the template. Sucrose was converted to carbon inside the mesopores of the silica molecular sieves through a mild carbonization process using a sulfuric acid catalyst. The carbon molecular sieves were obtained after the removal of the silica framework using an aqueous solution of sodium hydroxide. The X-ray diffraction, transmission electron microscopy, and pore size analysis showed that the structure of the carbon molecular sieves consisted of a three-dimensional regular array of uniform mesopores 3 nm in diameter. The structure was not simply a negative replica of the used silica template, but the synthesis mechanism involved the unique transformation into a new ordered array that was triggered by the removal of the silica frameworks. The highly ordered mesoporous texture suggested its scientific and technological importance as a new shape-selec...

Synthesis of highly ordered carbon molecular sieves via template-mediated structural transformation

Electrical energy storage (EES) is one of the most critical areas of technological research around the world. Storing and efficiently using electricity generated by intermittent sources and the transition of our transportation fleet to electric drive depend fundamentally on the development of EES systems with high energy and power densities. Supercapacitors are promising devices for highly efficient energy storage and power management, yet they still suffer from moderate energy densities compared to batteries. To establish a detailed understanding of the science and technology of carbon/carbon supercapacitors, this review discusses the basic principles of the electrical double-layer (EDL), especially regarding the correlation between ion size/ion solvation and the pore size of porous carbon electrodes. We summarize the key aspects of various carbon materials synthesized for use in supercapacitors. With the objective of improving the energy density, the last two sections are dedicated to strategies to increase the capacitance by either introducing pseudocapacitive materials or by using novel electrolytes that allow to increasing the cell voltage. In particular, advances in ionic liquids, but also in the field of organic electrolytes, are discussed and electrode mass balancing is expanded because of its importance to create higher performance asymmetric electrochemical capacitors.

Carbons and Electrolytes for Advanced Supercapacitors

In this review, the progress made in the last ten years concerning the synthesis of porous carbon materials is summarized. Porous carbon materials with various pore sizes and pore structures have been synthesized using several different routes. Microporous activated carbons have been synthesized through the activation process. Ordered microporous carbon materials have been synthesized using zeolites as templates. Mesoporous carbons with a disordered pore structure have been synthesized using various methods, including catalytic activation using metal species, carbonization of polymer/polymer blends, carbonization of organic aerogels, and template synthesis using silica nanoparticles. Ordered mesoporous carbons with various pore structures have been synthesized using mesoporous silica materials such as MCM-48, HMS, SBA-15, MCF, and MSU-X as templates. Ordered mesoporous carbons with graphitic pore walls have been synthesized using soft-carbon sources that can be converted to highly ordered graphite at high temperature. Hierarchically ordered mesoporous carbon materials have been synthesized using various designed silica templates. Some of these mesoporous carbon materials have successfully been used as adsorbents for bulky pollutants, as electrodes for supercapacitors and fuel cells, and as hosts for enzyme immobilization. Ordered macroporous carbon materials have been synthesized using colloidal crystals as templates. One-dimensional carbon nanostructured materials have been fabricated using anodic aluminum oxide (AAO) as a template.

Recent Progress in the Synthesis of Porous Carbon Materials

An attempt was made to prepare porous carbon by using the channels of Y zeolite as a template. Poly(acrylonitrile) and poly(furfuryl alcohol) were carbonized in the zeolite channels and the resultant carbon/zeolite complexes were subjected to acid treatment in order to extract carbon from the zeolite framework. In addition, pyrolytic carbon deposition in the channels was carried out by exposing the zeolite to propylene at high temperature, and then the carbon was liberated in the same manner as above. The morphology and structure of the carbon prepared in the channels were characterized, and the results were discussed in relation to the morphology and structure of the original zeolite template. It was found that the microscopic morphology of the resultant carbons reflects that of the corresponding zeolites. All of these carbons are highly porous, and some of the CVD carbons have BET surface areas as high as >2000 m2/g.

Formation of New Type of Porous Carbon by Carbonization in Zeolite Nanochannels

On March 11, 2011 at 14:46 (Friday), a massive magnitude-9.0 earthquake attacked large areas of northeastern Japan, including Sendai City. The huge earthquake generated catastrophic tsunamis, leading to unprecedented disasters in the seacoast areas of the Tohoku region (about 20,000 dead and missing persons). Upon this earthquake, in Tohoku University Medical Library, a 3-storey earthquake-resistant building, most of books fell down from bookshelves on the second and third floors, but the bookshelves remained steady because of the effective fixation. Many piles of fallen books blocked up the walkways and the narrow passages between the bookshelves; namely, books are easily transformed to dangerous weapons in a shaking building. Fortunately, all library staffs and users evacuated outside the building without even a scratch. Importantly, we were able to open the first floor of the Medical Library on March 14 (Monday), because the first floor has been used for the Learning Commons, with open space for group meetings. We thus provided students, medical staffs, and faculty members with the comfortable place during the early stage of the disasters. In fact, medical staffs and faculty members worked hard over weekend to deal with many patients and clear the post-quake confusions. Moreover, electricity, gas, or water supply was not yet restored in most areas of Sendai City. In the earthquake-prone zones, the Medical Library should function as a facility that not only enhances information gathering but also provides the place like an oasis of relaxation for students and medical staffs upon great earthquakes.

Messages from a medical library in the earthquake-prone zone.

In this paper, we consider a special class of the surfaces in 3-sphere de(cid:12)ned by one-parameter families of great circles. We give a generic classi(cid:12)cation of singularities of such surfaces and investigate the geometric meanings from the view point of spherical geometry.

Takayuki Nagai

Papers

Formation of New Type of Porous Carbon by Carbonization in Zeolite Nanochannels

Messages from a medical library in the earthquake-prone zone.

Great surfaces in the three-sphere