The precise control of nanostructured materials, especially porous carbon materials, has been an important challenge in materials science. The template method is an effective tool for customizing the structure of porous carbon materials, ranging from the angstrom to the nanometer scale. This account provides an overview of the recent progress in templated nanocarbons and related materials chemistry in our group. While zeolite-templated carbon is a traditional ordered microporous material, graphene mesosponge is a new type of mesoporous carbon consisting mostly of single-layer graphene walls with minimal carbon edge sites. From its distinct properties, including developed mesoporosity, high conductivity, resistance to corrosion, and exceptional mechanical flexibility, a wide range of applications become feasible, spanning battery electrodes, heat pumps, and catalyst supports. For the utilization of meticulously controlled structures in metal oxide porous nanomaterials such as ordered mesoporous silicas and anodic aluminum oxides without degradation, an effective approach is to uniformly coat them with thin carbon nanolayers. Innovative approaches have also been adopted for the creation of functional materials using ice crystals as templates, which make minimal environmental impact. Moreover, investigations into template-free synthesis techniques have been pursued, involving the precise design of organic molecules and their pyrolysis. Furthermore, our group has used temperature-programmed desorption up to temperatures of 1800 °C to quantitatively analyze edge sites in carbon materials at the ppm level. This investigation allows us to study the relationship between the carbon edge sites and the properties/functions of the carbon materials.

Graphene nanoribbons (GNRs) have received considerable attention because of their width- and edge-shape-dependent bandgap tunability. Moreover, incorporating N into GNRs has been shown to change their optical, electronic, catalytic, and magnetic properties. Therefore, the large-scale synthesis of GNRs with controlled types and numbers of N-containing functional groups is needed. However, the mass synthesis of such GNRs is challenging because of the necessity of using metal substrates as catalysts and their subsequent removal. To address this, GNRs functionalized with either pyridinic N or tertiary N were synthesized by carbonizing brominated bicyclic aromatic compounds with pyridinic N in the nanospace of metal–organic frameworks (MOFs). The use of MOFs not only increased the yield of GNRs but also increased the percentage of either pyridinic N (from 38 to 51%, i.e. +13%) or tertiary N (from 9 to 35%, i.e. +26%). Results from X-ray photoelectron spectroscopy, infrared spectroscopy, and molecular dynamics simulations using a reactive force field suggested the presence of GNR-like structures with either pyridinic N or tertiary N in the samples synthesized at 673 K. This study offers valuable information for the mass synthesis of GNRs with either pyridinic N or tertiary N.

In recent years, the introduction of defect structures, such as 5- and 7-membered rings, edges, and functional groups in carbon materials has received considerable attention because of its potential for improving their performance in various applications. In particular, 5- and 7-membered rings are among the most stable defects because they exist in the basal plane. However, the catalyst-free synthesis of carbon materials with high proportions of both 5- and 7-membered rings out of 5-, 6-, and 7-membered rings is yet to be reported. This study reports the catalyst-free synthesis of carbon materials containing a high percentage of 5- and 7-membered rings by the simple bromination and heating of azulene (Azu) comprised of only 5- and 7-membered rings. Only 31% of edges in Azu reacted after nonbrominated Azu was carbonized at 873 K, whereas a significantly higher percentage of edges in Azu (92%) reacted after brominated Azu was carbonized at the same temperature. Thus, the bromination of Azu significantly improved its reactivity, leading to a relatively low electrical resistivity. Detailed analyses of brominated and carbonized Azu using Raman spectroscopy, infrared spectroscopy, and the full width at half maximum of C1s X-ray photoelectron spectra suggested that the synthesized carbon materials consisted of graphene-like planes in which 90% of the rings were 5- and 7-membered and only 10% were 6-membered.

Single-fiber compression tests were conducted to measure the compressive strength of high-modulus carbon fibers produced from polyacrylonitrile (PAN) and mesophase pitch (MPP). The difference in the compressive fracture behaviors of PAN- and MPP-based carbon fibers was clarified by performing an in-situ void structure analysis during the compression process. The compressive strength decreased with an increase in the extent of the crystallite layers parallel to the fiber axis. In addition, the compressive strength of the MPP-based carbon fibers was significantly lower than that of the PAN-based carbon fibers. The void structure of the MPP-based carbon fibers began to change during the initial stage of compression, whereas that of the PAN-based carbon fibers remained constant during compression and was expected to deform only immediately before failure. Stress homogenization in PAN-based carbon fibers may be caused by the existence of amorphous regions between crystallites, which results in a higher compressive strength than that of MPP-based carbon fibers.