The structure and electronic properties of graphene are fundamental to those of carbon materials and are significantly influenced by the presence of nonideal structures such as defects, impurities, and edges, which can be controlled through the functionalization of graphene by chemical species. According to the energy scale of the interactions between graphene and these species, three routes for the functionalization of graphene were examined: the proximity effects of adsorbed molecules, ion irradiation, and covalent bonding. The sign and concentration of the charge carrier, and its scattering in graphene were precisely controlled by the adsorption of molecules on it or the chemical modification of the surface of the supporting substrate. Irradiation with an ion beam modified the electronic structure of graphene and its electrical conductivity in a well-defined manner. Direct chemical modification induced the formation of covalent bonds with guest species and significantly changed the topology of the honeycomb lattice of graphene, resulting in localized spin magnetism and catalytic activity originating from spin-polarized localized states emerging at the Fermi energy.

A wide variety of surface functional groups, such as oxygen-containing ones and hydrogen, exist at the graphene edge sites of carbon materials. Because the presence of these functional groups greatly affects the chemical properties of carbon-based materials produced from them, knowledge of the edge site state is essential to understand carbon chemistry. This review describes the analyses of edge sites and carbon-material structures by temperature-programmed desorption (TPD). Deuterium labeling of the protonic hydrogen of oxygen-containing functional groups enables the precise identification of the chemical structure of edge sites. Furthermore, the spatial distribution of edge sites in the carbon structure can be determined by the kinetic analysis of H₂ desorption spectra collected at temperatures above 1000 °C. The average size of graphene sheets forming the carbon can be estimated from the number of edge sites. The TPD-based analytical approaches described in this paper help provide a better understanding of the carbon structure at the molecular level.

The electronic resistance of composite electrodes for lithium-ion batteries has a non-negligible effect on the charge–discharge performance at high rates. In order to obtain an electrode with a high-rate performance it is important that conductive materials, such as acetylene black (AB), in the electrode slurry form a good electron conduction network. This study evaluated the electron conduction network of various electrode slurries made using different processes and with different solid contents using electronic conductivity measurements of the electrode slurries. The conductivity of the slurry showed a correlation with the rate performance. Depending on the production method and solid content, the conductivity of the slurry changed. The results suggest that the electron conduction network of the slurry is modified by collisions between the AB and active material particles during kneading and by stirring the slurry with excess solvent during dispersion. Measuring the conductivity of the slurry is expected to help determine the conditions of its manufacture.

Pyridinic nitrogen-containing carbon materials are expected to have excellent performance as electrodes and catalysts. Carbon materials containing only pyridinic nitrogen have been synthesized in recent years, and the use of two-fused-ring aromatic compounds as precursors enabled the synthesis of relatively inexpensive pyridinic nitrogen-containing carbon materials. However, a two-fused-ring aromatic compound such as isoquinoline (IQ) required a relatively high temperature (973 K) for carbonization, causing C–N bond cleavage, and the percentage of pyridinic nitrogen was relatively low: 52% of the N atoms are pyridinic. This study synthesized pyridinic nitrogen-containing carbon materials from six brominated IQs. The bromination of IQs lowered the carbonization temperatures to 673–873 K, which helped avoid the decomposition of the pyridinic nitrogen. Among these six precursors, the one with two bromine substitutions (1,4-dibromoisoquinoline) had the highest percentage of pyridinic nitrogen (65%) at 773 K. The factors that increase the percentage of pyridinic nitrogen are (1) avoiding the formation of a 1,10-phenanthroline-like structure during dimerization, (2) avoiding the formation of N–H and promoting the scission of the formed C–N in dimers formed after C=C coupling at bromine-substituted positions between precursors, and (3) forming a more ordered six-membered ring structure by the introduction of two or more highly reactive bromines.

Sucrose was mixed with melamine and urea, and the mixture was activated by zinc chloride to increase the number of amine functional groups and quaternary nitrogen (N–Q) atoms on the sample surface and to improve phosphate ion adsorption. The highest amount of phosphate ion adsorption (0.40 mmol/g) was obtained when melamine, urea, sucrose, and zinc chloride were mixed in 1 : 1 : 2 : 2 weight ratios and activated three times at 550 °C. The total amount of nitrogen in the sample decreased as the number of activation cycles increased, but the number of protonated amine functional groups and N–Q that contributed to phosphate adsorption increased. The specific surface area increased with the number of activation cycles, with a maximum value of approximately 278 m²/g. This was due to the removal of hydrogen and oxygen ions from the raw materials by the dehydration reaction using zinc chloride at high temperatures, resulting in the formation of pores. Maximum adsorption was observed when the equilibrium solution pH (pH_e) was 4.0, indicating that the adsorbent has a high adsorption performance in acidic regions. The adsorption isotherm was fitted to the Langmuir model, indicating monolayer adsorption, with an estimated maximum amount of phosphate adsorption (X_m) of 0.61 mmol/g.

Boron/carbon (B/C) materials with a graphite-like layer structure were prepared and characterized and used as anodes in lithium (Li) ion batteries (LIBs). Li was electrochemically intercalated into and de-intercalated from these materials. The B/C material with the composition BC_7.9 showed the highest reversible capacity (about 580 mA h/g) among the materials prepared. Ex-situ x-ray diffraction indicated that the intercalation of Li into the layers of the B/C materials occurred during discharge to form a first-stage intercalation compound. ⁷Li and ¹¹B-NMR observations suggested that the intercalated Li interacted with B in the materials which resulted in large capacities of the B/C materials as LIB anodes.