Quantitative study on catalysis of unpaired electrons in carbon edge sites

Wakabayashi, Keigo; Yoshii, Tadashi; Nishihara, Hirotomo

doi:10.1016/j.carbon.2023.118069

Cited by 10 publications

(5 citation statements)

References 54 publications

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“…Another interesting feature of ZTC is its abundant edge sites. We have observed enhanced catalytic activity in ZTC originating from radicals located at its edge sites [42].…”

Section: Zeolite-templated Carbons (Ztc)mentioning

confidence: 85%

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Progress in templated nanocarbons and related materials chemistry

Nishihara

2024

Carbon Rep.

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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.

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“…Another interesting feature of ZTC is its abundant edge sites. We have observed enhanced catalytic activity in ZTC originating from radicals located at its edge sites [42].…”

Section: Zeolite-templated Carbons (Ztc)mentioning

confidence: 85%

“…the electrochemical performance of lead-carbon batteries [108], and radical-mediated oxidation catalysis [42].…”

Section: Carbon Reportsmentioning

confidence: 99%

Progress in templated nanocarbons and related materials chemistry

Nishihara

2024

Carbon Rep.

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“…This gaseous release, characterized by the emission of CO2 (mainly around 400 °C) and CH4 (mainly around 500 °C), eventually resulted in significant weight changes [21,22]. The weight changes observed in Stage 2 can be attributed to the release of CO at 700-1200 °C and H2 at 600-1500 °C [23,24]. The weight change was less significant in Stage 2 because part of the oxygen-and hydrogen-containing functional groups was already released during Stage 1.…”

Section: Carbonization Yield Measured Using Tga and A Tube Furnacementioning

confidence: 99%

Changes in Functional Groups and Crystal Structure of Coal Tar Pitch with Respect to Carbonization Temperature

Lee,

Roh

2024

Crystals

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In this study, changes in the microstructure of coal-tar pitch (CTP) during successive processes, including pyrolysis, polycondensation, and crystallization, were examined in connection with the resulting variations in structure factors, as measured by X-ray diffraction (XRD) analysis, and functional groups, as confirmed by Fourier transform infrared (FTIR) spectroscopy. To this end, four zones were defined based on variations in crystallinity, which were indicated by d002 and Lc. Each zone was further characterized by interpreting crystallinity development in relation to changes in functional groups and specimen height. At around 400 °C, polycondensation occurred as the C-Har and C-Hal peaks decreased in intensity. These peak reductions coincided with the formation of mesophase spheres, resulting in enhanced crystallinity. Subsequently, at around 500 °C, the peak intensity of C-H and COOH decreased, which was attributed to the release of large amounts of gases. This led to sharp volume changes and a temporary reduction in crystallinity. All these results suggest that changes in the functional groups of CTP at lower temperatures (600 °C or less) during the carbonization process are closely associated with variations in its crystallinity. The major findings of the present study provide valuable insights for designing highly effective processes in the manufacturing of synthetic graphite blocks using CTP as a binder material, including by selecting appropriate temperature ranges to minimize volume expansion and crystallinity degradation and determining the lowest possible carbonization temperature to ensure adequate binder strength.

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“…However, it is acknowledged that the SV defect is known to be extremely reactive and not present at room temperature. [52][53][54] Therefore, to avoid computationally costly spin polarized calculations we have excluded the SV defect from our capacitance calculations. The calculated defect formation energies are inherently large, indicating they are not thermodynamically favourable.…”

Section: J U S T a C C E P T E Dmentioning

confidence: 99%