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15. Preface for ITICAT2023

Author

Li, Hongjiao, primary, Yoshii, Takeharu, additional, Zhang, Cuijuan, additional, Kawi, Sibudjing, additional, and Li, Yongdan, additional

Published
2024
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19. Probing Basal and Prismatic Planes of Graphitic Materials for Metal Single Atom and Subnanometer Cluster Stabilization.

Author

Vidal, Mathieu, Pandey, Jyoti, Navarro‐Ruiz, Javier, Langlois, Joris, Tison, Yann, Yoshii, Takeharu, Wakabayashi, Keigo, Nishihara, Hirotomo, Frenkel, Anatoly I., Stavitski, Eli, Urrutigoïty, Martine, Campos, Cristian H., Godard, Cyril, Placke, Tobias, del Rosal, Iker, Gerber, Iann C., Petkov, Valeri, and Serp, Philippe

Subjects
CARBON-based materials, HETEROGENEOUS catalysis, HOMOGENEOUS catalysis, ATOMIC clusters, CATALYTIC hydrogenation, METAL clusters, RHODIUM catalysts
Abstract

Supported metal single atom catalysis is a dynamic research area in catalysis science combining the advantages of homogeneous and heterogeneous catalysis. Understanding the interactions between metal single atoms and the support constitutes a challenge facing the development of such catalysts, since these interactions are essential in optimizing the catalytic performance. For conventional carbon supports, two types of surfaces can contribute to single atom stabilization: the basal planes and the prismatic surface; both of which can be decorated by defects and surface oxygen groups. To date, most studies on carbon‐supported single atom catalysts focused on nitrogen‐doped carbons, which, unlike classic carbon materials, have a fairly well‐defined chemical environment. Herein we report the synthesis, characterization and modeling of rhodium single atom catalysts supported on carbon materials presenting distinct concentrations of surface oxygen groups and basal/prismatic surface area. The influence of these parameters on the speciation of the Rh species, their coordination and ultimately on their catalytic performance in hydrogenation and hydroformylation reactions is analyzed. The results obtained show that catalysis itself is an interesting tool for the fine characterization of these materials, for which the detection of small quantities of metal clusters remains a challenge, even when combining several cutting‐edge analytical methods. [ABSTRACT FROM AUTHOR]

Published
2024
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20. Rational bottom-up synthesis of sulphur-rich porous carbons for single-atomic platinum catalyst supports.

Author

Chida, Koki, Yoshii, Takeharu, Kawaguchi, Ryo, Inoue, Masataka, Tani, Fumito, Sobue, Tatsuki, Ohtani, Shunsuke, Kato, Kenichi, Ogoshi, Tomoki, Nakahata, Shoko, Kamiya, Kazuhide, and Nishihara, Hirotomo

Subjects
*PROTON exchange membrane fuel cells, *SUSTAINABLE chemistry, *PLATINUM catalysts, *CARBON-based materials, *CATALYST supports, *PLATINUM nanoparticles, *PLATINUM
Abstract

Single-atomic metal catalysts are attractive for green chemistry in terms of their outstanding catalytic performance and savings in precious metal usage owing to maximized metal utilization, including anode catalysts in polymer electrolyte fuel cells (PEFCs). Heteroatom-doped porous carbons are extensively used as supports, where the heteroatoms contribute to the immobilization of single-atomic metals. However, high-content doping of heteroatoms, especially sulphur (S), into carbon supports is still challenging because S species can be readily desorbed during heat treatment. Herein, we present a bottom-up fabrication approach for S-rich porous carbons from molecular precursors via a thermal polymerization process. A simple carbonization of molecules with thermally stable S-containing building blocks and polymerizable ethynyl moieties at 900 °C yields microporous carbon materials with record-high S content (over 15 wt%). The abundant S species function as an effective anchoring site for single-atomic platinum (Pt) species. Toward anode catalysts in PEFCs, the prepared single-atomic Pt catalysts efficiently promote the electrochemical hydrogen oxidation reaction, whose activity is comparable to that of commercial Pt/C, despite the significantly low Pt loading amount. [ABSTRACT FROM AUTHOR]

Published
2024
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21. Prominent structural dependence of quantum capacitance unraveled by nitrogen-doped graphene mesosponge

Author

Tang, Rui, Aziz, Alex, Yu, Wei, Pan, Zheng-Ze, Nishikawa, Ginga, Yoshii, Takeharu, Nomura, Keita, Taylor, Erin E, Stadie, Nicholas P, Inoue, Kazutoshi, Kotani, Motoko, Kyotani, Takashi, Nishihara, Hirotomo, Tang, Rui, Aziz, Alex, Yu, Wei, Pan, Zheng-Ze, Nishikawa, Ginga, Yoshii, Takeharu, Nomura, Keita, Taylor, Erin E, Stadie, Nicholas P, Inoue, Kazutoshi, Kotani, Motoko, Kyotani, Takashi, and Nishihara, Hirotomo

Abstract

Porous carbons are important electrode materials for supercapacitors. One of the challenges associated with supercapacitors is improving their energy density without relying on pseudocapacitance, which is based on fast redox reactions that often shorten device lifetimes. A possible solution involves achieving high total capacitance (Ctot), which comprises Helmholtz capacitance (CH) and possibly quantum capacitance (CQ), in high-surface carbon materials comprising minimally stacked graphene walls. In this work, a templating method is used to synthesize 3D mesoporous graphenes with largely identical pore structures (≈2100 m2 g−1 with an average pore size of ≈7 nm) but different concentrations of oxygen-containing functional groups (0.3–6.7 wt.%) and nitrogen dopants (0.1–4.5 wt.%). Thus, the impact of the heteroatom functionalities on Ctot is systematically investigated in an organic electrolyte excluding the effect of pore structures. It is found that heteroatom functionalities determine Ctot, resulting in the cyclic voltammetry curves being rectangular or butterfly-shaped. The nitrogen functionalities are found to significantly enhance Ctot owing to increased CQ.

Published
2024

22. Ordered Carbonaceous Framework Synthesized from Hexaazatrinaphthylene with Enediyne Groups via Solid-State Bergman Cyclization Reaction

Author

Sano, Yuki, Toyoda, Ryojun, Chida, Koki, Yoshii, Takeharu, Nishihara, Hirotomo, Nishina, Yuta, Asanoma, Daisuke, Takaishi, Shinya, Sugimoto, Kunihisa, and Sakamoto, Ryota

Abstract

Porous materials synthesized through bottom-up approaches, such as metal–organic frameworks and covalent organic frameworks, have attracted attention owing to their design flexibility for functional materials. However, achieving the chemical and thermal stability of these materials for various applications is challenging considering the reversible coordination bonds and irreversible covalent bonds in their frameworks. Thus, ordered carbonaceous frameworks (OCFs) emerge as a promising class of bottom–up materials with good periodicity, thermal and chemical stability, and electrical conductivity. However, a few OCFs have been reported owing to the limited range of precursor molecules. Herein, we designed a hexaazatrinaphthylene-based molecule with enediyne groups as a precursor molecule for synthesizing an OCF. The solid-state Bergman cyclization of enediyne groups at a low temperature formed a microporous polymer and an OCF, exhibiting redox activity and demonstrating their potential for electrochemical applications. The microporous polymer was used as an active material in sodium-ion batteries, while the OCF was used as an electrochemical capacitor. These findings illustrate the utility of the Bergman cyclization reaction for synthesizing microporous polymers and OCFs with a customizable functionality for broad applications.

Published
2024
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23. Thermodynamically Favorable Route to the Synthesis of Nanoporous Graphene Templated on CaO via Chemical Vapor Deposition

Author

Pirabul, Kritin, primary, Zhao, Qi, additional, Sunahiro, Shogo, additional, Pan, Zheng-Ze, additional, Yoshii, Takeharu, additional, Hayasaka, Yuichiro, additional, Hoi-Sing Pang, Eddie, additional, Crespo-Otero, Rachel, additional, Di Tommaso, Devis, additional, Kyotani, Takashi, additional, and Nishihara, Hirotomo, additional

Published
2024
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25. A thermodynamically favorable route to the synthesis of nanoporous graphene templated on CaO via chemical vapor deposition.

Author

Pirabul, Kritin, Zhao, Qi, Sunahiro, Shogo, Pan, Zheng-Ze, Yoshii, Takeharu, Hayasaka, Yuichiro, Hoi-Sing Pang, Eddie, Crespo-Otero, Rachel, Di Tommaso, Devis, Kyotani, Takashi, and Nishihara, Hirotomo

Subjects
CHEMICAL vapor deposition, GRAPHENE synthesis, NANOPOROUS materials, ELECTRIC capacity, SUSTAINABILITY, SUBSTRATES (Materials science)
Abstract

Template-assisted chemical vapor deposition (CVD) is a promising approach for fabricating nanoporous materials based on graphene walls. Among conventional metal oxide templates, CaO, produced through the thermal decomposition of CaCO3, offers improved environmental sustainability and lower production costs, thereby potentially making it a viable candidate for green template materials. Nevertheless, the underlying reaction mechanisms of the interaction on the CaO surface during the CVD process remain indeterminate, giving rise to challenges in regulating graphene formation and obtaining high-quality materials. In this work, a comprehensive experimental–theoretical investigation has unveiled the CVD mechanism on CaO. CaO exhibits efficient catalytic activity in the dissociation of CH4, thereby facilitating a thermodynamically favorable conversion of CH4 to graphene. These findings highlight the potential of using CaO as a substrate for graphene growth, combining both sustainability and cost-effectiveness. When the shell-like graphene layer deposited on CaO particles is released through the dissolution of CaO with HCl, the resulting nanoporous graphene-based materials can be readily compacted by the capillary force of the liquid upon drying. The folded surfaces, however, can become available for electric double-layer capacitance via electrochemical exfoliation under a low applied potential (<1.2 V vs. Ag/AgClO4). [ABSTRACT FROM AUTHOR]

Published
2024
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26. Prominent Structural Dependence of Quantum Capacitance Unraveled by Nitrogen‐Doped Graphene Mesosponge

Author

Tang, Rui, primary, Aziz, Alex, additional, Yu, Wei, additional, Pan, Zheng‐Ze, additional, Nishikawa, Ginga, additional, Yoshii, Takeharu, additional, Nomura, Keita, additional, Taylor, Erin E., additional, Stadie, Nicholas P., additional, Inoue, Kazutoshi, additional, Kotani, Motoko, additional, Kyotani, Takashi, additional, and Nishihara, Hirotomo, additional

Published
2023
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30. Hierarchically Porous and Minimally Stacked Graphene Cathodes for High‐Performance Lithium–Oxygen Batteries.

Author

Yu, Wei, Shen, Zhaohan, Yoshii, Takeharu, Iwamura, Shinichiroh, Ono, Manai, Matsuda, Shoichi, Aoki, Makoto, Kondo, Toshihiro, Mukai, Shin R., Nakanishi, Shuji, and Nishihara, Hirotomo

Subjects
LITHIUM-air batteries, CATHODES, GRAPHENE, ENERGY density, ELECTROCHEMICAL electrodes, ELECTROLYTES, GRAPHENE oxide
Abstract

Although lithium–oxygen batteries have attracted attention due to their extremely high energy densities, rational design, and critical evaluation of high‐energy‐density cathode for practical Li–O2 batteries is still urgently needed. Herein, the multiscale, angstrom‐to‐millimeter, precisely controllable synthesis of binder‐free cathodes with minimally stacked graphene free from edge sites is demonstrated. The proposed Li–O2 battery, based on a hierarchically porous cathode with a practical mass loading of >4.0 mg cm−2, simultaneously exhibits an unprecedented specific areal (>30.0 mAh cm−2), mass (>6300 mAh g−1), and volumetric (>480 mAh cm−3) capacities. The battery displays the optimal energy density of 793 Wh kg−1 critically normalized to the total mass of all active materials including electrolytes and even discharge products Li2O2. Comprehensive in situ characterizations demonstrate a unique discharge mechanism in hierarchical pores which contributes to competitive battery performance. Superior rate performance in a current density range of 0.1 to 0.8 mA cm−2 and long‐cycle stability (>260 cycles) at a current density of 0.4 mA cm−2, outperforming state‐of‐the‐art carbon cathodes. This study yields insight into next‐generation carbon cathodes, not only for use in practical Li–O2 batteries, but also in other metal–gas batteries with high energy densities. [ABSTRACT FROM AUTHOR]

Published
2024
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31. Edge‐Site‐Free and Topological‐Defect‐Rich Carbon Cathode for High‐Performance Lithium‐Oxygen Batteries

Author

Yu, Wei, primary, Yoshii, Takeharu, additional, Aziz, Alex, additional, Tang, Rui, additional, Pan, Zheng‐Ze, additional, Inoue, Kazutoshi, additional, Kotani, Motoko, additional, Tanaka, Hideki, additional, Scholtzová, Eva, additional, Tunega, Daniel, additional, Nishina, Yuta, additional, Nishioka, Kiho, additional, Nakanishi, Shuji, additional, Zhou, Yi, additional, Terasaki, Osamu, additional, and Nishihara, Hirotomo, additional

Published
2023
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36. Chemistry of zipping reactions in mesoporous carbon consisting of minimally stacked graphene layers

Author

Xia, Tian, primary, Yoshii, Takeharu, additional, Nomura, Keita, additional, Wakabayashi, Keigo, additional, Pan, Zheng-Ze, additional, Ishii, Takafumi, additional, Tanaka, Hideki, additional, Mashio, Takashi, additional, Miyawaki, Jin, additional, Otomo, Toshiya, additional, Ikeda, Kazutaka, additional, Sato, Yohei, additional, Terauchi, Masami, additional, Kyotani, Takashi, additional, and Nishihara, Hirotomo, additional

Published
2023
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40. Helically aligned fused carbon hollow nanospheres with chiral discrimination ability

Author

Maruyama, Jun, primary, Maruyama, Shohei, additional, Kashiwagi, Yukiyasu, additional, Watanabe, Mitsuru, additional, Shinagawa, Tsutomu, additional, Nagaoka, Toru, additional, Tamai, Toshiyuki, additional, Ryu, Naoya, additional, Matsuo, Koichi, additional, Ohwada, Mao, additional, Chida, Koki, additional, Yoshii, Takeharu, additional, Nishihara, Hirotomo, additional, Tani, Fumito, additional, and Uyama, Hiroshi, additional

Published
2022
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42. Structural Engineering of Nanocarbons Comprising Graphene Frameworks viaHigh-Temperature Annealing

Author

Pirabul, Kritin, Pan, Zheng-Ze, Tang, Rui, Sunahiro, Shogo, Liu, Hongyu, Kanamaru, Kazuya, Yoshii, Takeharu, and Nishihara, Hirotomo

Abstract

High-temperature annealing is an effective way to heal the defects of graphene-based nanocarbons and enhance their crystallinity. However, the thermally induced vibration of the graphene building blocks often leads to unfavorable micro-, nano-structural evolution including layer stacking. Herein, the key structural factors to achieve highly crystalline graphene frameworks with desired microstructures upon annealing at 1800 °C is revealed. The structural changes of fullerenes, single-walled carbon nanotubes, and graphene-based porous frameworks are precisely analyzed by their structural parameters, such as the total number of graphene edge sites and precise graphene stacking structures, using a novel advanced vacuum temperature-programmed desorption technique up to 1800 °C. The stacked structure is differentiated into loose and tightly stacking, where the loosely stacked structure is found to induce further stacking at high-temperature. Moreover, a graphene framework with an inner space size of greater than 4–7 nm is beneficial to avoid structural change upon high-temperature annealing. These findings offer both a fundamental understanding of the solid-state chemistry of nanocarbons under high temperatures and a viable strategy for engineering edge-site free graphene frameworks with pre-designed microstructures.The structural retention degree (SRD) is established as a numerical descriptor for the thermal stability of carbon materials. The loosely stacked structure and high surface curvature (represented by inner space size <4–7 nm) are responsible for diminished SRD of nanocarbons, as they are able to trigger the stacking of basal plane during high-temperature annealing.

Published
2023
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44. Synthesis of graphene mesosponge via catalytic methane decomposition on magnesium oxide

Author

Sunahiro, Shogo, primary, Nomura, Keita, additional, Goto, Shunsuke, additional, Kanamaru, Kazuya, additional, Tang, Rui, additional, Yamamoto, Masanori, additional, Yoshii, Takeharu, additional, N. Kondo, Junko, additional, Zhao, Qi, additional, Ghulam Nabi, Azeem, additional, Crespo-Otero, Rachel, additional, Di Tommaso, Devis, additional, Kyotani, Takashi, additional, and Nishihara, Hirotomo, additional

Published
2021
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45. Force-responsive ordered carbonaceous frameworks synthesized from Ni-porphyrin

Author

Chida, Koki, primary, Yoshii, Takeharu, additional, Takahashi, Kazuma, additional, Yamamoto, Masanori, additional, Kanamaru, Kazuya, additional, Ohwada, Mao, additional, Deerattrakul, Varisara, additional, Maruyama, Jun, additional, Kamiya, Kazuhide, additional, Hayasaka, Yuichiro, additional, Inoue, Masataka, additional, Tani, Fumito, additional, and Nishihara, Hirotomo, additional

Published
2021
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