Reactions of Graphene Nano-Flakes in Materials Chemistry and Astrophysics

Tachikawa, Hiroto; Iyama, Tetsuji

doi:10.3390/physchem2020011

Cited by 6 publications

(6 citation statements)

References 36 publications

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“…The binding energies in GNF-K + were lower than those of GNF-Li + and GNF-Na + . However, the values were always higher in energy than 1.0 kcal/mol, which was also higher than the binding energy of H2 to GNF without K. These features indicate that GNF-K + is also possible as a H2 storage [40].…”

Section: Comparison Of Binding Energies In Gnf-m-h2 (M = LI Na and K)mentioning

confidence: 85%

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Hydrogen Storages Based on Graphene Nano-Flakes: Density Functional Theory Approach

Tachikawa

2022

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Carbon materials such as graphene, carbon nanotubes, fullerene, and graphene nanoflakes (GNFs) are used for hydrogen storage. The doping of alkali metals to these materials generally increases the accumulation density of molecular hydrogen (H2). However, the reason why the doping enhances the ability of the H2 storage of GNF is not clearly known, although there are some explanations. In addition, the information on the storage capacity of GNF is ambiguous. In the present review article, we introduce our recent theoretical studies on the interaction of GNF with H2 molecules carried out to elucidate the mechanism of hydrogen storage in alkali-doped GNFs. As alkali metals, lithium (Li), sodium (Na), and potassium (K) were examined, and the abilities of hydrogen storage were discussed. Next, the mechanism of Li-diffusion on GNF, which plays a crucial role in Li-battery, was presented. There are several unanswered questions. In particular, does lithium diffuse randomly on GNF? Or is there a specific diffusion path? We present our study, which elucidates the factors governing lithium diffusion on GNF. If the dominant factor is known, it is possible to arbitrarily control the diffusion path of lithium. This will lead to the development of highly functional battery materials. Finally, the molecular design of H adsorption–desorption reversible storage devices based on GNF will be introduced. Elucidating the mechanism of hydrogen storage, Li-diffusion on GNF, and molecular design of storage device is important in understanding the current molecular devices and provide a deeper insight into materials chemistry.

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Section: Comparison Of Binding Energies In Gnf-m-h2 (M = LI Na and K)mentioning

confidence: 85%

“…For comparison, the hydrogen adsorption capacity of K + was examined [40]. The binding energy of H2 to GNF-K + is plotted in Figure 7.…”

Section: Comparison Of Binding Energies In Gnf-m-h2 (M = LI Na and K)mentioning

confidence: 99%

Hydrogen Storages Based on Graphene Nano-Flakes: Density Functional Theory Approach

Tachikawa

2022

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“…Previous studies have shown that these levels of theory produce reasonable electronic structures of the carbon systems. [26][27][28][29][30][31] The electronic states of C 60 -PCBM were obtained by natural population analysis and natural bond orbital methods at the CAM-B3LYP/6-31 G(d) level. The binding energy of PCBM to C 60 and E bind are defined as follows:…”

Section: Methods Of Calculationmentioning

confidence: 99%

Density functional theory study on the interaction of C₆₀ fullerene with PCBM

Abe,

Tachikawa,

Iyama

et al. 2023

Jpn. J. Appl. Phys.

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Functionalized fullerenes are known as high-performance molecules. Herein, the interaction of C60 fullerene with Phenyl-C61-butyric-acid-methyl-ester (PCBM) is investigated by means of density functional theory (DFT) method to elucidate the structures and electronic states of C60-PCMB complexes. C60-PCBM blends are typically used in solar cell. Studying the electronic structure of C60-PCBM is important for elucidating the mechanism of solar cells. The intermolecular distances for C60 and PCBM dimers were calculated to be 3.70 and 2.34 Å, respectively. In C60 dimer, the five membered ring of C60 interacted with the six membered ring of neighbour C60. Two hydrogen bonds between side chains of PCBM are connected in the PCBM dimer. The binding energies were 1.4 kcal/mol (C60 dimer) and 2.6 kcal/mol (PCBM dimer). In the C60-PCBM complex, five different structures were found to be stable. The binding energies were distributed in the range 1.6-3.7 kcal/mol. The electronic states and excitation energies of C60-PCBM complexes and the basis set superposition error (BSSE) were discussed on theoretical results.

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“…Additional calculations were carried out at the same level of theory for Al + , Al 2+ , and Al 3+ systems. We previously investigated interactions between graphene and various molecules using DFT at the same level of theory [ 27 , 28 , 29 , 30 , 31 ]. A similar technique was used for the GR-Al-(H 2 ) n system in this study.…”

Section: Methods Of Calculationmentioning

confidence: 99%

Aluminum-Doping Effects on the Electronic States of Graphene Nanoflake: Diffusion and Hydrogen Storage Mechanism

et al. 2023

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Graphene nanoflakes are widely utilized as high-performance molecular devices due to their chemical stability and light weight. In the present study, the interaction of aluminum species with graphene nanoflake (denoted as GR-Al) has been investigated using the density functional theory (DFT) method to elucidate the doping effects of Al metal on the electronic states of GR. The mechanisms of the diffusion of Al on GR surface and the hydrogen storage of GR-Al were also investigated in detail. The neutral, mono-, di-, and trivalent Al ions (expressed as Al, Al+, Al2+, and Al3+, respectively) were examined as the Al species. The DFT calculations showed that the charge transfer interaction between Al and GR plays an important role in the binding of Al species to GR. The diffusion path of Al on GR surface was determined: the barrier heights of Al diffusion were calculated to be 2.1–2.8 kcal mol−1, which are lower than Li+ on GR (7.2 kcal/mol). The possibility of using GR-Al for hydrogen storage was also discussed on the basis of the theoretical results.

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Reactions of Graphene Nano-Flakes in Materials Chemistry and Astrophysics

Cited by 6 publications

References 36 publications

Hydrogen Storages Based on Graphene Nano-Flakes: Density Functional Theory Approach

Hydrogen Storages Based on Graphene Nano-Flakes: Density Functional Theory Approach

Density functional theory study on the interaction of C₆₀ fullerene with PCBM

Aluminum-Doping Effects on the Electronic States of Graphene Nanoflake: Diffusion and Hydrogen Storage Mechanism

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Reactions of Graphene Nano-Flakes in Materials Chemistry and Astrophysics

Cited by 6 publications

References 36 publications

Hydrogen Storages Based on Graphene Nano-Flakes: Density Functional Theory Approach

Hydrogen Storages Based on Graphene Nano-Flakes: Density Functional Theory Approach

Density functional theory study on the interaction of C60 fullerene with PCBM

Aluminum-Doping Effects on the Electronic States of Graphene Nanoflake: Diffusion and Hydrogen Storage Mechanism

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Density functional theory study on the interaction of C₆₀ fullerene with PCBM