Distinguishing Zigzag and Armchair Edges on Graphene Nanoribbons by X-ray Photoelectron and Raman Spectroscopies

Kim, Jungpil; Lee, Nodo; Min, Young Hwan; Noh, Seokhwan; Kim, Nam-Koo; Jung, Sung-Jin; Joo, Minho; Yamada, Yoshio

doi:10.1021/acsomega.8b02744

Cited by 76 publications

(48 citation statements)

References 43 publications

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“…Table 1 shows the calculated gap between HOMO and LUMO of the GNFs with or without heptagons. It has been reported that the HOMO–LUMO gap increases with decreasing the size of graphene 31 and introducing heptagons in graphene. 33 As shown in Table 1 , the HOMO–LUMO gap of the GNF with zero heptagons was 0.80 eV, which decreased to 0.23 eV when four isolated heptagons were introduced, as the size of GNF and the number of isolated heptagons increased.…”

Section: Resultsmentioning

confidence: 99%

“…The binding energy associated with the C1 region was higher than that associated with the C2 region because the terminal hydrogen atoms donate electrons to the carbon atoms (C2). 16 , 28 , 29 , 31 The binding energy associated with the C3 region (indicated by two isolated heptagons in the GNF structure) was 284.7 eV (yellow line in Figure 3 b), which was the highest binding energy among the C1, C2, and C3 regions owing to the electron-donating nature of the heptagons ( Figure S1 ). All the structures used in this study showed the same tendency ( Table 2 and Figure 3 ).…”

Section: Resultsmentioning

confidence: 99%

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Heptagons in the Basal Plane of Graphene Nanoflakes Analyzed by Simulated X-ray Photoelectron Spectroscopy

2021

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The performance of graphene-based electronic devices depends critically on the existence of topological defects such as heptagons. Identifying heptagons at the atomic scale is important to completely understand the electronic properties of these materials. In this study, we report an atomic-scale analysis of graphene nanoflakes with two to eight isolated or connected heptagons, using simulated C 1s X-ray photoelectron spectroscopy (XPS) to estimate the XPS profiles depending on the density and the position of the heptagons. The introduction of up to 24% of isolated heptagons shifted the peak position toward high binding energies (284.0 to 284.3 eV), whereas the introduction of up to 39% of connected heptagons shifted the calculated peak position toward low binding energies (284.0 to 283.5 eV). The presence of heptagons also influenced the full width at half-maximum (FWHM). The introduction of 24% of isolated heptagons increased the FWHMs from 1.25 to 1.50 eV. However, the introduction of connected heptagons did not increase the FWHMs above 1.40 eV. The FWHMs increased to 1.40 eV for 19% of connected heptagons, but did not increase further as the percentage of connected heptagons increased to 39%. Based on the calculated results, the XPS profiles of graphene nanoflakes containing heptagons with different densities and positions can be obtained. Our precise identification of heptagons in graphene nanoflakes by XPS lays the groundwork for the analysis of graphene.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Heptagons in the Basal Plane of Graphene Nanoflakes Analyzed by Simulated X-ray Photoelectron Spectroscopy

2021

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“…Recently, our group demonstrated the peak shifts and the corresponding full widths at half-maximum (fwhms) of the XPS peaks of nanocarbon materials with various defects. 39 , 41 − 43 The XPS peak originating from vacancy defects appears at ±0.7 eV from the C=C and/or C–H main peak. 39 , 41 Thus, the fwhm of the peak originating from the C=C and/or C–H peak increased upon the introduction of internal pores to the CNT wall due to the presence of an increased number of vacancies and edge structures in the wall.…”

Section: Resultsmentioning

confidence: 99%

“… 39 , 41 − 43 The XPS peak originating from vacancy defects appears at ±0.7 eV from the C=C and/or C–H main peak. 39 , 41 Thus, the fwhm of the peak originating from the C=C and/or C–H peak increased upon the introduction of internal pores to the CNT wall due to the presence of an increased number of vacancies and edge structures in the wall. 39 , 41 However, the fwhm of the peak originating from the C=C and/or C–H moiety of the HD-SWCNT film was not increased compared to that of the SWCNTs ( Figure 2 c), which indicates either that the number of internal pores was small or that no internal pores were introduced.…”

Section: Resultsmentioning

confidence: 99%

Water Adsorption Behavior on a Highly Dense Single-Walled Carbon Nanotube Film with an Enhanced Interstitial Space

Kim

Yang

et al. 2021

ACS Omega

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In this study, we describe the adsorption behavior of water (H 2 O) in the interstitial space of single-walled carbon nanotubes (SWCNTs). A highly dense SWCNT (HD-SWCNT) film with a remarkably enhanced interstitial space was fabricated through mild HNO 3 /H 2 SO 4 treatment. The N 2 , CO 2 , and H 2 adsorption isotherm results indicated remarkably developed micropore volumes (from 0.10 to 0.40 mL g –1 ) and narrower micropore widths (from 1.5 to 0.9 nm) following mild HNO 3 /H 2 SO 4 treatment, suggesting that the interstitial space was increased from the initial densely-packed network assembly structure of the SWCNTs. The H 2 O adsorption isotherm of the HD-SWCNT film at 303 K showed an increase in H 2 O adsorption (i.e., by ∼170%), which increased rapidly from the critical value of relative pressure (i.e., 0.3). Despite the remarkably enhanced adsorption capacity of H 2 O, the rates of H 2 O adsorption and desorption in the interstitial space did not change. This result shows an adsorption behavior different from that of the fast transport of H 2 O molecules in the internal space of the SWCNTs. In addition, the adsorption capacities of N 2 , CO 2 , H 2 , and H 2 O molecules in the interstitial space of the HD-SWCNT film showed a linear relationship with the kinetic diameter, indicating an adsorption behavior that is highly dependent on the kinetic diameter.

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“…The analysis of the graphene tension was carried out for two basic directions (if the edge is cut-out along bonds between carbon atoms, one receives the “armchair” edge, otherwise the cutting-out in the perpendicular direction has the edge called “zigzag” [49]).…”

Section: Assumptions For Modeling the Graphene Structurementioning

confidence: 99%

A New Approach of Mathematical Analysis of Structure of Graphene as a Potential Material for Composites

et al. 2019

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The new analysis of a simplified plane model of single-layered graphene is presented in this work as a potential material for reinforcement in ultralight and durable composites. However, owing to the clear literature discrepancies regarding the mechanical properties of graphene, it is extremely difficult to conduct any numerical analysis to design parts of machines and devices made of composites. Therefore, it is necessary to first systemize the analytical and finite element method (FEM) calculations, which will synergize mathematical models, used in the analysis of mechanical properties of graphene sheets, with the very nature of the chemical bond. For this reason, the considered model is a hexagonal mesh simulating the bonds between carbon atoms in graphene. The determination of mechanical properties of graphene was solved using the superposition method and finite element method. The calculation of the graphene tension was performed for two main directions of the graphene arrangement: armchair and zigzag. The computed results were verified and referred to articles and papers in the accessible literature. It was stated that in unloaded flake of graphene, the equilibrium of forces exists; however, owing to changes of inter-atom distance, the inner forces occur, which are responsible for the appearance of strains.

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Distinguishing Zigzag and Armchair Edges on Graphene Nanoribbons by X-ray Photoelectron and Raman Spectroscopies

Cited by 76 publications

References 43 publications

Heptagons in the Basal Plane of Graphene Nanoflakes Analyzed by Simulated X-ray Photoelectron Spectroscopy

Heptagons in the Basal Plane of Graphene Nanoflakes Analyzed by Simulated X-ray Photoelectron Spectroscopy

Water Adsorption Behavior on a Highly Dense Single-Walled Carbon Nanotube Film with an Enhanced Interstitial Space

A New Approach of Mathematical Analysis of Structure of Graphene as a Potential Material for Composites

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