Morphed graphene nanostructures: Experimental evidence for existence

Calderón, H.A.; Estrada-Guel, I.; Alvarez-Ramírez, Fernando; Hadjiev, V. G.; Hernandez, Francisco C. Robles

doi:10.1016/j.carbon.2016.02.056

Cited by 39 publications

(34 citation statements)

References 24 publications

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“…Electronic band structure calculations reveal that it is an insulator with a direct band gap of 4.45 eV. Its simulated XRD patterns match well with the measured XRD data of a recently reported unidentified carbon phase found in milled fullerene soot [41]. These findings establish a computational discovery of a new rhombohedral diamond, which expands our understanding of the prominent class of diamondlike materials.…”

Section: Discussionsupporting

confidence: 77%

“…Electronic band calculations reveal that it is an insulator with a direct band gap of 4.45 eV. The stimulated x-ray diffraction spectrum provides an excellent match to distinct diffraction peaks found in the milled fullerene soot [41]. These findings lay a foundation for further exploration of this new diamond phase.…”

Section: Introductionmentioning

confidence: 64%

“…To further characterize R16 carbon and make a connection to its experimental synthesis, we have simulated its x-ray diffraction (XRD) spectra as well as those for graphite, diamond, BC8, and BC12 carbon and compared the results with recent experimental XRD data of morphed graphene nanostructures obtained from milled fullerene soot [41]. Results in Fig.…”

Section: Structurementioning

confidence: 99%

“…3 show that the XRD of R16 carbon produces a more complicated pattern than those of similarly bonded diamond, BC8, and BC12, reflecting its structural complexity stemming from its multiple bond lengths and angles as discussed above. The experimental XRD diffraction data contain peaks arising from unreacted and amorphized graphite and other unidentified carbon phases [41]. The broad peak on the lower-angle side is attributed to the dominant crystalline graphite (002) diffraction around 26 • and the contribution from the amorphized graphite structure.…”

Section: Structurementioning

confidence: 99%

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Computational discovery of a new rhombohedral diamond phase

Wang

Mizuseki

et al. 2018

Phys. Rev. B

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We identify by first-principles calculations a new diamond phase in R3c (D 6 3d) symmetry, which has a 16-atom rhombohedral primitive cell, thus termed R16 carbon. This rhombohedral diamond comprises a characteristic all-sp 3 six-membered-ring bonding network, and it is energetically more stable than previously identified diamondlike six-membered-ring bonded BC8 and BC12 carbon phases. A phonon mode analysis verifies the dynamic structural stability of R16 carbon, and electronic band calculations reveal that it is an insulator with a direct band gap of 4.45 eV. Simulated x-ray diffraction patterns provide an excellent match to recently reported distinct diffraction peaks found in milled fullerene soot, suggesting a viable experimental synthesis route. These findings pave the way for further exploration of this new diamond phase and its outstanding properties.

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Section: Discussionsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 64%

Section: Structurementioning

confidence: 99%

Section: Structurementioning

confidence: 99%

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Computational discovery of a new rhombohedral diamond phase

Wang

Mizuseki

et al. 2018

Phys. Rev. B

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“…The characteristics of the morphed graphenes have been previously predicted numerically [28] and more recently we have proposed their existence [29]. However, there is still a great discrepancy regarding the morphed graphenes (Rh6 and Rh6-II).…”

Section: Introductionmentioning

confidence: 78%

HRTEM low dose: the unfold of the morphed graphene, from amorphous carbon to morphed graphenes

Calderón¹,

Okonkwo

Estrada‐Guel

et al. 2016

Adv Struct Chem Imag

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We present experimental evidence under low-dose conditions transmission electron microscopy for the unfolding of the evolving changes in carbon soot during mechanical milling. The milled soot shows evolving changes as a function of the milling severity or time. Those changes are responsible for the transformation from amorphous carbon to graphenes, graphitic carbon, and highly ordered structures such as morphed graphenes, namely Rh6 and Rh6-II. The morphed graphenes are corrugated layers of carbon with cross-linked covalently nature and sp2- or sp3-type allotropes. Electron microscopy and numerical simulations are excellent complementary tools to identify those phases. Furthermore, the TEAM 05 microscope is an outstanding tool to resolve the microstructure and prevent any damage to the sample. Other characterization techniques such as XRD, Raman, and XPS fade to convey a true identification of those phases because the samples are usually blends or mixes of the mentioned phases.

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Plasma‐Based Synthesis of Freestanding Graphene from a Natural Resource for Sensing Application

Zafar

Liu

Hernández

et al. 2023

Adv Materials Inter

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The bottomup approach, that is, modified Hummers' method, is a well-established chemical synthesis technique to synthesize graphene. However, this technique, not only utilizes strong acids and oxidants [4,5] but also entails numerous steps of synthesis such as dilution, mixing, oxidation, reduction, washing, centrifuging, and intense stirring. [6] On the other hand, some of the bottom-up methods, in particular, chemical vapor deposition (CVD) and plasma-enhanced chemical vapor deposition (PE-CVD) are expensive and laborious methodologies comprising pre-synthesis and post-synthesis requirements, that is, high vacuum, pre-heating, and subsequent transfer of graphene to other substrates. [7][8][9] Recently, a new bottom-up approach, so-called atmospheric pressure microwave plasma (APMP) is gaining popularity as it synthesizes graphene without the hassles of pre-heating, high vacuuming, and the need for a substrate. Most importantly, the graphene obtained through this method happens to be freestanding and scalable. [10,11] The precursors used for producing graphene have a significant role in determining the sustainability of the synthesis process. Often graphene is produced from commercially available graphite, [12] graphene oxide (GO), [13] methane, or other unreplenishable hydrocarbons. [14] These resources Atmospheric pressure microwave plasma has the lead in synthesizing freestanding and scalable graphene within seconds without the need for high vacuum and temperature. However, the process is limited in utilizing chemical sources for synthesis, such as methane and ethanol. Herein, the usage of an extract of a sustainable precursor, that is, Melaleuca alternifolia, commonly known as tea tree, is for the first time reported to synthesize graphene nanosheets in atmospheric pressure microwave plasma. The synthesis is carried out in a single step at a remarkably low microwave power of 200 W. The morphology, structure, and electrochemical properties of graphene are studied using state-of-the-art characterization techniques such as Raman spectroscopy, X-ray diffraction, transmission electron microscopy (TEM) and electrochemical impedance spectroscopy. The TEM images reveal the presence of a combination of nanostructures such as nano-horns, nano-rods, or nano-onions consisting of multi-layer graphitic architectures. An excellent sensing capability of as-synthesized graphene is demonstrated through the detection of diuron herbicide. A commendable linear range of 20 µm to 1 mm and a limit of detection of 5 µm of diuron is recorded.

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Morphed graphene nanostructures: Experimental evidence for existence

Cited by 39 publications

References 24 publications

Computational discovery of a new rhombohedral diamond phase

Computational discovery of a new rhombohedral diamond phase

HRTEM low dose: the unfold of the morphed graphene, from amorphous carbon to morphed graphenes

Plasma‐Based Synthesis of Freestanding Graphene from a Natural Resource for Sensing Application

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