Reversible Loss of Bernal Stacking during the Deformation of Few-Layer Graphene in Nanocomposites

Nanometer-thick and crystalline sp3-bonded carbon sheets are promising new wide band-gap semiconducting materials for electronics, photonics, and medical devices. Diamane was prepared from the exposure of bi-layer graphene to hydrogen radicals produced by the hot-filament process at low pressure and temperature. A sharp sp3-bonded carbon stretching mode was observed in ultraviolet Raman spectra at around 1344–1367 cm−1 while no sp2-bonded carbon peak was simultaneously detected. By replacing bi-layer graphene with few-layer graphene, diamanoid/graphene hybrids were formed from the partial conversion of few-layer graphene, due to the prevalent Bernal stacking sequence. Raman spectroscopy, electron diffraction, and Density Functional Theory calculations show that partial conversion generates twisted bi-layer graphene located at the interface between the upper diamanoid domain and the non-converted graphenic domain underneath. Carbon-hydrogen bonding in the basal plane of hydrogenated few-layer graphene, where carbon is bonded to a single hydrogen over an area of 150 μm2, was directly evidenced by Fourier transform infrared microscopy and the actual full hydrogenation of diamane was supported by first-principle calculations. Those results open the door to large-scale production of diamane, diamanoids, and diamanoid/graphene hybrids.

Download Full-text

Modern methods of obtaining few-layer graphene structures by the method of electrochemical exfoliation of graphite

Perspektivnye Materialy ◽

10.30791/1028-978x-2018-7-5-15 ◽

2018 ◽

pp. 5-15

Author(s):

E. S. Bakunin ◽

◽

E. Yu. Obraztsova ◽

A. V. Rukhov ◽

◽

...

Keyword(s):

Electrochemical Exfoliation ◽

Layer Graphene ◽

Modern Methods ◽

Few Layer Graphene ◽

Graphene Structures

Download Full-text

Omnidirectional terahertz photonic band gap broaden effect in one-dimensional photonic crystal containing few-layer graphene

Optics Communications ◽

10.1016/j.optcom.2021.126898 ◽

2021 ◽

Vol 490 ◽

pp. 126898

Author(s):

Feng Wu ◽

Mingyuan Chen ◽

Zhanxu Chen ◽

Chengping Yin

Keyword(s):

Photonic Crystal ◽

Band Gap ◽

Photonic Band Gap ◽

One Dimensional ◽

Dimensional Photonic Crystal ◽

Layer Graphene ◽

Few Layer Graphene ◽

Photonic Band

Download Full-text

Properties of Silicone Rubber-Based Composites Reinforced with Few-Layer Graphene and Iron Oxide or Titanium Dioxide

Polymers ◽

10.3390/polym13101550 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1550

Author(s):

Vineet Kumar ◽

Anuj Kumar ◽

Minseok Song ◽

Dong-Joo Lee ◽

Sung-Soo Han ◽

...

Keyword(s):

Magnetic Properties ◽

Titanium Dioxide ◽

Iron Oxide ◽

Stress Relaxation ◽

Silicone Rubber ◽

Room Temperature ◽

Relaxation Rates ◽

Layer Graphene ◽

Few Layer Graphene ◽

Mechanical Actuation

The increasing demand for polymer composites with novel or improved properties requires novel fillers. To meet the challenges posed, nanofillers such as graphene, carbon nanotubes, and titanium dioxide (TiO2) have been used. In the present work, few-layer graphene (FLG) and iron oxide (Fe3O4) or TiO2 were used as fillers in a room-temperature-vulcanized (RTV) silicone rubber (SR) matrix. Composites were prepared by mixing RTV-SR with nanofillers and then kept for vulcanization at room temperature for 24 h. The RTV-SR composites obtained were characterized with respect to their mechanical, actuation, and magnetic properties. Fourier-transform infrared spectroscopy (FTIR) analysis was performed to investigate the composite raw materials and finished composites, and X-ray photoelectron spectroscopy (XPS) analysis was used to study composite surface elemental compositions. Results showed that mechanical properties were improved by adding fillers, and actuation displacements were dependent on the type of nanofiller used and the applied voltage. Magnetic stress-relaxation also increased with filler amount and stress-relaxation rates decreased when a magnetic field was applied parallel to the deformation axes. Thus, this study showed that the inclusion of iron oxide (Fe3O4) or TiO2 fillers in RTV-SR improves mechanical, actuation, and magnetic properties.

Download Full-text

Temperature Dependence of G and D’ Phonons in Monolayer to Few-Layer Graphene with Vacancies

Nanoscale Research Letters ◽

10.1186/s11671-020-03414-w ◽

2020 ◽

Vol 15 (1) ◽

Author(s):

Mingming Yang ◽

Longlong Wang ◽

Xiaofen Qiao ◽

Yi Liu ◽

Yufan Liu ◽

...

Keyword(s):

Negative Temperature Coefficient ◽

Negative Temperature ◽

Intrinsic Properties ◽

Temperature Dependent ◽

Phonon Interaction ◽

Electron Phonon Interaction ◽

Layer Graphene ◽

A Value ◽

Few Layer Graphene

Abstract The defects into the hexagonal network of a sp2-hybridized carbon atom have been demonstrated to have a significant influence on intrinsic properties of graphene systems. In this paper, we presented a study of temperature-dependent Raman spectra of G peak and D’ band at low temperatures from 78 to 318 K in defective monolayer to few-layer graphene induced by ion C+ bombardment under the determination of vacancy uniformity. Defects lead to the increase of the negative temperature coefficient of G peak, with a value almost identical to that of D’ band. However, the variation of frequency and linewidth of G peak with layer number is contrary to D’ band. It derives from the related electron-phonon interaction in G and D’ phonon in the disorder-induced Raman scattering process. Our results are helpful to understand the mechanism of temperature-dependent phonons in graphene-based materials and provide valuable information on thermal properties of defects for the application of graphene-based devices.

Download Full-text