scholarly journals A Facile and Scalable Approach in the Fabrication of Tailored 3D Graphene Foam via Freeze Drying

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 864
Author(s):  
Tony Thomas ◽  
Arvind Agarwal
Keyword(s):  
Thermal Diffusivity ◽  
Boron Nitride ◽  
Freeze Drying ◽  
High Energy ◽  
Boron Nitride Nanotubes ◽  
Solid Loading ◽  
Small Scale ◽  
Graphene Foam ◽  
3D Graphene ◽  
The Matrix

One of the challenges in the processing of advanced composite materials with 2D reinforcement is their extensive agglomeration in the matrix. 3D architecture of 2D graphene sheets into a Graphene Foam (GrF) assembly has emerged as an effective way to overcome agglomeration. The highly reticulated network of branches and nodes of GrF offers a seamless pathway for photon and electron conduction in the matrix along with improved mechanical properties. 3D GrF nano-filler is often fabricated by chemical vapor deposition (CVD) technique, which demands high energy, slow deposition rate, and restricting production to small scale. This work highlights freeze-drying (FD) technique to produce 3D graphene nanoplatelets (GNP) foam with a similar hierarchical structure to the CVD GrF. The FD technique using water as the main chemical in 3D GNP foam production is an added advantage. The flexibility of the FD in producing GNP foams of various pore size and morphology is elucidated. The simplicity with which one can engineer thermodynamic conditions to tailor the pore shape and morphology is presented here by altering the GNP solid loading and mold geometry. The FD 3D GNP foam is mechanically superior to CVD GrF as it exhibited 1280 times higher elastic modulus. However, thermal diffusivity of the FD GNP foam is almost 0.5 times the thermal diffusivity of the CVD GrF due to the defects in GNP particles and pore architecture. The versatility in GNP foam scalability and compatibility to form foam of other 1D and 2D material systems (e.g., carbon nanotubes, boron nitride nanotubes, and boron nitride nanoplatelets) brings a unique dimensionality to FD as an advanced engineering foam development process.

Organic solvent-assisted free-standing Li2MnO3·LiNi1/3Co1/3Mn1/3O2 on 3D graphene as a high energy density cathode

2015 ◽  
Vol 51 (91) ◽  
pp. 16381-16384 ◽  
Author(s):  
Yuelong Xin ◽  
Liya Qi ◽  
Yiwei Zhang ◽  
Zicheng Zuo ◽  
Henghui Zhou ◽  
...  
Keyword(s):  
Energy Density ◽  
Organic Solvent ◽  
Freeze Drying ◽  
Large Scale ◽  
High Energy ◽  
High Energy Density ◽  
Free Standing ◽  
3D Graphene ◽  
Active Particles

A novel organic solvent-assisted freeze-drying pathway, which can effectively protect and uniformly distribute active particles, is developed to fabricate a free-standing Li2MnO3·LiNi1/3Co1/3Mn1/3O2 (LR)/rGO electrode on a large scale.

scholarly journals Phonon Localization in Boron Nitride Nanotubes: Mixing Effect of 10B Isotopes and Vacancies

2021 ◽  
Author(s):  
Md. Sherajul Islam ◽  
Ashraful Hossain Howlader ◽  
Rongkun Zheng ◽  
Catherine Stampfl ◽  
Jeongwon Park ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Localization Length ◽  
Low Frequency ◽  
Blue Shift ◽  
High Energy ◽  
Boron Nitride Nanotubes ◽  
Forced Oscillation Technique ◽  
Phonon Modes ◽  
Mixing Effect ◽  
Phonon Localization

Abstract We explored the mixing effect of 10B isotopes and boron (B) or nitrogen (N) vacancies on the atomic vibrational properties of (10, 0) single-wall boron nitride nanotubes (BNNT). The forced oscillation technique was employed to evaluate the phonon modes for the entire range (0-100%) of 10B isotopes and atomic vacancy densities ranging from 0 to 30%. With increasing isotope densities, we noticed a blue-shift of the Raman active A1 phonon peak, whereas an increased density of mixed or independent B and N vacancies resulted in the emergence of a new low-frequency peak and the annihilation of the A1 peak in the phonon density-of-states. High-energy optical phonons were localized as a result of both 10B isotopes and the presence of mixing defects. We generated typical mode patterns for different defects to show the phonon localization processes due to the defects. We found an asymmetrical nature of the localization length with increasing 10B isotope content, which corresponds well with the isotope inherited localization length of carbon nanotubes and mono-layer graphene. The localization length falls abruptly with the increase in concentration of both atomic vacancies (B or N) and mixing defects (10B isotope and vacancies). These findings are critical for understanding heat conduction and nanoscopic vibrational investigations like tip-enhanced Raman spectra in BNNT, which can map local phonon energies.

scholarly journals Fabrication and Mechanical Properties of Boron Nitride Nanotube Reinforced Boron Carbide Ceramics

2020 ◽  
Author(s):  
Bingsai Liu ◽  
Yuanping Gu ◽  
Yuchun Ji ◽  
Guoyuan Zheng ◽  
Feiwen Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Particle Size ◽  
Boron Nitride ◽  
Boron Carbide ◽  
Sintering Temperature ◽  
Composite Ceramic ◽  
Boron Nitride Nanotubes ◽  
The Matrix ◽  
Carbide Ceramics

Abstract A series of BNNTs/B4C composite ceramic were prepared by the spark plasma sintering (SPS) technology using boron carbide (B4C) powders as the matrix and boron nitride nanotubes (BNNTs) as the toughening phase. The XRD, SEM, TEM and HR-TEM were used to characterize the B4C samples. The influence of sintering temperature, BNNTs content and matrix particle size on the microstructures and mechanical properties of B4C composite ceramics, as well the toughening mechanism were investigated in detail. The experimental results showed that changing the particle size of the powder, increasing the sintering temperature and adding BNNTs could significantly improve the mechanical properties of the material. The ceramic samples obtained by adding 5wt.% BNNTs content sintered at 1750℃ displayed the best mechanical properties. Its relative density, microhardness and fracture toughness respectively were 99.41%, 32.68 GPa and 6.87 Mpa·m1/2, respectively. In particular, the fracture toughness value of the BNNTs/B4C composite ceramic was 54.59% higher than that of B4C ceramics without BNNTs.

Molecular insights on the dynamic stability of peptide nucleic acid functionalized carbon and boron nitride nanotubes

2021 ◽  
Vol 23 (1) ◽  
pp. 219-228
Author(s):  
Nabanita Saikia ◽  
Mohamed Taha ◽  
Ravindra Pandey
Keyword(s):  
Nucleic Acid ◽  
Boron Nitride ◽  
Nucleic Acids ◽  
Dynamic Stability ◽  
Peptide Nucleic Acid ◽  
Rational Design ◽  
Peptide Nucleic Acids ◽  
Boron Nitride Nanotubes ◽  
Molecular Hybrids ◽  
Single Wall Nanotubes

The rational design of self-assembled nanobio-molecular hybrids of peptide nucleic acids with single-wall nanotubes rely on understanding how biomolecules recognize and mediate intermolecular interactions with the nanomaterial's surface.

Density Functional Theory Study of Antioxidant Adsorption onto Single- Wall Boron Nitride Nanotubes: Design of New Antioxidant Delivery Systems

2019 ◽  
Vol 22 (7) ◽  
pp. 470-482
Author(s):  
Samereh Ghazanfary ◽  
Fatemeh Oroojalian ◽  
Rezvan Yazdian-Robati ◽  
Mehdi Dadmehr ◽  
Amirhossein Sahebkar
Keyword(s):  
Density Functional Theory ◽  
Boron Nitride ◽  
Vitamin C ◽  
Electric Field ◽  
External Electric Field ◽  
Lipoic Acid ◽  
Density Functional ◽  
Cell Interaction ◽  
Boron Nitride Nanotubes ◽  
Functional Theory

Background: Boron Nitride Nanotubes (BNNTs) have recently emerged as an interesting field of study, because they could be used for the realization of developed, integrated and compact nanostructures to be formulated. BNNTs with similar surface morphology, alternating B and N atoms completely substitute for C atoms in a graphitic-like sheet with nearly no alterations in atomic spacing, with uniformity in dispersion in the solution, and readily applicable in biomedical applications with no obvious toxicity. Also demonstrating a good cell interaction and cell targeting. Aim and Objective: With a purpose of increasing the field of BNNT for drug delivery, a theoretical investigation of the interaction of Melatonin, Vitamin C, Glutathione and lipoic acid antioxidants using (9, 0) zigzag BNNTs is shown using density functional theory. Methods: The geometries corresponding to Melatonin, Vitamin C, Glutathione and lipoic acid and BNNT with different lengths were individually optimized with the DMOL3 program at the LDA/ DNP (fine) level of theory. Results: In the presence of external electric field Melatonin, Vitamin C, Glutathione and lipoic acid could be absorbed considerably on BNNT with lengths 22 and 29 Å, as the adsorption energy values in the presence of external electric field are considerably increased. Conclusion: The external electric field is an appropriate technique for adsorbing and storing antioxidants on BNNTs. Moreover, it is believed that applying the external electric field may be a proper method for controlling release rate of drugs.

scholarly journals About the possibility of creating a high-performance sensor based on boron nitride nanotubes

2020 ◽  
Author(s):  
N. P. Boroznina ◽  
M. A. Vdovin ◽  
I. V. Zaporotskova ◽  
S. V. Boroznin ◽  
P. A. Zaporotskov
Keyword(s):  
Boron Nitride ◽  
High Performance ◽  
Boron Nitride Nanotubes

scholarly journals Creation of Negatively Charged Boron Vacancies in Hexagonal Boron Nitride Crystal by Electron Irradiation and Mechanism of Inhomogeneous Broadening of Boron Vacancy-Related Spin Resonance Lines

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1373
Author(s):  
Fadis F. Murzakhanov ◽  
Boris V. Yavkin ◽  
Georgiy V. Mamin ◽  
Sergei B. Orlinskii ◽  
Ivan E. Mumdzhi ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Electron Irradiation ◽  
Near Infrared ◽  
Hexagonal Boron Nitride ◽  
Optical Excitation ◽  
High Energy ◽  
Infrared Range ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Spin Resonance

Optically addressable high-spin states (S ≥ 1) of defects in semiconductors are the basis for the development of solid-state quantum technologies. Recently, one such defect has been found in hexagonal boron nitride (hBN) and identified as a negatively charged boron vacancy (VB−). To explore and utilize the properties of this defect, one needs to design a robust way for its creation in an hBN crystal. We investigate the possibility of creating VB− centers in an hBN single crystal by means of irradiation with a high-energy (E = 2 MeV) electron flux. Optical excitation of the irradiated sample induces fluorescence in the near-infrared range together with the electron spin resonance (ESR) spectrum of the triplet centers with a zero-field splitting value of D = 3.6 GHz, manifesting an optically induced population inversion of the ground state spin sublevels. These observations are the signatures of the VB− centers and demonstrate that electron irradiation can be reliably used to create these centers in hBN. Exploration of the VB− spin resonance line shape allowed us to establish the source of the line broadening, which occurs due to the slight deviation in orientation of the two-dimensional B-N atomic plains being exactly parallel relative to each other. The results of the analysis of the broadening mechanism can be used for the crystalline quality control of the 2D materials, using the VB− spin embedded in the hBN as a probe.

scholarly journals Four-dimensional vibrational spectroscopy for nanoscale mapping of phonon dispersion in BN nanotubes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ruishi Qi ◽  
Ning Li ◽  
Jinlong Du ◽  
Ruochen Shi ◽  
Yang Huang ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Energy Loss ◽  
Phonon Dispersion ◽  
Hexagonal Boron Nitride ◽  
Real Space ◽  
Boron Nitride Nanotubes ◽  
Detection Sensitivity ◽  
Optical Modes ◽  
Optical And Mechanical Properties ◽  
Energy And Momentum

AbstractDirectly mapping local phonon dispersion in individual nanostructures can advance our understanding of their thermal, optical, and mechanical properties. However, this requires high detection sensitivity and combined spatial, energy and momentum resolutions, thus has been elusive. Here, we demonstrate a four-dimensional electron energy loss spectroscopy technique, and present position-dependent phonon dispersion measurements in individual boron nitride nanotubes. By scanning the electron beam in real space while monitoring both the energy loss and the momentum transfer, we are able to reveal position- and momentum-dependent lattice vibrations at nanometer scale. Our measurements show that the phonon dispersion of multi-walled nanotubes is locally close to hexagonal-boron nitride crystals. Interestingly, acoustic phonons are sensitive to defect scattering, while optical modes are insensitive to small voids. This work not only provides insights into vibrational properties of boron nitride nanotubes, but also demonstrates potential of the developed technique in nanoscale phonon dispersion measurements.

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