A novel mechano-chemical synthesis route for fluorination of hexagonal boron nitride nanosheets

Ahmad, Aqrab ul; Liang, Hongwei; Abbas, Qasim; Ali, Sajid; Iqbal, Muzammil; Farid, Amjad; Abbas, Akmal; Farooq, Zahid

doi:10.1016/j.ceramint.2019.06.164

Cited by 27 publications

(19 citation statements)

References 36 publications

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“…Furthermore, the peak centered 195 eV could be assigned to BF 4 + species following a similar argument that charged ammonium species are located at higher energies than their corresponding neutral nitrogen functionalities in the N1s area 53 – 55 . Lastly, the position of the feature in the F1s area is also in line with the literature regarding the expected position for an F-B functionality 52 . Given all this experimental evidence, the results strongly suggest that the doping is physical in nature.…”

Section: Resultssupporting

confidence: 87%

“…8 c is located in the higher energy regime, it could account for bromine in the form of BF 3 and BF 4 + . This is supported by Ahmad and colleagues' results, who observed a B-F component in a comparable region 52 . Furthermore, the peak centered 195 eV could be assigned to BF 4 + species following a similar argument that charged ammonium species are located at higher energies than their corresponding neutral nitrogen functionalities in the N1s area 53 – 55 .…”

Section: Resultssupporting

confidence: 76%

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Enhancing thermoelectric properties of single-walled carbon nanotubes using halide compounds at room temperature and above

Kumanek

Stando

et al. 2021

Sci Rep

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Carbon nanotubes (CNTs) are materials with exceptional electrical, thermal, mechanical, and optical properties. Ever since it was demonstrated that they also possess interesting thermoelectric properties, they have been considered a promising solution for thermal energy harvesting. In this study, we present a simple method to enhance their performance. For this purpose, thin films obtained from high-quality single-walled CNTs (SWCNTs) were doped with a spectrum of inorganic and organic halide compounds. We studied how incorporating various halide species affects the electrical conductivity, the Seebeck coefficient, and the Power Factor. Since thermoelectric devices operate under non-ambient conditions, we also evaluated these materials' performance at elevated temperatures. Our research shows that appropriate dopant selection can result in almost fivefold improvement to the Power Factor compared to the pristine material. We also demonstrate that the chemical potential of the starting CNT network determines its properties, which is important for deciphering the true impact of chemical and physical functionalization of such ensembles.

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Section: Resultssupporting

confidence: 87%

Section: Resultssupporting

confidence: 76%

Enhancing thermoelectric properties of single-walled carbon nanotubes using halide compounds at room temperature and above

Kumanek

Stando

et al. 2021

Sci Rep

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“…The deconvoluted N(1s) spectra (Figure 1e) display -N-Bbonding around 398.2 eV, assigned to the N-F bond formation. [29,36,37] In general, direct addition of fluorine at the nitrogen site or stable N-F bond formation are not feasible due to both the elements' high electronegative nature. The mechanism of N-F bond formation can be explained with two possibilities: i) the formation of a stable B-F creates a partial positive charge on the adjacent nitrogen atom, which can directly form a bond with fluorine, or ii) addition of two fluorine atoms at the boron site and migration of one of the fluorine atoms to the adjacent nitrogen atom.…”

Section: Resultsmentioning

confidence: 99%

“…Where 101a exhibits a signal at −157 ppm for the FBN 2 group, while 101a and 101b exhibit a 19 F signal at −158 ppm for the F 2 BN 2 − group. [ 40,41 ] Since our material gives a signal at −149 ppm, the difference of <10 ppm is inconsequential in light of the very large chemical shift range for 19 F, [ 37 ] especially since the models are far from ideal.…”

Section: Resultsmentioning

confidence: 99%

Gas‐Phase Fluorination of Hexagonal Boron Nitride

et al. 2021

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Hexagonal boron nitride (hBN) has received much attention in recent years as a 2D dielectric material with potential applications ranging from catalysts to electronics. hBN is a stable covalent compound with a planar hexagonal lattice and is relatively unreactive to most chemical environments, making the chemical functionalization of hBN challenging. Here, a simple, scalable strategy to fluorinate hBN using a direct gas‐phase fluorination technique is reported. The nature of fluorine bonding to the hBN lattice and their chemical coordination are described based on various characterization studies and theoretical models. The fluorine functionalized hBN shows a bandgap reduction and displays a semiconducting behavior due to the fluorination process. Additionally, the fluorinated hBN shows significant improvement in its thermal and friction properties, which could be substantial in applications such as lubricants and thermal fluids. Theory and simulations reveal that the enhanced friction properties of fluorinated hBN result from reduced inter‐planar interaction energy by electrostatic repulsion of intercalated fluorine atoms between hBN layers without significant disruption of the in‐plane lattice. This technique paves the way for the fluorination of several other 2D structures for various applications such as magnetism and functional nanoscale electronic devices.

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“…The production of these dispersions on a large scale requires the exfoliation of the two-dimensional (2D) nanosheets from the three-dimensional (3D) bulk material. Some studies have explored exfoliation methods that can be applied to a variety of 2D materials, including graphene and transition-metal dichalcogenides. − Several groups have attempted to achieve hBN exfoliation in various ways, including the use of solvents, ,,− acids and bases, ,− covalent functionalization, ,,− biomolecules, ,, polymers, ,,− and surfactants, ,− among others. − Amid these many options, surfactants are advantageous for many industrial applications, as they have low toxicity, are inexpensive, and do not disrupt the sp 2 hybridization, and therefore the thermal and mechanical properties of hBN. Despite these advantages, very few surfactants have been tested for the dispersion of hBN.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Exfoliation and Dispersion of Hexagonal Boron Nitride Nanosheets by Surfactants: Implications for Antibacterial and Thermally Resistant Coatings

McWilliams

Martínez-Jiménez

Ya’akobi

et al. 2021

ACS Appl. Nano Mater.

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Hexagonal boron nitride (hBN) is a structural analog of graphene, with unique mechanical, thermal, and optical properties that make it desirable for a variety of applications. Production of stable dispersions of well-exfoliated hBN nanosheets, particularly in a nontoxic and inexpensive way, is an important step in the production of hBN macromaterials on an industrial scale. Here, we investigate the use of surfactants for exfoliating and dispersing hBN in aqueous solution. Dispersions in nine different surfactants and water were compared based on dispersion yield, quality, and stability. It was revealed that at low centrifugal force, large-molecular-weight nonionic surfactants disperse the most material. In contrast, when stronger centrifugation is applied, all surfactants produce similar dispersion yields, with dispersions in ionic surfactants containing significantly more exfoliated nanosheets and remaining stable over much longer periods of time. Finally, to demonstrate the scalability and effectiveness of these systems for making macroscopic materials, a dispersion of hBN in sodium dodecyl sulfate (SDS) was used to produce a transparent hBN film that can be deposited on glass and potentially used as an antibacterial or thermally resistant coating.

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A novel mechano-chemical synthesis route for fluorination of hexagonal boron nitride nanosheets

Cited by 27 publications

References 36 publications

Enhancing thermoelectric properties of single-walled carbon nanotubes using halide compounds at room temperature and above

Enhancing thermoelectric properties of single-walled carbon nanotubes using halide compounds at room temperature and above

Gas‐Phase Fluorination of Hexagonal Boron Nitride

Understanding the Exfoliation and Dispersion of Hexagonal Boron Nitride Nanosheets by Surfactants: Implications for Antibacterial and Thermally Resistant Coatings

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