| Download | - View final version: Role of hydrogen in high-yield growth of boron nitride nanotubes at atmospheric pressure by induction thermal plasma (PDF, 1.1 MiB)
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| DOI | Resolve DOI: https://doi.org/10.1021/acsnano.7b08708 |
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| Author | Search for: Kim, Keun Su1; Search for: Couillard, Martin2; Search for: Shin, Homin1; Search for: Plunkett, Mark1; Search for: Ruth, Dean1; Search for: Kingston, Christopher T.1; Search for: Simard, Benoit1 |
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| Affiliation | - National Research Council of Canada. Security and Disruptive Technologies
- National Research Council of Canada. Energy, Mining and Environment
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| Format | Text, Article |
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| Subject | boron nitride nanotubes; density functional theory; hydrogen-catalyzed; induction thermal plasma; optical emission spectroscopy; scalable manufacturing; thermofluid simulation |
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| Abstract | We recently demonstrated scalable manufacturing of boron nitride nanotubes (BNNTs) directly from hexagonal BN (hBN) powder by using induction thermal plasma, with a high-yield rate approaching 20 g/h. The main finding was that the presence of hydrogen is crucial for the high-yield growth of BNNTs. Here we investigate the detailed role of hydrogen by numerical modeling and in situ optical emission spectroscopy (OES) and reveal that both the thermofluidic fields and chemical pathways are significantly altered by hydrogen in favor of rapid growth of BNNTs. The numerical simulation indicated improved particle heating and quenching rates (∼105 K/s) due to the high thermal conductivity of hydrogen over the temperature range of 3500–4000 K. These are crucial for the complete vaporization of the hBN feedstock and rapid formation of nanosized B droplets for the subsequent BNNT growth. Hydrogen is also found to extend the active BNNT growth zone toward the reactor downstream, maintaining the gas temperature above the B solidification limit (∼2300 K) by releasing the recombination heat of H atoms, which starts at 3800 K. The OES study revealed that H radicals also stabilize B or N radicals from dissociation of the feedstock as BH and NH radicals while suppressing the formation of N2 or N2+ species. Our density functional theory calculations showed that such radicals can provide faster chemical pathways for the formation of BN compared with relatively inert N2. |
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| Publication date | 2018-01-04 |
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| Publisher | American Chemical Society |
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| In | |
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| Language | English |
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| Peer reviewed | Yes |
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| NPARC number | 23003938 |
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| Export citation | Export as RIS |
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| Report a correction | Report a correction (opens in a new tab) |
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| Record identifier | d7016fb9-4b58-4b45-964e-d7f3d10221a3 |
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| Record created | 2018-08-23 |
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| Record modified | 2020-05-30 |
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