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Hydrogen-assisted spark discharge generated metal nanoparticles to prevent oxide formation

Hallberg, R. T. LU ; Ludvigsson, L. LU ; Preger, C. LU ; Meuller, B. O. LU ; Dick, K. A. LU and Messing, M. E. LU (2017) In Aerosol Science and Technology
Abstract

There exists a demand for production of metal nanoparticles for today's emerging nanotechnology. Aerosol-generated metal nanoparticles can oxidize during particle formation due to impurities in the carrier gas. One method to produce unoxidized metal nanoparticles is to first generate metal oxides and then reduce them during sintering. Here, we propose to instead prevent oxidation by introducing the reducing agent already at particle formation. We show that by mixing 5% hydrogen into the nitrogen carrier gas, we can generate single crystalline metal nanoparticles by spark discharge from gold, cobalt, bismuth, and tin electrodes. The non-noble nanoparticles exhibit signs of surface oxidation likely formed post-deposition when exposed to... (More)

There exists a demand for production of metal nanoparticles for today's emerging nanotechnology. Aerosol-generated metal nanoparticles can oxidize during particle formation due to impurities in the carrier gas. One method to produce unoxidized metal nanoparticles is to first generate metal oxides and then reduce them during sintering. Here, we propose to instead prevent oxidation by introducing the reducing agent already at particle formation. We show that by mixing 5% hydrogen into the nitrogen carrier gas, we can generate single crystalline metal nanoparticles by spark discharge from gold, cobalt, bismuth, and tin electrodes. The non-noble nanoparticles exhibit signs of surface oxidation likely formed post-deposition when exposed to air. Nanoparticles generated without hydrogen are found to be primarily polycrystalline and oxidized. To demonstrate the advantages of supplying the reducing agent at generation, we compare to nanoparticles that are generated in nitrogen and sintered in a hydrogen mixture. For bismuth and tin, the crystal quality of the particles after sintering is considerably higher when hydrogen is introduced at particle generation compared to at sintering, whereas for cobalt it is equally effective to only add hydrogen at sintering. We propose that hydrogen present at particle generation prevents the formation of oxide primary particles, thus improving the ability to sinter the nanoparticles to compact and single crystals of metal. This method is general and can be applied to other aerosol generation systems, to improve the generation of size-controlled nanoparticles of non-noble metals with a suitable reducing agent.

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author
organization
publishing date
type
Contribution to journal
publication status
epub
subject
in
Aerosol Science and Technology
pages
12 pages
publisher
Taylor & Francis
external identifiers
  • scopus:85038629216
ISSN
0278-6826
DOI
10.1080/02786826.2017.1411580
language
English
LU publication?
yes
id
5b4f3b90-d46e-4645-b0ce-8596366b82bc
date added to LUP
2018-01-03 09:19:51
date last changed
2018-01-03 09:19:51
@article{5b4f3b90-d46e-4645-b0ce-8596366b82bc,
  abstract     = {<p>There exists a demand for production of metal nanoparticles for today's emerging nanotechnology. Aerosol-generated metal nanoparticles can oxidize during particle formation due to impurities in the carrier gas. One method to produce unoxidized metal nanoparticles is to first generate metal oxides and then reduce them during sintering. Here, we propose to instead prevent oxidation by introducing the reducing agent already at particle formation. We show that by mixing 5% hydrogen into the nitrogen carrier gas, we can generate single crystalline metal nanoparticles by spark discharge from gold, cobalt, bismuth, and tin electrodes. The non-noble nanoparticles exhibit signs of surface oxidation likely formed post-deposition when exposed to air. Nanoparticles generated without hydrogen are found to be primarily polycrystalline and oxidized. To demonstrate the advantages of supplying the reducing agent at generation, we compare to nanoparticles that are generated in nitrogen and sintered in a hydrogen mixture. For bismuth and tin, the crystal quality of the particles after sintering is considerably higher when hydrogen is introduced at particle generation compared to at sintering, whereas for cobalt it is equally effective to only add hydrogen at sintering. We propose that hydrogen present at particle generation prevents the formation of oxide primary particles, thus improving the ability to sinter the nanoparticles to compact and single crystals of metal. This method is general and can be applied to other aerosol generation systems, to improve the generation of size-controlled nanoparticles of non-noble metals with a suitable reducing agent.</p>},
  author       = {Hallberg, R. T. and Ludvigsson, L. and Preger, C. and Meuller, B. O. and Dick, K. A. and Messing, M. E.},
  issn         = {0278-6826},
  language     = {eng},
  month        = {12},
  pages        = {12},
  publisher    = {Taylor & Francis},
  series       = {Aerosol Science and Technology},
  title        = {Hydrogen-assisted spark discharge generated metal nanoparticles to prevent oxide formation},
  url          = {http://dx.doi.org/10.1080/02786826.2017.1411580},
  year         = {2017},
}