Preprint Article Version 2 Preserved in Portico This version is not peer-reviewed

Precise Catalyst Production for Carbon Nanotube Synthesis with Targeted Structure Enrichment

Version 1 : Received: 29 August 2020 / Approved: 30 August 2020 / Online: 30 August 2020 (15:22:52 CEST)
Version 2 : Received: 16 September 2020 / Approved: 17 September 2020 / Online: 17 September 2020 (12:01:44 CEST)

A peer-reviewed article of this Preprint also exists.

Zhang, X.; Deng, Y.; Graves, B.; De Volder, M.; Boies, A. Precise Catalyst Production for Carbon Nanotube Synthesis with Targeted Structure Enrichment. Catalysts 2020, 10, 1087. Zhang, X.; Deng, Y.; Graves, B.; De Volder, M.; Boies, A. Precise Catalyst Production for Carbon Nanotube Synthesis with Targeted Structure Enrichment. Catalysts 2020, 10, 1087.

Journal reference: Catalysts 2020, 10, 1087
DOI: 10.3390/catal10091087

Abstract

The direct growth of single-walled carbon nanotubes (SWCNTs) with a narrow distribution of diameter or chirality remains elusive despite significant benefits in properties and applications. Nanoparticle catalysts are vital for SWCNT synthesis, but how to precisely manipulate their chemistry, size, concentration, and deposition remains difficult, especially within a continuous production process from the gas-phase. Here, we demonstrate the preparation of W6Co7 alloyed nanoparticle catalysts with precisely tunable stoichiometry using electrospray, which remain solid state during SWCNT growth. We also demonstrate continuous production of liquid iron nanoparticles with in-line size selection. With the precise size manipulation of catalysts in the range of 1-5 nm, and a nearly monodisperse distribution (σg < 1.2), an excellent size selection of SWCNT can be achieved. All of the presented techniques show great potential to facilitate the realization of single-chirality SWCNT production.

Subject Areas

carbon nanotube; catalyst; alloy; nanoparticle; electrospray

Comments (1)

Comment 1
Received: 17 September 2020
Commenter: Xiao Zhang
Commenter's Conflict of Interests: Author
Comment: Line 71          Add a missed “-” or “to”.“with diameter range within 110 nm” is changed into “with diameter range within 1 to 10 nm”. Line 292-296 Add more details on CNT growth process.“oNPs are first reduced in H2 with the temperature slowly rising to 400°C to obtain mNPs. Ethanol vapor as the carbon feedstock is introduced into the reaction zone (850°C) in an Ar carrier gas stream. After a set growth time, the carbon-rich environment is expelled by H2, and the samples are cooled to room temperature.”  is changed into “To avoid or reduce possible aggregation, oNPs are first reduced in H2 with the temperature slowly rising to 400°C to obtain mNPs. Then the temperature is quickly raised to 850°C(100 K/min). Ethanol vapor as the carbon feedstock is introduced immediately when the final temperature is reached (850°C) in an Ar carrier gas stream. The growth time is set to only 10 min. After growth, the carbon-rich environment is expelled by H2, and the samples are cooled to room temperature. ” Many places To avoid misleading readers that we only produce SWCNTs, we change some “SWCNTs” to “CNTs”, particularly in alloyed NPs section.  Line 207-208 Add the explanation on method of Raman RBM mapping.“…Resonant Raman spectroscopy shows the RBM peaks of SWCNTs in the laser spot excited with laser phonons[3, 13]. Based on RBM peaks frequency (ωRBM) to the diameter of SWCNT (dt) relationship for samples grown on SiO2/Si substrates[14],…” is changed into “…Resonant Raman spectroscopy shows the RBM peaks of SWCNTs in the laser spot excited with laser phonons[3,13]. We follow our reported method[8] on Raman mapping characterization and data analysis. Based on RBM peaks frequency (ωRBM) to the diameter of SWCNT (dt) relationship for samples grown on SiO2/Si substrates[14],…”. Line 130-134 To clarify the misunderstanding on SEM of individual CNTs in original manuscript, we add “…Moreover, it is worth noting that, in SEM images of CNTs laying on insulating substrate (SiO2/Si) obtained with low accelerating voltage (1-3 kV), the bright line in images (Fig.3a-b) originates from not only the CNT itself, but also from the adjacent zone of substrate affected by the CNT[23]. Therefore, the diameter of bright lines cannot represent those of CNTs.” Line 386-388 The corresponding #23 reference is consequently added. Line 155-156 “relatively” is changed into “comparatively” Line 353 Update details of  #8 reference

Line 113-115 We add explanation on the identification of crystal structure.“We believe the alloyed-mNPs are W6Co7 alloyed single crystals.” is changed into “…We suggest the alloyed-mNPs are W6Co7 alloyed single crystals (details of the crystal structure identification can be found in supplementary material).”  A supplementary material file has been added as request by reviewer to give details on crystal structure identification.  Line 158-163 We add details on yield of electrospray method“which is a compromise to reach higher catalyst production rate and collection efficiency. Considering the unique advantage of electrospray method on the manipulation of stoichiometry in the nano-catalyst…” is changed into“which is a compromise to reach higher catalyst production rate and collection efficiency. Currently, the yield of our electrospray method is around 101-103 #/cm3/min, which set up many difficulties on characterization and size selection. However, significant advancements in electrospray have been made in recent years as a part of a large effort by the synthesis community [24]. The yield can also be improved in the future by using the electrospray with multi cone-jets, instead of a single one used here. Considering the unique advantage of electrospray method on the manipulation of stoichiometry in the nano-catalyst…”  Line 395-397 The corresponding #24 reference is consequently added.

Fig 6 is also changed into a new version
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