The influence of H2 and NH3 on catalyst nanoparticle formation and carbon nanotube growth

R. Pezone; Sten Vollebregt; P.M. Sarro; S. Unnikrishnan

doi:10.1016/j.carbon.2020.07.045

The influence of H₂ and NH₃ on catalyst nanoparticle formation and carbon nanotube growth

R. Pezone, Sten Vollebregt, P.M. Sarro, S. Unnikrishnan

Electronic Components, Technology and Materials

Research output: Contribution to journal › Article › Scientific › peer-review

4 Citations (Scopus)

64 Downloads (Pure)

Abstract

Control of the morphology of carbon nanotubes (CNT) is fundamental for many applications. It is known that the catalyst distributions influence the vertical alignment and the height of the CNT. In this work we investigate the influence of the pre-anneal time and reductant gases, specifically NH₃ and H₂ as well as combinations thereof, on the nanoparticle (NP) formation and CNT growth. The gases H_2, NH₃ show opposite roles during the dewetting of 1 nm Fe catalyst layer. The H₂ favours uniform NP distributions (mean diameter of 15 nm) and the NH₃ forms large clusters. Playing with double annealing steps H₂- NH₃ we obtained NP with larger mean diameters μ = 20 nm. We observed a mismatch between the diameters of the NP directly after annealing and the CNT after growth, due to a reshaping of the catalyst NP before the CNT nucleation. Furthermore, we found that longer annealing times decrease the CNT forest height and the H₂ exposure during the annealing improves the height and the alignment of the CNT.

Original language	English
Pages (from-to)	384-393
Number of pages	10
Journal	Carbon
Volume	170
DOIs	https://doi.org/10.1016/j.carbon.2020.07.045
Publication status	Published - 2020

Access to Document

10.1016/j.carbon.2020.07.045

1-s2.0-S0008622320307053-mainFinal published version, 3.55 MBLicence: CC BY

Cite this

@article{25af6aa463ce4831b216e9bbec6801ec,

title = "The influence of H2 and NH3 on catalyst nanoparticle formation and carbon nanotube growth",

abstract = "Control of the morphology of carbon nanotubes (CNT) is fundamental for many applications. It is known that the catalyst distributions influence the vertical alignment and the height of the CNT. In this work we investigate the influence of the pre-anneal time and reductant gases, specifically NH3 and H2 as well as combinations thereof, on the nanoparticle (NP) formation and CNT growth. The gases H2, NH3 show opposite roles during the dewetting of 1 nm Fe catalyst layer. The H2 favours uniform NP distributions (mean diameter of 15 nm) and the NH3 forms large clusters. Playing with double annealing steps H2- NH3 we obtained NP with larger mean diameters μ = 20 nm. We observed a mismatch between the diameters of the NP directly after annealing and the CNT after growth, due to a reshaping of the catalyst NP before the CNT nucleation. Furthermore, we found that longer annealing times decrease the CNT forest height and the H2 exposure during the annealing improves the height and the alignment of the CNT.",

author = "R. Pezone and Sten Vollebregt and P.M. Sarro and S. Unnikrishnan",

year = "2020",

doi = "10.1016/j.carbon.2020.07.045",

language = "English",

volume = "170",

pages = "384--393",

journal = "Carbon",

issn = "0008-6223",

publisher = "Elsevier",

}

TY - JOUR

T1 - The influence of H2 and NH3 on catalyst nanoparticle formation and carbon nanotube growth

AU - Pezone, R.

AU - Vollebregt, Sten

AU - Sarro, P.M.

AU - Unnikrishnan, S.

PY - 2020

Y1 - 2020

N2 - Control of the morphology of carbon nanotubes (CNT) is fundamental for many applications. It is known that the catalyst distributions influence the vertical alignment and the height of the CNT. In this work we investigate the influence of the pre-anneal time and reductant gases, specifically NH3 and H2 as well as combinations thereof, on the nanoparticle (NP) formation and CNT growth. The gases H2, NH3 show opposite roles during the dewetting of 1 nm Fe catalyst layer. The H2 favours uniform NP distributions (mean diameter of 15 nm) and the NH3 forms large clusters. Playing with double annealing steps H2- NH3 we obtained NP with larger mean diameters μ = 20 nm. We observed a mismatch between the diameters of the NP directly after annealing and the CNT after growth, due to a reshaping of the catalyst NP before the CNT nucleation. Furthermore, we found that longer annealing times decrease the CNT forest height and the H2 exposure during the annealing improves the height and the alignment of the CNT.

AB - Control of the morphology of carbon nanotubes (CNT) is fundamental for many applications. It is known that the catalyst distributions influence the vertical alignment and the height of the CNT. In this work we investigate the influence of the pre-anneal time and reductant gases, specifically NH3 and H2 as well as combinations thereof, on the nanoparticle (NP) formation and CNT growth. The gases H2, NH3 show opposite roles during the dewetting of 1 nm Fe catalyst layer. The H2 favours uniform NP distributions (mean diameter of 15 nm) and the NH3 forms large clusters. Playing with double annealing steps H2- NH3 we obtained NP with larger mean diameters μ = 20 nm. We observed a mismatch between the diameters of the NP directly after annealing and the CNT after growth, due to a reshaping of the catalyst NP before the CNT nucleation. Furthermore, we found that longer annealing times decrease the CNT forest height and the H2 exposure during the annealing improves the height and the alignment of the CNT.

UR - http://www.scopus.com/inward/record.url?scp=85089936188&partnerID=8YFLogxK

U2 - 10.1016/j.carbon.2020.07.045

DO - 10.1016/j.carbon.2020.07.045

M3 - Article

AN - SCOPUS:85089936188

SN - 0008-6223

VL - 170

SP - 384

EP - 393

JO - Carbon

JF - Carbon

ER -

The influence of H₂ and NH₃ on catalyst nanoparticle formation and carbon nanotube growth

Abstract

Access to Document

Other files and links

Fingerprint

Cite this