Publication detail

Mechanism of WS2 Nanotube Formation Revealed by in Situ/ex Situ Imaging

KUNDRÁT, V. NOVÁK, L. BUKVIŠOVÁ, K. ZÁLEŠÁK, J. KOLÍBALOVÁ, E. ROSENTSVEIG, R. SREEDHARA, M. B. SHALOM, H. YADGAROV, L. ZAK, A. KOLÍBAL, M. TENNE, R.

Original Title

Mechanism of WS2 Nanotube Formation Revealed by in Situ/ex Situ Imaging

Type

journal article in Web of Science

Language

English

Original Abstract

Multiwall WS2 nanotubes have been synthesized from W18O49 nanowhiskers in substantial amounts for more than a decade. The established growth model is based on the "surface-inward" mechanism, whereby the high-temperature reaction with H2S starts on the nanowhisker surface, and the oxide-to-sulfide conversion progresses inward until hollow-core multiwall WS2 nanotubes are obtained. In the present work, an upgraded in situ SEM mu Reactor with H-2 and H2S sources has been conceived to study the growth mechanism in detail. A hitherto undescribed growth mechanism, named "receding oxide core", which complements the "surface-inward" model, is observed and kinetically evaluated. Initially, the nanowhisker is passivated by several WS2 layers via the surface-inward reaction. At this point, the diffusion of H2S through the already existing outer layers becomes exceedingly sluggish, and the surface-inward reaction is slowed down appreciably. Subsequently, the tungsten suboxide core is anisotropically volatilized within the core close to its tips. The oxide vapors within the core lead to its partial out-diffusion, partially forming a cavity that expands with reaction time. Additionally, the oxide vapors react with the internalized H2S gas, forming fresh WS2 layers in the cavity of the nascent nanotube. The rate of the receding oxide core mode increases with temperatures above 900 degrees C. The growth of nanotubes in the atmospheric pressure flow reactor is carried out as well, showing that the proposed growth model (receding oxide core) is also relevant under regular reaction parameters. The current study comprehensively explains the WS2 nanotube growth mechanism, combining the known model with contemporary insight.

Keywords

WS2 nanotube; sulfidation; in situ; ex situ; electronmicroscopy; reaction mechanism

Authors

KUNDRÁT, V.; NOVÁK, L.; BUKVIŠOVÁ, K.; ZÁLEŠÁK, J.; KOLÍBALOVÁ, E.; ROSENTSVEIG, R.; SREEDHARA, M. B.; SHALOM, H.; YADGAROV, L.; ZAK, A.; KOLÍBAL, M.; TENNE, R.

Released

3. 5. 2024

Publisher

AMER CHEMICAL SOC

Location

WASHINGTON

ISBN

1936-0851

Periodical

ACS Nano

Year of study

18

Number

19

State

United States of America

Pages from

12284

Pages to

12294

Pages count

11

URL

https://pubs.acs.org/doi/10.1021/acsnano.4c01150

BibTex

@article{BUT188679,
  author="KUNDRÁT, V. and NOVÁK, L. and BUKVIŠOVÁ, K. and ZÁLEŠÁK, J. and KOLÍBALOVÁ, E. and ROSENTSVEIG, R. and SREEDHARA, M. B. and SHALOM, H. and YADGAROV, L. and ZAK, A. and KOLÍBAL, M. and TENNE, R.",
  title="Mechanism of WS2 Nanotube Formation Revealed by in Situ/ex Situ Imaging",
  journal="ACS Nano",
  year="2024",
  volume="18",
  number="19",
  pages="12284--12294",
  doi="10.1021/acsnano.4c01150",
  issn="1936-0851",
  url="https://pubs.acs.org/doi/10.1021/acsnano.4c01150"
}