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Title: Effects of O 2 plasma and UV-O 3 assisted surface activation on high sensitivity metal oxide functionalized multiwalled carbon nanotube CH 4 sensors

Abstract

We present a comparative analysis of UV-O 3 (UVO) and O 2 plasma-based surface activation processes of multi-walled carbon nanotubes (MWCNTs) enabling highly effective functionalization with metal oxide nanocrystals (MONCs). Experimental results from transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy show that by forming COOH (carboxyl), C-OH (hydroxyl), and C=O (carbonyl) groups on the MWCNT surface that act as active nucleation sites, O 2 plasma and UVO-based dry pre-treatment techniques greatly enhance the affinity between MWCNT surface and the functionalizing MONCs. MONCs, such as ZnO and SnO 2, deposited by atomic layer deposition (ALD) technique, were implemented as the functionalizing material following UVO and O 2 plasma activation of MWCNTs. In conclusion, a comparative study on the relative resistance changes of O 2 plasma and UVO activated MWCNT functionalized with MONC in the presence of 10 ppm methane (CH 4) in air, is presented as well.

Authors:
 [1];  [1];  [2];  [2];  [1];  [3];  [4];  [1]
  1. Univ. of Illinois, at Chicago, Chicago, IL (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. U.S. Environmental Protection Agency, Las Vegas, NV (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Scientific User Facilities Division
OSTI Identifier:
1393949
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films
Additional Journal Information:
Journal Volume: 35; Journal Issue: 6; Journal ID: ISSN 0734-2101
Publisher:
American Vacuum Society
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 54 ENVIRONMENTAL SCIENCES; Carbon Nanotube; Gas sensor; Methane

Citation Formats

Humayun, Md Tanim, Sainato, Michela, Divan, Ralu, Rosenberg, Richard A., Sahagun, Alvaro, Gundel, Lara, Solomon, Paul A., and Paprotny, Igor. Effects of O2 plasma and UV-O3 assisted surface activation on high sensitivity metal oxide functionalized multiwalled carbon nanotube CH4 sensors. United States: N. p., 2017. Web. doi:10.1116/1.4993579.
Humayun, Md Tanim, Sainato, Michela, Divan, Ralu, Rosenberg, Richard A., Sahagun, Alvaro, Gundel, Lara, Solomon, Paul A., & Paprotny, Igor. Effects of O2 plasma and UV-O3 assisted surface activation on high sensitivity metal oxide functionalized multiwalled carbon nanotube CH4 sensors. United States. doi:10.1116/1.4993579.
Humayun, Md Tanim, Sainato, Michela, Divan, Ralu, Rosenberg, Richard A., Sahagun, Alvaro, Gundel, Lara, Solomon, Paul A., and Paprotny, Igor. 2017. "Effects of O2 plasma and UV-O3 assisted surface activation on high sensitivity metal oxide functionalized multiwalled carbon nanotube CH4 sensors". United States. doi:10.1116/1.4993579.
@article{osti_1393949,
title = {Effects of O2 plasma and UV-O3 assisted surface activation on high sensitivity metal oxide functionalized multiwalled carbon nanotube CH4 sensors},
author = {Humayun, Md Tanim and Sainato, Michela and Divan, Ralu and Rosenberg, Richard A. and Sahagun, Alvaro and Gundel, Lara and Solomon, Paul A. and Paprotny, Igor},
abstractNote = {We present a comparative analysis of UV-O3 (UVO) and O2 plasma-based surface activation processes of multi-walled carbon nanotubes (MWCNTs) enabling highly effective functionalization with metal oxide nanocrystals (MONCs). Experimental results from transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy show that by forming COOH (carboxyl), C-OH (hydroxyl), and C=O (carbonyl) groups on the MWCNT surface that act as active nucleation sites, O2 plasma and UVO-based dry pre-treatment techniques greatly enhance the affinity between MWCNT surface and the functionalizing MONCs. MONCs, such as ZnO and SnO2, deposited by atomic layer deposition (ALD) technique, were implemented as the functionalizing material following UVO and O2 plasma activation of MWCNTs. In conclusion, a comparative study on the relative resistance changes of O2 plasma and UVO activated MWCNT functionalized with MONC in the presence of 10 ppm methane (CH4) in air, is presented as well.},
doi = {10.1116/1.4993579},
journal = {Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films},
number = 6,
volume = 35,
place = {United States},
year = 2017,
month = 7
}

Journal Article:
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  • We have shown that the sensitivity of carbon nanotube (CNT) based sensors can be enhanced as high as 74 times through surface modification by using the inductively coupled plasma chemical vapor deposition method with oxygen. The plasma treatment power was maintained as low as 10 W within 20 s, and the oxygen plasma was generated far away from the sensors to minimize the plasma damage. From X-ray photoelectron spectroscopy analysis, we found that the concentration of oxygen increased with the plasma treatment time, which implies that oxygen functional groups or defect sites were generated on the CNT surface.
  • The effect of the functionalization of multiwalled carbon nanotube on the structure and electrical properties of composites was investigated. Samples based on epoxy resin with different weight percentage of MWCNTs were prepared and characterized. The interaction between MWCNT & epoxy resin was noticed by Fourier transform infrared spectroscopy (FTIR). The structure of functionalized multiwalled carbon nanotube (f-MWCNT) reinforced epoxy composite was studied by field emission scanning electron microscope (FESEM). The dispersion of f-MWCNT in epoxy resin was evidenced by high resolution transmission electron microscope (HRTEM). Electrical properties of epoxy/f-MWCNT nanocomposites were measured & the result indicated that the conductivity increasedmore » with increasing concentration of f-MWCNTs.« less
  • Chemoresistive sensors based on multiwalled carbon nanotubes (MWCNTs) functionalized with SnO 2 nanocrystals (NCs) have great potential for detecting trace gases at low concentrations (single ppm levels) at room temperature, because the SnO 2 nanocrystals act as active sites for the chemisorption of gas molecules, and carbon nanotubes (CNTs) act as an excellent current carrying platform, allowing the adsorption of gas on SnO 2 to modulate the resistance of the CNTs. However, uniform conjugation of SnO 2 NCs with MWCNTs is challenging. An effective atomic layer deposition based approach to functionalize the surface of MWCNTs with SnO 2 NCs, resultingmore » in a novel CH 4 sensor with 10 ppm sensitivity, is presented in this paper. Scanning electron microscopy, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy, and Raman spectroscopy were implemented to study the morphology, elemental composition, and the crystal quality of SnO 2 functionalized MWCNTs. High resolution TEM images showed that the crystal quality of the functionalizing SnO 2 NCs was of high quality with clear lattice fringes and the dimension almost three times smaller than shown thus far in literature. A lift-off based photolithography technique comprising bilayer photoresists was optimized to fabricate SnO 2 functionalized MWCNTs-based chemoresistor sensor, which at room temperature can reliably sense below 10 ppm of CH4 in air. Such low level gas sensitivity, with significant reversible relative resistance change, is believed to be the direct result of the successful functionalization of the MWCNT surface by SnO 2 NCs.« less
  • Chemoresistive sensors based on multiwalled carbon nanotubes (MWCNTs) functionalized with SnO{sub 2} nanocrystals (NCs) have great potential for detecting trace gases at low concentrations (single ppm levels) at room temperature, because the SnO{sub 2} nanocrystals act as active sites for the chemisorption of gas molecules, and carbon nanotubes (CNTs) act as an excellent current carrying platform, allowing the adsorption of gas on SnO{sub 2} to modulate the resistance of the CNTs. However, uniform conjugation of SnO{sub 2} NCs with MWCNTs is challenging. An effective atomic layer deposition based approach to functionalize the surface of MWCNTs with SnO{sub 2} NCs, resultingmore » in a novel CH{sub 4} sensor with 10 ppm sensitivity, is presented in this paper. Scanning electron microscopy, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy, and Raman spectroscopy were implemented to study the morphology, elemental composition, and the crystal quality of SnO{sub 2} functionalized MWCNTs. High resolution TEM images showed that the crystal quality of the functionalizing SnO{sub 2} NCs was of high quality with clear lattice fringes and the dimension almost three times smaller than shown thus far in literature. A lift-off based photolithography technique comprising bilayer photoresists was optimized to fabricate SnO{sub 2} functionalized MWCNTs-based chemoresistor sensor, which at room temperature can reliably sense below 10 ppm of CH{sub 4} in air. Such low level gas sensitivity, with significant reversible relative resistance change, is believed to be the direct result of the successful functionalization of the MWCNT surface by SnO{sub 2} NCs.« less
  • Single (SWNTs) and multiwalled (MWNTs) carbon nanotubes were functionalized with a titanium alkoxide catalyst through a Diels-Alder cycloaddition reaction. The catalyst-functionalized carbon nanotubes (CNTs) were used for the surface initiated titanium-mediated coordination polymerizations of L-lactide (L-LA), -caprolactone (-CL) and n-hexyl isocyanate (HIC) employing the grafting from technique. 1H NMR, IR and Raman spectra showed that the precursor catalyst was successfully synthesized and covalently attached on the CNTs surface. Thermogravimetric analysis (TGA) revealed that the grafted poly(L-lactide) (PLLA) content could be controlled with time. The final polymer-grafted CNTs were readily dissolved in organic solvents as compared to the insoluble pristine andmore » catalyst-functionalized CNTs. The presence of thick layers of polymers around the CNTs was observed through transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) proved that the glass transition (Tg) and melting (Tm) temperatures of the PLLA are affected by the presence of the CNTs, while PLLA R-helix conformation remains intact, as revealed by the circular dichroism (CD) spectra.« less