Plasma Treatment as a Way of Increasing the Selectivity of Carbon Nanotube Networks for Organic Vapor Sensing Elements

Multi-walled carbon nanotubes networks (MWCNTs) were used as a layer for organic vapor detection. The sensor detects volatile organic compounds (VOC). The gas sensing by MWCNTs is measured by means of macroscopic electrical resistance. The selected solvents had different polarities and volume fractions of saturated vapors. The electrical resistance of MWCNTs increases when exposed to organic solvent vapors, and a reversible reaction is observed when the MWCNT is removed from the vapors. The MWCNTs were modified by means of plasma treatment. For modifications RF plasma in O2 at 50 Pa and an afterglow configuration were used. The modified MWCNTs show an increase in sensitivity caused by creating carboxylic groups on the surface of the carbon nanotubes. It leads, for example, to enhancement of the sensitivity from usual 30 % for heptane at RT to more than 200% after plasma treatment in O2 for 10s.

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Влияние обработки в He:O плазме на структуру многостенных углеродных нанотрубок

Письма в журнал технической физики ◽

10.21883/pjtf.2022.05.52148.18864 ◽

2022 ◽

Vol 48 (5) ◽

pp. 11

Author(s):

В.В. Болотов ◽

Е.В. Князев ◽

С.Н. Несов

Keyword(s):

Carbon Nanotubes ◽

Plasma Treatment ◽

Functional Groups ◽

Electrical Resistance ◽

Chemical Bonds ◽

Graphene Layers ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

The functionalization of multi-walled carbon nanotubes in He:O plasma is investigated. It's shown that plasma treatment leads to the removal of defective outer graphene layers and their fragments due to oxidation. It is established that the surface of functionalized multi-walled carbon nanotubes contains numerous uncoordinated carbon atoms and oxygen-containing functional groups. The preservation of the structure of the internal graphene layers of nanotubes and the formation of broken chemical bonds ensures a decrease in electrical resistance. At the same time, there is a narrowing of the distribution of electrical resistance values of nanotube ensembles.

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Covalent Immobilization of Polyaniline Doped with Ag+ or Cu2+ on Carbon Nanotubes for Ethylene Chemical Sensing

Nanomaterials ◽

10.3390/nano11081993 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1993

Author(s):

Hagai Klein ◽

Karthik Ananth Mani ◽

Vinay Chauhan ◽

Noga Yaakov ◽

Franziska Grzegorzewski ◽

...

Keyword(s):

Carbon Nanotubes ◽

Electrical Resistance ◽

Chemical Sensing ◽

Gas Sensing ◽

Local Environment ◽

Covalent Immobilization ◽

Coordinate Bond ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes ◽

Sensing Performance

Multi-walled carbon nanotubes (MWCNTs) are promising materials for chemical gas sensing because of their high electrical and mechanical properties and significant sensitivity to changes in the local environment. However, high-content MWCNT films suffer from the low tunability of the electrical resistance, which is crucial for high chemoresistive sensing performance. This study reports the conjugation of MWCNTs and oligomers of polyaniline (PANI) doped with Ag+ or Cu2+ incorporated into a PVC/polyacrylate. MWCNTs were sonicated in n-methyl pyrrolidine (NMP), and PANI was conjugated via a 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and an N-hydroxysuccinimide (EDC/NHS) process. MWCNT/PANI Ag+ or Cu2+ conjugates were doped to form a coordinate bond. The doped conjugates were successfully incorporated into the PVC/polyacrylate. These MWCNT/PANI conjugates doped were exposed to different concentrations of ethylene gas to examine their feasibility for ethylene detection.

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Gas sensing properties of tin dioxide coated onto multi-walled carbon nanotubes

Thin Solid Films ◽

10.1016/j.tsf.2005.11.018 ◽

2006 ◽

Vol 497 (1-2) ◽

pp. 355-360 ◽

Cited By ~ 76

Author(s):

Yan-Li Liu ◽

Hai-Feng Yang ◽

Yu Yang ◽

Zhi-Min Liu ◽

Guo-Li Shen ◽

...

Keyword(s):

Carbon Nanotubes ◽

Tin Dioxide ◽

Gas Sensing ◽

Sensing Properties ◽

Gas Sensing Properties ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

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The Multifunctional Composite on the Base of Carbon Nanotubes Network and its Use as a Passive Antenna and Gas Sensing Element

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.605.322 ◽

2014 ◽

Vol 605 ◽

pp. 322-325

Author(s):

Robert Olejnik ◽

Jiri Matyas ◽

Petr Slobodian ◽

Karel Vlcek

Keyword(s):

Carbon Nanotubes ◽

Gas Sensing ◽

Aqueous Suspension ◽

Multiwall Carbon Nanotubes ◽

Sensing Element ◽

Vapor Detection ◽

Filtration Method ◽

Wide Range ◽

Passive Antenna ◽

Nonpolar Organic

Carbon nanotubes in the form of entangled network can be used as a multifunctional composite material for a wide range of using. A new and perspective usage is a passive antenna and gas sensing element. The antenna works well at 1.284 GHz. The local reflection minimum is 11.48 dB. The reflection coefficient r=0.2667. The transmission power in this frequency is 93%. Multiwall carbon nanotubes (MWCNT) network Buckypaper was made by the vacuum filtration method of MWCNT aqueous suspension. The sensitivity of multi-wall carbon nanotube (MWCNT) networks of randomly entangled pure and HNO3 oxidized nanotubes to polar and nonpolar organic vapors (ethanol, heptane), has been investigated by resistance measurements. The results demonstrate that the network electrical resistance increases when exposed to organic solvent vapors, and a reversible reaction is observed when the sample is removed from the vapors. The investigated MWCNT networks could be potentially used as sensing elements for sensitive and selective organic vapor detection.

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