scholarly journals A Room Temperature VOCs Gas Sensor Based on a Layer by Layer Multi-Walled Carbon Nanotubes/Poly-ethylene Glycol Composite

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3113 ◽  
Author(s):  
Zitao Liu ◽  
Tuoyu Yang ◽  
Ying Dong ◽  
Xiaohao Wang
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensor ◽  
Room Temperature ◽  
High Sensitivity ◽  
Fast Response ◽  
Layer By Layer ◽  
Resistance Change ◽  
Multi Walled Carbon Nanotubes ◽  
Electric Nose ◽  
Walled Carbon Nanotubes

Sensitive detection of volatile organic compounds (VOCs) is significant for environmental monitoring and medical applications. In this work, multi-walled carbon nanotubes (MWCNTs) and polyethylene glycol (PEG) that have good adsorption for VOCs, were sprayed layer by layer on an interdigitated electrode (IDE) to build a sensitive VOCs gas sensor. The relative resistance change (△R/R) when the sensor was exposed to VOCs was measured. The sensor showed high sensitivity to acetone, ethanol, isopropanol and isoprene with fast response (110 ± 5 s) and recovery (152 ± 5 s) at room temperature, and the lower detection limit (LDL) of the sensor reached 9 ppm. With the micro-fabricated IDE structure, the sensor can be easily built into an electric nose for VOC recognition and measurement.

Effect of Operating Temperature on Characteristics of Single-Walled Carbon Nanotubes Gas Sensor

2005 ◽  
Vol 486-487 ◽  
pp. 485-488 ◽  
Author(s):  
Hong Quang Nguyen ◽  
Mai Van Trinh ◽  
Jeung Soo Huh
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensor ◽  
Gas Adsorption ◽  
Operating Temperature ◽  
High Sensitivity ◽  
Single Walled Carbon Nanotubes ◽  
Fast Response ◽  
Carrier Gas ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

The effect of operating temperature on characteristics of single-walled carbon nanotubes (SWNT) based gas sensor was investigated. SWNT-based sensor was fabricated from SWNT powder (Iljin Nanotech, Korea) by screen-printing method. SWNT powder (30 mg, AP grade) was dispersed into 0.78 gram a-terpineol (Aldrich) by ultrasonic vibration for 1 hour then stirred manually for 1 hour to increase adhesion. From this condensed solution, a thick film of SWNT was printed onto alumina substrates. The film then was sintered at 300oC for 2 hours to remove residual impurities. Upon exposure to some gases such as nitrogen, ammonia or nitric oxide, resistance of the sensor dramatically changes due to gas adsorption. In our experiments, SWNT-based sensor was employed to detect NH3 gas in N2 ambience. After saturated of N2, the sensor exposes to NH3 with various concentrations (from 5 ppm to 100 ppm, diluted by N2 as carrier gas). This sensor exhibits a fast response, high sensitivity but slow recovery at room temperature. By heating at high temperature and increasing the flow-rate of carrier gas, NH3 gas desorbs easily and recovery of the sensor improved. The heating also influenced the characteristics of sensors such as response and reproducibility. Other special changes in electric property of SWNT-based sensor caused by heating are also discussed.

scholarly journals Room temperature Suzuki coupling of aryl iodides, bromides, and chlorides using a heterogeneous carbon nanotube-palladium nanohybrid catalyst

2015 ◽  
Vol 5 (4) ◽  
pp. 2388-2392 ◽  
Author(s):  
Dhanaji V. Jawale ◽  
Edmond Gravel ◽  
Caroline Boudet ◽  
Nimesh Shah ◽  
Valérie Geertsen ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Palladium Nanoparticles ◽  
Room Temperature ◽  
Suzuki Coupling ◽  
Layer By Layer ◽  
Aryl Iodides ◽  
Multi Walled Carbon Nanotubes ◽  
Heterogenous Catalyst ◽  
Walled Carbon Nanotubes

Palladium nanoparticles were immobilized on multi-walled carbon nanotubes by a layer-by-layer approach, resulting in a well-defined assembly that was used as a heterogenous catalyst in Suzuki couplings.

A Specific NH3 Gas Sensor of a Thick MWCNTs-OH Network for Detection at Room Temperature

2019 ◽  
Vol 56 ◽  
pp. 98-108 ◽  
Author(s):  
Afnan H. Al-Husseini ◽  
Wasan R. Saleh ◽  
Abdulkareem M.A. Al-Sammarraie
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensor ◽  
Room Temperature ◽  
Preparation Method ◽  
Ambient Air ◽  
Good Sensitivity ◽  
Filtration Method ◽  
Multi Walled Carbon Nanotubes ◽  
Suspension Filtration ◽  
Walled Carbon Nanotubes

NH3gas sensor was fabricated based on deposited of Functionalized Multi-Walled Carbon Nanotubes (MWCNTs-OH) suspension on filter paper substrates using suspension filtration method. The structural, morphological and optical properties of the MWCNTs film were characterized by XRD, AFM and FTIR techniques. XRD measurement confirmed that the structure of MWCNTs is not affected by the preparation method. The AFM images reflected highly ordered network in the form of a mat. The functional groups and types of bonding have appeared in the FTIR spectra. The fingerprint (C-C stretch) of MWCNTs appears in 1365 cm-1, and the backbone of CNTs observed at 1645 cm-1. A homemade sensing device was used to evaluate the fabrication network toward NH3gas at ppm levels as well as the response to sensitivity by changing the concentration. MWCNTs-OH network of 8mm thickness showed an increase in resistance upon exposure to the NH3gas. The sensor exhibits a good sensitivity for low concentration of NH3gas at room temperature. The sensitivities of the network were 2.5% at 14ppm, 5.3% at 27ppm and 17.6% at 68ppm. Further investigations showed that the network was specific sensitive to NH3gas in the environment and not affected by the amount of ambient air.

Specific NH3 Gas Sensor Worked at Room Temperature Based on MWCNTs-OH Network

2018 ◽  
Vol 23 ◽  
pp. 8-16 ◽  
Author(s):  
Afnan H. Al-Husseini ◽  
Abdulkareem M. A. Al-Sammarraie ◽  
Wasan R. Saleh
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensor ◽  
Room Temperature ◽  
Ambient Air ◽  
Close Packing ◽  
Absorbance Spectrum ◽  
Sem Images ◽  
Vacuum Filtration ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Functionalized Multi-Walled Carbon Nanotubes (MWCNTs-OH) network with thickness 4μm was made by the vacuum filtration from suspension (FFS) method. The morphology, structure and optical properties of the MWCNTs film were characterized by SEM and UV-Vis. spectra techniques. The SEM images reflected highly ordered network in the form of ropes or bundles with close-packing which looks like spaghetti. The absorbance spectrum revealed that the network has a good absorbance in the UV-Vis. region. The gas sensor system was used to test the MWCNT-OH network to detect NH3gas at room temperature. The resistance of the sensor was increased when exposed to the NH3gas. The sensitivities of the network were 1.3% at 14ppm, 3.3% at 27ppm and 6.13% at 68ppm. The sensor is specifically sensitive to NH3gas and does not affect by the amount of ambient air.

scholarly journals A Facile and Efficient Bromination of Multi-Walled Carbon Nanotubes

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3161
Author(s):  
Sandra Zarska ◽  
Damian Kulawik ◽  
Volodymyr Pavlyuk ◽  
Piotr Tomasik ◽  
Alicja Bachmatiuk ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Room Temperature ◽  
Covalent Attachment ◽  
Closed Vessel ◽  
Dangling Bonds ◽  
Magnetic Stirrer ◽  
Defect Sites ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Covalently Bound

The bromination of multi-walled carbon nanotubes (MWCNT) was performed with vapor bromine in a closed vessel, and they were subjected to intensive stirring with a magnetic stirrer for up to 14 days. The efficiency of bromination was compared depending upon duration. The structure and surface of the crude and purified products were characterized by detailed physicochemical analyses, such as SEM/EDS, TEM, XRD, TGA, Raman, and XPS spectroscopies. The studies confirmed the presence of bromine covalently bound with nanotubes as well as the formation of inclusion MWCNT–Br2 complexes. It was confirmed that Br2 molecules are absorbed on the surface of nanotubes (forming the CNT-Br2 complex), while they can dissociate close to dangling bonds at CNT defect sites with the formation of covalent C−Br bonds. Thus, any covalent attachment of bromine to the graphitic surface achieved around room temperature is likely related to the defects in the MWCNTs. The best results, i.e., the highest amount of attached Br2, were obtained for brominated nanotubes brominated for 10 days, with the content of covalently bound bromine being 0.68 at% (by XPS).

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