scholarly journals Temperature Dependence of Sensors Based on Silver-Decorated Nitrogen-Doped Multiwalled Carbon Nanotubes

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Eduardo Gracia-Espino ◽  
Bernabé Rebollo-Plata ◽  
Hugo Martínez-Gutiérrez ◽  
Emilio Muñoz-Sandoval ◽  
Florentino López-Urías ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Density Functional ◽  
Chemical Vapor ◽  
Ag Nps ◽  
Multiwalled Carbon ◽  
Detection Mechanism ◽  
Nitrogen Doped ◽  
Vapor Sensors

Vapor sensors are easily fabricated onto alumina substrates using foils of silver-decorated nitrogen-doped multiwalled carbon nanotubes (CNX-MWNTs-Ag) as active sensing material. The vapor sensors are tested using carbon disulfide, acetone, ethanol, and chloroform vapors. The CNX-MWNTs are produced by chemical vapor deposition process and then decorated with 14 nm Ag nanoparticles (Ag-NPs). The samples are characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Our results demonstrate that Ag-decorated CNX-MWNTs exhibit a better response and sensitivity when compared with pristine CNX-MWNTs based sensors, making them promising candidates for air-pollutants environmental monitoring. The temperature effect on the sensor performance is also studied; we found that the detection mechanism could be tuned from physisorption, at room temperature, to chemisorption at higher working temperature. Finally, first-principles density functional calculations are carried out to understand the interactions between the systems involved in the sensors, finding good agreement between experimental results and the theoretical approach.

scholarly journals Bromate Removal from Water Using Doped Iron Nanoparticles on Multiwalled Carbon Nanotubes (CNTS)

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Aasem Zeino ◽  
Abdalla Abulkibash ◽  
Mazen Khaled ◽  
Muataz Atieh
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Adsorption Capacity ◽  
Multiwalled Carbon Nanotubes ◽  
Iron Nanoparticles ◽  
Chemical Vapor ◽  
Chemical Vapor Deposition Method ◽  
Scanning Calorimetry ◽  
Multiwalled Carbon ◽  
Transmission Electron

The raw carbon nanotubes (CNTs) were prepared by the floating catalyst chemical vapor deposition method. The raw carbon nanotubes were functionalized, impregnated with iron nanoparticles, and characterized using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and thermogravimetric analysis (TGA). The three types of these multiwalled carbon nanotubes were applied as adsorbents for the removal of bromate from drinking water. The effects of the pH, the concentration ofBrO3-anion, the adsorbent dose, the contact time, and the coanions on the adsorption process have been investigated. The results concluded that the highest adsorption capacities were 0.3460 and 0.3220 mg/g through using CNTs-Fe and raw CNTs, respectively, at the same conditions. The results showed that the CNTs-Fe gives higher adsorption capacity compared with the raw CNTs and the functionalized CNTs. The presence of nitrate (NO3-) in the solution decreases the adsorption capacity of all CNTs compared with chloride (Cl-) associated with pH adjustment caused by nitric acid or hydrochloric acid, respectively. However, the adsorption of all MWNCTs types increases as the pH of solution decreases.

scholarly journals Cement Pastes and Mortars Containing Nitrogen-Doped and Oxygen-Functionalized Multiwalled Carbon Nanotubes

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Mauricio Martínez-Alanis ◽  
Florentino López-Urías
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Multiwalled Carbon Nanotubes ◽  
Density Functional ◽  
Multiwalled Carbon ◽  
Cement Pastes ◽  
Hydrated Calcium Silicate ◽  
Nitrogen Doped ◽  
Cementitious Matrix ◽  
Functionalized Multiwalled Carbon Nanotubes

Cement pastes and mortars based on ordinary Portland cement containing nitrogen-doped multiwalled carbon nanotubes (MWCNT-Nx) or oxygen-functionalized multiwalled carbon nanotubes (MWCNT-Ox) are investigated. To incorporate MWCNTs into the cementitious matrix, the as-produced carpets are dispersed over periods of 1 and 2 hours in distilled water at pH levels of 1 and 7. The cement pastes are prepared by adding 0.1 wt% of MWCNTs to cement powder, followed by characterization with SEM and X-ray diffraction (XRD) at an early age (first hours of hydration). The mortars are mechanically characterized during the hydration process for a period of 28 days. SEM characterization of cement pastes revealed that the carbon nanotubes are well incorporated in the cementitious matrix, with the hydrated cement grains interconnected by long carbon nanotubes. XRD characterizations demonstrated that, during the hydration of cement pastes, different peaks emerged that were associated with ettringite, hydrated calcium silicate, and calcium hydroxide, among other structures. Results of the compressive strength measurements for mortars simultaneously mixed with MWCNT-Nx and MWCNT-Ox reached an increment of approximately 30% in compressive strength. In addition, density functional theory calculations were performed in nitrogen-doped and oxygen-functionalized carbon nanotubes interacting with a cement grain.

Composites of Polyvinyl Alcohol and Carbon (Coils, Undoped and Nitrogen Doped Multiwalled Carbon Nanotubes) as Ethanol, Methanol and Toluene Vapor Sensors

2011 ◽  
Vol 11 (11) ◽  
pp. 10211-10218 ◽  
Author(s):  
Márcia W. C. C. Greenshields ◽  
Ivo A. Hümmelgen ◽  
Messai A. Mamo ◽  
Ahmed Shaikjee ◽  
Sabelo D. Mhlanga ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Polyvinyl Alcohol ◽  
Multiwalled Carbon Nanotubes ◽  
Multiwalled Carbon ◽  
Nitrogen Doped ◽  
Toluene Vapor ◽  
Vapor Sensors

Technology of Fabrication and Morphology of Multiwalled Carbon Nanotubes on Co-Ni/MgO Catalysts by Thermal CVD

2009 ◽  
Vol 4 ◽  
pp. 45-64 ◽  
Author(s):  
Ho Jin Ryu ◽  
B.K. Singh ◽  
K.S. Bartwal ◽  
Iwan V. Kityk
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Maximum Yield ◽  
Chemical Vapor ◽  
Linear Structure ◽  
Multiwalled Carbon ◽  
Co Catalyst ◽  
Carbon Particles ◽  
Transmission Electron

Multiwalled carbon nanotubes (MWNTs) were fabricated by thermal chemical vapor deposition (CVD) using monometallic and bimetallic Co and Ni on MgO as the catalyst. The mixture of H2/C2H2 gas was used as carbon source. The prepared CNTs have different sizes/shapes and morphologies with minimal formation of carbon particles. The maximum yield of CNTs was obtained with 50% Co catalyst at 600 oC. The morphology of the CNTs with 50% Co loading generates curved structure while 50% Ni results in the formation of linear structure with aligned graphene walls. Intensity ratio of D and G-peaks (ID/IG) was measured from Raman spectra. Scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) was done for the structural analysis of the prepared MWNTs.

scholarly journals Decoration of Silver Nanoparticles on Multiwalled Carbon Nanotubes: Antibacterial Mechanism and Ultrastructural Analysis

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Ngo Xuan Dinh ◽  
Nguyen Van Quy ◽  
Tran Quang Huy ◽  
Anh-Tuan Le
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Silver Nanoparticles ◽  
Cell Membrane ◽  
Multiwalled Carbon Nanotubes ◽  
Ultrastructural Changes ◽  
Physical Interaction ◽  
Ag Nps ◽  
Multiwalled Carbon ◽  
Membrane Function

Recently, development of carbon nanocomposites composed of carbon nanostructures and metal nanoparticles has attracted much interests because of their large potential for technological applications such as catalyst, sensor, biomedicine, and disinfection. In this work, we established a simple chemistry method to synthesize multiwalled carbon nanotubes (MWCNTs) decorated with silver nanoparticles (Ag-NPs) using a modified photochemical reaction (Tollens process). The formation and interaction of Ag-NPs with functionalized groups on the surface of MWCNTs were analyzed by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The average size of Ag-NPs on the MWCNTs was approximately ~7 nm with nearly uniform size distribution. Antibacterial effect of Ag-MWCNTs nanocomposites was evaluated against two pathogenic bacteria including Gram-negativeEscherichia Coliand Gram-positiveStaphylococcus aureusbacteria. Interaction and bactericidal mechanism of Ag-MWCNTs with tested bacteria was studied by adapting the electron microscopy. Analysis on ultrastructural changes of bacterial cells indicates that antibacterial action mechanism of Ag-MWCNTs is physical interaction with cell membrane, the large formation of cell-Ag-MWCNTs aggregates, and faster destructibility of cell membrane and disruption of membrane function, hence resulting in cells death.

SILK FIBROIN FILMS CRYSTALLIZED BY MULTIWALLED CARBON NANOTUBES

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1807-1812 ◽  
Author(s):  
H.-S. KIM ◽  
W.-I. PARK ◽  
Y. KIM ◽  
H.-J. JIN
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Silk Fibroin ◽  
Composite Films ◽  
Tensile Modulus ◽  
Multiwalled Carbon ◽  
Regenerated Silk Fibroin ◽  
Silk Films ◽  
Β Sheet

Silk films prepared from regenerated silk fibroin are normally stabilized by β-sheet formation through the use of solvents (methanol, water etc.). Herein, we report a new method of preparing water-stable films without a β-sheet conformation from regenerated silk fibroin solutions by incorporating a small amount (0.2 wt%) of multiwalled carbon nanotubes (MWCNTs). To extend the biomaterial utility of silk proteins, forming water-stable silk-based materials with enhanced mechanical properties is essential. Scanning electron microscopy and transmission electron microscopy were used to observe the morphology of the MWCNT-incorporated silk films. The wide-angle X-ray diffraction provided clear evidence of the crystallization of the silk fibroin induced by MWCNT in the composite films without any additional annealing processing. The tensile modulus and strength of the composite films were improved by 108% and 51%, respectively, by the incorporation of 0.2 wt% of MWCNTs, as compared with those of the pure silk films. The method described in this study will provide an alternative means of crystallizing silk fibroin films without using an organic solvent or blending with any other polymers, which may be important in biomedical applications.

Multiwalled Carbon Nanotubes by Chemical Vapor Deposition Using Multilayered Metal Catalysts

2002 ◽  
Vol 106 (22) ◽  
pp. 5629-5635 ◽  
Author(s):  
Lance Delzeit ◽  
Cattien V. Nguyen ◽  
Bin Chen ◽  
Ramsey Stevens ◽  
Alan Cassell ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Multiwalled Carbon Nanotubes ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Metal Catalysts ◽  
Multiwalled Carbon

scholarly journals Surface Properties of Silica–MWCNTs/PDMS Composite Coatings Deposited on Plasma Activated Glass Supports

2021 ◽  
Vol 11 (19) ◽  
pp. 9256
Author(s):  
Michał Chodkowski ◽  
Iryna Ya. Sulym ◽  
Konrad Terpiłowski ◽  
Dariusz Sternik
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Scanning Electron Microscopy ◽  
Multiwalled Carbon Nanotubes ◽  
Composite Coatings ◽  
Thermal Analyses ◽  
Sol Gel ◽  
Visible Range ◽  
Multiwalled Carbon ◽  
Scanning Electron

In this paper, we focus on fabrication and physicochemical properties investigations of silica–multiwalled carbon nanotubes/poly(dimethylsiloxane) composite coatings deposited on the glass supports activated by cold plasma. Air or argon was used as the carrier gas in the plasma process. Multiwalled carbon nanotubes were modified with poly(dimethylsiloxane) in order to impart their hydrophobicity. The silica–multiwalled carbon nanotubes/poly(dimethylsiloxane) nanocomposite was synthesized using the sol–gel technique with acid-assisted tetraethyl orthosilicate hydrolysis. The stability and the zeta potential of the obtained suspension were evaluated. Then, the product was dried and used as a filler in another sol–gel process, which led to the coating application via the dip-coating method. The substrates were exposed to the hexamethyldisilazane vapors in order to improve their hydrophobicity. The obtained surfaces were characterized by the wettability measurements and surface free energy determination as well as optical profilometry, scanning electron microscopy, and transmittance measurements. In addition, the thermal analyses of the carbon nanotubes as well as coatings were made. It was found that rough and hydrophobic coatings were obtained with a high transmittance in the visible range. They are characterized by the water contact angle larger than 90 degrees and the transmission at the level of 95%. The X-ray diffraction studies as well as scanning electron microscopy images confirmed the chemical and structural compositions of the coatings. They are thermally stable at the temperature up to 250 °C. Moreover, the thermal analysis showed that the obtained composite material has greater thermal resistance than the pure nanotubes.

Covalent functionalization of multiwalled carbon nanotubes with super-hydrophobic property

2018 ◽  
Vol 38 (6) ◽  
pp. 537-543 ◽  
Author(s):  
Minghua Li ◽  
Zhiyuan Xu ◽  
Jinyang Chen ◽  
San-E Zhu
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Chemical Interaction ◽  
Hydrophobic Property ◽  
Covalent Functionalization ◽  
Multiwalled Carbon ◽  
Surface Contact Angle ◽  
Loading Ratio ◽  
Functionalized Mwcnts

AbstractSurface covalent functionalization of multiwalled carbon nanotubes (MWCNTs) is carried out by coupling of isocyanate-decorated MWCNTs with hydroxyl-terminated polydimethylsiloxane (HTPS), resulting in the formation of functionalized MWCNTs. Thermogravimetry analysis (TGA) of functionalized MWCNTs-1,2,3 exhibits the similar peaks in the temperature range of 200–500°C, which all correspond to the degradation of chemically grafted polyurethane on the nanotube surface. Field emission scanning electron microscopy (FE-SEM) reveals that as the polyurethane grafted onto the surface of MWCNTs loading ratio increased, the surface roughness of the MWCNTs is reduced. The chemical interaction of HTPS with isocyanate-decorated nanotube surface using the grafting-to strategy in a one-step process is confirmed by Fourier transform infrared spectroscopy (FT-IR). The surface contact angle of MWCNTs-3 with the largest content of polyurethane reached 171°, indicating that the surface covered with low surface energy polyurethane shows a super-hydrophobic property. The good dispersion of polyurethane-functionalized MWCNT-3, particularly at high content in the NR nanocomposites, is evidenced from transmission electron microscopy (TEM).

Carbon sponge-type nanostructures based on coaxial nitrogen-doped multiwalled carbon nanotubes grown by CVD using benzylamine as precursor

Carbon ◽  
2017 ◽  
Vol 115 ◽  
pp. 409-421 ◽  
Author(s):  
Emilio Muñoz-Sandoval ◽  
Alejandro J. Cortes-López ◽  
Beatriz Flores-Gómez ◽  
Juan L. Fajardo-Díaz ◽  
Roque Sánchez-Salas ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Multiwalled Carbon ◽  
Nitrogen Doped
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