scholarly journals Adsorption Sites of Hydrogen Atom on Pure and Mg-Doped Multi-Walled Carbon Nanotubes

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
A. A. Al-Ghamdi ◽  
E. Shalaan ◽  
F. S. Al-Hazmi ◽  
Adel S. Faidah ◽  
S. Al-Heniti ◽  
...  
Keyword(s):  
Hydrogen Adsorption ◽  
Md Simulations ◽  
Material System ◽  
Magnesium Atom ◽  
Multiwalled Carbon ◽  
Adsorption Sites ◽  
Hydrogen Molecules ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Mg Doped

Hydrogen adsorption sites on pure multiwalled carbon nanotube (MWCNT) and Mg-doped MWCNTs material system have been investigated using molecular dynamics (MD) simulations as well as quantum chemical calculations. Through combining MWCNTs with Mg, the hydrogen adsorption sites energy on this Mg-MWCNTs system is found to be larger than that of the pure MWCNTs. Additionally, it was found that, through Mg-doping, new adsorption sites for hydrogen molecules are created in comparison with undoped nanotubes. It is also found that H atom is preferably adsorbed at every place near magnesium atom.

The Role of Metal Catalyst in Near Ambient Hydrogen Adsorption on Multi-walled Carbon Nanotubes

2004 ◽  
Vol 837 ◽  
Author(s):  
Yong-Won Lee ◽  
Rohit Deshpande ◽  
Anne C. Dillon ◽  
Michael J. Hebe ◽  
Hongjie Dai ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Adsorption ◽  
Chemical Vapor ◽  
Metal Catalyst ◽  
Ambient Conditions ◽  
Multiwalled Carbon ◽  
Multi Walled Carbon Nanotubes ◽  
Methane Source ◽  
Temperature Programmed ◽  
Walled Carbon Nanotubes

ABSTRACTMultiwalled carbon nanotubes (MWNTs) were continuously synthesized by hot wire chemical vapor deposition (HWCVD) using a methane source catalyzed by metal-organic ferrocene. The microstructure of the MWNTs and the catalyst particles were subsequently characterized with transmission electron microscopy which identified three different phases, i.e., bcc α-Fe, fcc γ-Fe and orthorhombic Fe3C. The hydrogen storage capacity of MWNTs was determined with temperature-programmed desorption (TPD) technique. Hydrogen adsorption at near ambient conditions was observed only in as-synthesized MWNTs containing iron particles and was dramatically increased after hydrogen reducing treatment. Possible adsorption mechanism was also discussed.

Determination of the Isosteric Heat of Adsorption of Hydrogen on the Multi-Walled Carbon Nanotubes

2012 ◽  
Vol 512-515 ◽  
pp. 1484-1491 ◽  
Author(s):  
Qing Rong Zheng ◽  
Shuai Gao ◽  
Chen Jie
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Adsorption ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Step Method ◽  
Surface Loading ◽  
Isosteric Heat Of Adsorption ◽  
Hydrogen Molecules ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The isosteric heat of adsorption was used to study the interaction between hydrogen molecules and the Multi-Walled Carbon Nanotubes (MWCNTs). Characterizations of the MWCNTs sample were carried out based on the N2 adsorption isotherm at 77 K and the images from TEM and HRTEM. Step by step method was used to volumetrically measure hydrogen adsorption isotherms at equilibrium temperature-pressures from 123-310 K and 0-12.3 MPa. Isosteric heats of adsorption at seven excess adsorption amounts and that at zero surface loading were respectively determined by the slopes of the adsorption isosteres and the plot of the temperature dependence of the Henry’s constants. Results show that the limit of the isosteric heat of adsorption at zero surface loading is about and the mean under the experimental condition is about . The values are in the same grade as those of hydrogen on the activated coconut charcoal but smaller than those of hydrogen on the graphitized carbon black P33, the activated carbon AX-21 and the Single-Walled Carbon Nanotubes (SWCNTs). Conclusions are drawn that relatively lower adsorption amounts and the isosteric heat of hydrogen adsorption on the MWCNTs could be ascribed to the small specific surface area and the large mesopores.

scholarly journals Understanding Covalent Grafting of Nanotubes onto Polymer Nanocomposites: Molecular Dynamics Simulation Study

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2621
Author(s):  
Seunghwa Yang
Keyword(s):  
Molecular Dynamics ◽  
Load Transfer ◽  
Cell Model ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Covalent Grafting ◽  
Modelling Strategies ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
External Loads

Here, we systematically interrogate the effects of grafting single-walled (SWNT) and multi-walled carbon nanotubes (MWNT) to polymer matrices by using molecular dynamics (MD) simulations. We specifically investigate key material properties that include interfacial load transfer, alteration of nanotube properties, and dispersion of nanotubes in the polymer matrix. Simulations are conducted on a periodic unit cell model of the nanocomposite with a straight carbon nanotube and an amorphous polyethylene terephthalate (PET) matrix. For each type of nanotube, either 0%, 1.55%, or 3.1% of the carbon atoms in the outermost nanotubes are covalently grafted onto the carbon atoms of the PET matrix. Stress-strain curves and the elastic moduli of nanotubes and nanocomposites are determined based on the density of covalent grafting. Covalent grafting promotes two rivalling effects with respect to altering nanotube properties, and improvements in interfacial load transfer in the nanocomposites are clearly observed. The enhanced interface enables external loads applied to the nanocomposites to be efficiently transferred to the grafted nanotubes. Covalent functionalization of the nanotube surface with PET molecules can alter the solubility of nanotubes and improve dispersibility. Finally, we discuss the current limitations and challenges in using molecular modelling strategies to accurately predict properties on the nanotube and polymers systems studied here.

Investigation, using density function theory, of coverage of the kaolinite (001) surface during hydrogen adsorption

Clay Minerals ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 393-402 ◽  
Author(s):  
Jian Zhao ◽  
Wei Gao ◽  
Zhi-Gang Tao ◽  
Hong-Yun Guo ◽  
Man-Chao He
Keyword(s):  
Density Functional ◽  
Hydrogen Adsorption ◽  
Function Theory ◽  
Lattice Relaxation ◽  
Electronic Density ◽  
Functional Theory ◽  
Adsorption Sites ◽  
Coverage Dependence ◽  
Hydrogen Molecules ◽  
Wide Range

ABSTRACTKaolinite can be used for many applications, including the underground storage of gases. Density functional theory was employed to investigate the adsorption of hydrogen molecules on the kaolinite (001) surface. The coverage dependence of the adsorption sites and energetics was studied systematically for a wide range of coverage, Θ (from 1/16 to 1 monolayer). The three-fold hollow site is the most stable, followed by the bridge, top-z and top sites. The adsorption energy of H2 decreased with increasing coverage, thus indicating the lower stability of surface adsorption due to the repulsion of neighbouring H2 molecules. The coverage has obvious effects on hydrogen adsorption. Other properties of the H2/kaolinite (001) system, including the lattice relaxation and changes of electronic density of states, were also studied and are discussed in detail.

Characterization of Mechanical and Viscoelastic Properties of SC-15 Epoxy Nanocomposites Reinforced With Multi-Walled Carbon Nanotubes, Nanoclay and Binary Nanoparticles

2014 ◽  
Author(s):  
Tanjheel H. Mahdi ◽  
Mohammad E. Islam ◽  
Mahesh V. Hosur ◽  
Alfred Tcherbi-Narteh ◽  
S. Jeelani
Keyword(s):  
Carbon Nanotubes ◽  
Epoxy Resin ◽  
Viscoelastic Properties ◽  
Flexural Modulus ◽  
Epoxy Nanocomposites ◽  
Multiwalled Carbon ◽  
Epoxy Resin System ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Binary Nanoparticles

Mechanical and viscoelastic properties of polymer nanocomposites reinforced with carboxyl functionalized multiwalled carbon nanotubes (COOH-MWCNT), montmorillonite nanoclays (MMT) and MWCNT/MMT binary nanoparticle were investigated. In this study, 0.3 wt. % of COOH-MWCNT, 2 wt. % of MMT and 0.1 wt. % COOH-MWCNT/2 wt. % MMT binary nanoparticles by weight of epoxy were incorporated to modify SC-15 epoxy resin system. The nanocomposites were subjected to flexure test, dynamic mechanical and thermomechanical analyses. Morphological study was conducted with scanning electron microscope. Addition of each of the nanoparticles in epoxy showed significant improvement in mechanical and viscoelastic properties compared to those of control ones. But, best results were obtained for addition of 0.1% MWCNT/2% MMT binary nanoparticles in epoxy. Nanocomposites modified with binary nanoparticles exhibited about 20% increase in storage modulus as well as 25° C increase in glass transition temperature. Flexural modulus for binary nanoparticle modified composites depicted about 30% improvement compared to control ones. Thus, improvement of mechanical and viscoelastic properties was achieved by incorporating binary nanoparticles to epoxy nanocomposites. The increase in properties was attributed to synergistic effect of MWCNTs and nanoclay in chemically interacting with each other and epoxy resin as well as in arresting and delaying the crack growth once initiated.

scholarly journals Theoretical Study on the Adsorbed Hydrogen Molecules on Multi-Walled Carbon Nanotubes

2003 ◽  
Vol 19 (02) ◽  
pp. 139-143
Author(s):  
Zheng Qing-Rong ◽  
◽  
Gu An-Zhong ◽  
Lin Wen-Sheng ◽  
Li Ming ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Theoretical Study ◽  
Adsorbed Hydrogen ◽  
Hydrogen Molecules ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Hydrogen adsorption/desorption behavior of multi-walled carbon nanotubes with different diameters

Carbon ◽  
2003 ◽  
Vol 41 (13) ◽  
pp. 2471-2476 ◽  
Author(s):  
Peng-Xiang Hou ◽  
Shi-Tao Xu ◽  
Zhe Ying ◽  
Quan-Hong Yang ◽  
C. Liu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Adsorption ◽  
Multi Walled Carbon Nanotubes ◽  
Different Diameters ◽  
Adsorption Desorption ◽  
Walled Carbon Nanotubes

scholarly journals Enhancement photocatalytic activity of spinel oxide (Co, Ni)3O4 by combination with carbon nanotubes

2017 ◽  
Vol 19 (3) ◽  
pp. 61-67 ◽  
Author(s):  
Bashaer J. Kahdum ◽  
Abbas J. Lafta ◽  
Amir M. Johdh
Keyword(s):  
Carbon Nanotubes ◽  
Photocatalytic Activity ◽  
Diffuse Reflectance Spectroscopy ◽  
X Rays ◽  
Spinel Oxide ◽  
Reaction Conditions ◽  
Multiwalled Carbon ◽  
Radiation Sources ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Abstract In this study, some types of composites consisting of multi-walled carbon nanotubes (MWCNTs) and spinel oxide (Co, Ni)3O4 were synthesized by simple evaporation method. These composites were characterized by UV–Vis diffuse reflectance spectroscopy, X-rays diffraction(XRD), Scanning electron microscopy (SEM) and specific surface area(SBET). The photocatalytic activity of the prepared composites was investigated by the following removal of Bismarck brown G (BBG) dye from its aqueous solutions. The obtained results showed that using MWCNTs in combination with spinel oxide to produced composites (spinel/MWCNTs) which succeeded in increasing the activity of spinel oxide and exhibited higher photocatalytic activity than spinel oxide alone. Also it was found that, multiwalled carbon nanotubes were successful in increasing the adsorption and improving the activity of photocatalytic degradation of Bismarck brown G dye(BBG). The obtained results showed that spinel/MWCNTs was more active in dye removal in comparison with each of spinel oxide and MWCNTs alone under the same reaction conditions. Also band gap energies for the prepared composites showed lower values in comparison with neat spinel. This point represents a promising observation as these composites can be excited using a lower energy radiation sources.

Tribological Properties of Stearic Acid Modified Multi-Walled Carbon Nanotubes in Water

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Yitian Peng ◽  
Zhonghua Ni
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Stearic Acid ◽  
Tribological Properties ◽  
Friction Reduction ◽  
Multiwalled Carbon ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Lubricant Application ◽  
Walled Carbon Nanotubes

The oxidized multiwalled carbon nanotubes (MWCNTs) were modified with stearic acid (SA) molecules. The SA-modified MWCNTs were characterized with scanning electron microscopy, transmission electron microscopy, and Fourier transform-infrared spectroscopy. The tribological properties of the oxidized and SA-modified MWCNTs as additives in water were comparatively investigated with a four-ball tester. The results showed the SA-modified MWCNTs in water have better tribological properties including friction reduction and antiwear than oxidized MWCNTs. The possible mechanism of SA-modified MWCNT as an additive in water was discussed. This research provides the opportunity for the lubricant application of MWCNTs.

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