scholarly journals The Role of Temperature on the Degree of End-Closing and Filling of Single-Walled Carbon Nanotubes

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3365
Author(s):  
Magdalena Kierkowicz ◽  
Elzbieta Pach ◽  
Julio Fraile ◽  
Concepción Domingo ◽  
Belén Ballesteros ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Surface Area ◽  
Density Functional ◽  
Annealing Temperature ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Density Functional Theory Calculations ◽  
Nitrogen Adsorption

Carbon nanotubes (CNTs), owing to their high surface area-to-volume ratio and hollow core, can be employed as hosts for adsorbed and/or encapsulated molecules. At high temperatures, the ends of CNTs close spontaneously, which is relevant for several applications, including catalysis, gas storage, and biomedical imaging and therapy. This study highlights the influence of the annealing temperature in the range between 400 and 1100 °C on the structure and morphology of single-walled CNTs. The nitrogen adsorption and density functional theory calculations indicate that the fraction of end-closed CNTs increases with temperature. Raman spectroscopy reveals that the thermal treatment does not alter the tubular structure. Insight is also provided into the efficacy of CNTs filling from the molten phase, depending on the annealing temperature. The CNTs are filled with europium (III) chloride and analyzed by using electron microscopy (scanning electron microscopy and high-resolution transmission electron microscopy) and energy-dispersive X-ray spectroscopy, confirming the presence of filling and closed ends. The filling yield increases with temperature, as determined by thermogravimetric analysis. The obtained results show that the apparent surface area of CNTs, fraction of closed ends, and amount of encapsulated payload can be tailored via annealing.

scholarly journals Synthesis and characterization of porous silica and polyaniline-porous silica composite materials with high surface area

2014 ◽  
Vol 49 (1) ◽  
pp. 1-8
Author(s):  
US Akhtar ◽  
MK Hossain ◽  
MS Miran ◽  
MYA Mollah
Keyword(s):  
Electron Microscopy ◽  
Pore Size ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Porous Silica ◽  
Nitrogen Adsorption ◽  
High Specific Surface Area ◽  
Molar Ratio ◽  
Cylindrical Pore

Porous silica materials were synthesized from tetraethyl orthosilicate (TEOS) using Pluronic P123 (non-ionic triblock copolymer, EO20PO70O20) as template under acidic conditions which was then used to prepare polyaniline (PAni) and porous silica composites (PAnisilica) at a fixed molar ratio. These materials were characterized by nitrogen adsorption-desorption isotherm measured by Barrett-Joyner- Halenda (BJH) method and pore size distribution from desorption branch and surface area measured by the Brunauer-Emmett-Teller (BET) method, scanning electron microscopy (SEM), transmission electron microscopy (TEM), TEM-energy dispersive X-ray (EDX) and Fourier transform infrared (FT-IR) spectroscopy. The composite maintains its structure even after the polymerization and the polymer is dispersed on the inorganic matrix. The rod-like porous silica was about 1?m to 1.5 ?m long and on an average the diameter was in the range of 300- 500 nm. The SEM and TEM images show well ordered 2d hexagonal pore, high specific surface area (850 m2g-1) and uniform pore size of ca. 6.5 nm in diameter. After incorporation of PAni inside the silica pore, framework of porous silica did not collapse and the surface area of the composite was as high as 434 m2g-1 which was 5.5 time higher than our previous report of 78.3 m2g-1. Due to shrinkage of the framework during the incorporation of aniline inside the silica, the pore diameter slightly increase to 7.5 nm but still showing Type IV isotherm and typical hysteresis loop H1 implying a uniform cylindrical pore geometry. DOI: http://dx.doi.org/10.3329/bjsir.v49i1.18847 Bangladesh J. Sci. Ind. Res. 49(1), 1-8, 2014

Growth of Carbon Nanotubes on Carbon Toray Paper for Bio-Fuel Cell Applications

2007 ◽  
Author(s):  
Bhupesh Chandra ◽  
Joshua T. Kace ◽  
Yuhao Sun ◽  
S. C. Barton ◽  
James Hone
Keyword(s):  
Carbon Nanotubes ◽  
Fuel Cell ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Multiwall Carbon Nanotubes ◽  
Volume Ratio ◽  
Carbon Paper ◽  
Heating Process ◽  
Scale Production

In recent years carbon nanotubes have emerged as excellent materials for applications in which high surface area is required e.g. gas sensing, hydrogen storage, solar cells etc. Ultra-high surface to volume ratio is also a desirable property in the applications requiring enhanced catalytic activity where these high surface area materials can act as catalyst supports. One of the fastest developing areas needing such materials is fuel-cell. Here we investigate the process through which carbon nanotubes can be manufactured specifically to be used to increase the surface area of a carbon paper (Toray™). This carbon support is used in bio-catalytic fuel cell as an electrode to support enzyme which catalyzes the redox reaction. Deposition of nanotubes on these carbon fibers can result in great enhancement in the overall surface area to support the enzyme, which increases the reaction rate inside the fuel cell. The present paper describes a method to achieve ultra-thick growth of multiwall carbon nanotubes (MWNT) on a carbon Toray™ paper using a joule heating process and gas-phase catalyst. Using this method, we are able to achieve rapid, high-density, and uniform MWNT growth. This method is also potentially scalable toward larger-scale production.

scholarly journals Metal-Free Counter Electrode for Efficient Dye-Sensitized Solar Cells through High Surface Area and Large Porous Carbon

2011 ◽  
Vol 2011 ◽  
pp. 1-4 ◽  
Author(s):  
Pavuluri Srinivasu ◽  
Surya Prakash Singh ◽  
Ashraful Islam ◽  
Liyuan Han
Keyword(s):  
Electron Microscopy ◽  
Surface Area ◽  
Mesoporous Carbon ◽  
Counter Electrode ◽  
High Surface ◽  
High Surface Area ◽  
Dye Sensitized Solar Cells ◽  
Nitrogen Adsorption ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Highly efficient, large mesoporous carbon is fabricated as a metal-free counter electrode for dye-sensitized solar cells. The mesoporous carbon shows very high energy conversion efficiency of 7.1% compared with activated carbon. The mesoporous carbon is prepared and characterized by nitrogen adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The nitrogen adsorption data reveals that the material possesses BET specific surface area ca.1300 m2/g and pore diameter 4.4 nm. Hexagonal rod-like morphology and ordered pore structure of mesoporous carbon are confirmed by electron microscopy data. The better performance of this carbon material is greatly benefited from its ordered interconnected mesoporous structure and high surface area.

scholarly journals Green Synthesis of S- and N-Codoped Carbon Nanospheres and Application as Adsorbent of Pb (II) from Aqueous Solution

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Nadia Hussain ◽  
Salam Alwan ◽  
Hassan Alshamsi ◽  
Ibrahim Sahib
Keyword(s):  
Electron Microscopy ◽  
Surface Area ◽  
Adsorption Process ◽  
High Surface ◽  
High Surface Area ◽  
Correlation Coefficients ◽  
Nitrogen Adsorption ◽  
Entropy Change ◽  
Standard Entropy ◽  
Carbon Nanospheres

In this paper, green and facile synthesis of sulfur- and nitrogen-codoped carbon nanospheres (CNs) was prepared from the extract of Hibiscus sabdariffa L by a direct hydrothermal method. Finally, sulfur-carbon nanospheres (CNs) were used as the adsorbent to remove Pb+2 ions from aqueous solutions because of the high surface area of S-CNs from CNs and N-CNs. The synthesized nanospheres were examined by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy, transmission electron microscopy (TEM), and nitrogen adsorption-desorption isotherms. The results show spherical shapes have a particle size of up to 65 nm with a high surface area capable of absorbing lead ions efficiently. Additionally, the factors affecting the process of adsorption that include equilibrium time, temperature, pH solution, ionic intensity, and adsorbent dose were studied. The equilibrium removal efficiency was studied employing Langmuir, Freundlich, and Temkin isotherm forms. The kinetic data were analyzed with two different kinetic models, and both apply to the adsorption process depending on the values of correlation coefficients. The thermodynamic parameters including Gibbs free energy (ΔG°), standard enthalpy change (ΔH°), and standard entropy change (ΔS°) were calculated for the adsorption process.

Texture Evaluation of Sol-Gel Derived Mesoporous Bioactive Glass

2013 ◽  
Vol 284-287 ◽  
pp. 230-234
Author(s):  
Yu Jen Chou ◽  
Chi Jen Shih ◽  
Shao Ju Shih
Keyword(s):  
Surface Area ◽  
Calcination Temperature ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Bioactive Glasses ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Adsorption Desorption

Recent years mesoporous bioactive glasses (MBGs) have become important biomaterials because of their high surface area and the superior bioactivity. Various studies have reported that when MBGs implanted in a human body, hydroxyl apatite layers, constituting the main inorganic components of human bones, will form on the MBG surfaces to increase the bioactivity. Therefore, MBGs have been widely applied in the fields of tissue regeneration and drug delivery. The sol-gel process has replaced the conventional glasses process for MBG synthesis because of the advantages of low contamination, chemical flexibility and lower calcination temperature. In the sol-gel process, several types of surfactants were mixed with MBG precursor solutions to generate micelle structures. Afterwards, these micelles decompose to form porous structures after calcination. Although calcination is significant for contamination, crystalline and surface area in MBG, to the best of the authors’ knowledge, only few systematic studies related to calcination were reported. This study correlated the calcination parameters and the microstructure of MBGs. Microstructure evaluation was characterized by transmission electron microscopy and nitrogen adsorption/desorption. The experimental results show that the surface area and the pore size of MBGs decreased with the increasing of the calcination temperature, and decreased dramatically at 800°C due to the formation of crystalline phases.

scholarly journals Electrochemical Sensor Based on Prussian Blue Electrochemically Deposited at ZrO2 Doped Carbon Nanotubes Glassy Carbon Modified Electrode

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1328 ◽  
Author(s):  
Marlon Danny Jerez-Masaquiza ◽  
Lenys Fernández ◽  
Gema González ◽  
Marjorie Montero-Jiménez ◽  
Patricio J. Espinoza-Montero
Keyword(s):  
Carbon Nanotubes ◽  
Electrochemical Properties ◽  
Electrochemical Sensor ◽  
Prussian Blue ◽  
Surface Area ◽  
Glassy Carbon ◽  
High Surface ◽  
High Surface Area ◽  
Electrochemically Deposited ◽  
Area X

In this work, a new hydrogen peroxide (H2O2) electrochemical sensor was fabricated. Prussian blue (PB) was electrodeposited on a glassy carbon (GC) electrode modified with zirconia doped functionalized carbon nanotubes (ZrO2-fCNTs), (PB/ZrO2-fCNTs/GC). The morphology and structure of the nanostructured system were characterized by scanning and transmission electron microscopy (TEM), atomic force microscopy (AFM), specific surface area, X-ray diffraction (XRD), thermogravimetric analysis (TGA), Raman and Fourier transform infrared (FTIR) spectroscopy. The electrochemical properties were studied by cyclic voltammetry (CV) and chronoamperometry (CA). Zirconia nanocrystallites (6.6 ± 1.8 nm) with cubic crystal structure were directly synthesized on the fCNTs walls, obtaining a well dispersed distribution with a high surface area. The experimental results indicate that the ZrO2-fCNTs nanostructured system exhibits good electrochemical properties and could be tunable by enhancing the modification conditions and method of synthesis. The fabricated sensor could be used to efficiently detect H2O2, presenting a good linear relationship between the H2O2 concentration and the peak current, with quantification limit (LQ) of the 10.91 μmol·L−1 and detection limit (LD) of 3.5913 μmol·L−1.

scholarly journals Preparation and Characteristics of SiOx Coated Carbon Nanotubes with High Surface Area

Nanomaterials ◽  
2012 ◽  
Vol 2 (2) ◽  
pp. 206-216 ◽  
Author(s):  
Aeran Kim ◽  
Seongyop Lim ◽  
Dong-Hyun Peck ◽  
Sang-Kyung Kim ◽  
Byungrok Lee ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Coated Carbon
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