Preparation of Large Carbon Nanofibers on a Stainless Steel Surface and Elucidation of their Growth Mechanisms

2019 ◽  
Vol 74 (3) ◽  
pp. 253-258
Author(s):  
M. R. Elamin ◽  
Kamal K. Taha ◽  
Babiker Y. Abdulkhair ◽  
L. Khezami
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanofibers ◽  
Steel Substrate ◽  
Chemical Vapour ◽  
Nitrogen Adsorption ◽  
Average Diameter ◽  
Bet Surface Area ◽  
Stainless Steel Surface ◽  
Adsorption Analysis ◽  
Steel Substrates

AbstractIn this work different shapes of carbon nanofibers (CNFs) were successfully synthesised on a treated commercial steel substrate by catalytic chemical vapour deposition (CCVD) utilising ethanol at 700 °C. The formation of the nanofibers with average diameter of 200–400 nm was confirmed via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The BET surface area, pore volume and pore size of the obtained CNFs were sequentially: 182 m2/g, 10.5 cm3/g and 103.3 Å as determined by nitrogen adsorption analysis. The influence of the surface treatment on the size and shape of CNFs was investigated and the results indicated a positive correlation that can be employed to tailor CNFs of desired morphology. Accordingly, a growth mechanism due to the deposition of carbonaceous materials on large size nanoparticles was proposed. As the CCVD is a facile and economical route for CNFs synthesis, thus, it can be efficiently adopted for the growth of CNFs on pretreated steel substrates as proved by this study.

Effect of Urea on the Shape and Structure of Carbon Nanotubes

2018 ◽  
Vol 73 (2) ◽  
pp. 113-120 ◽  
Author(s):  
M. R. Elamin ◽  
Babiker Y. Abdulkhair ◽  
Kamal K. Taha
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Chemical Vapour ◽  
Multiwall Carbon Nanotubes ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Adsorption Analysis ◽  
Bet Analysis ◽  
Multiwall Carbon

AbstractCoiled multiwall carbon nanotubes (MWCNTs) were prepared on Fe, Co, and Ni metal oxides supported on α-Al2O3 using urea as fuel and catalyst surface modifying agent by catalytic chemical vapour deposition (CCVD). The shape of the nanotubes was influenced by the addition of urea, where coiled and uncoiled tubes were obtained in the presence and absence of urea, respectively. The MWCNTs were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption analysis. The coiling/uncoiling of the nanotubes was visualized from the SEM and TEM images of the prepared specimens. The XRD data showed the characteristic peaks of the nanotubes. BET analysis of the coiled tubes revealed 85.57 m2 g−1 surface area with a pore diameter 102.2–110.8 Å. A mechanism for the nanotubes coiling is suggested.

scholarly journals Preparation of Zirconia Nanofibers by Electrospinning and Calcination with Zirconium Acetylacetonate as Precursor

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1067 ◽  
Author(s):  
Vyacheslav V. Rodaev ◽  
Svetlana S. Razlivalova ◽  
Andrey O. Zhigachev ◽  
Vladimir M. Vasyukov ◽  
Yuri I. Golovin
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Heterogeneous Catalysts ◽  
Tetragonal Zirconia ◽  
Nitrogen Adsorption ◽  
Average Diameter ◽  
High Specific Surface Area ◽  
X Ray ◽  
Adsorption Analysis

For the first time, zirconia nanofibers with an average diameter of about 75 nm have been fabricated by calcination of electrospun zirconium acetylacetonate/polyacrylonitrile fibers in the range of 500–1100 °C. Composite and ceramic filaments have been characterized by scanning electron microscopy, thermogravimetric analysis, nitrogen adsorption analysis, energy-dispersive X-ray spectroscopy, and X-ray diffractometry. The stages of the transition of zirconium acetylacetonate to zirconia have been revealed. It has been found out that a rise in calcination temperature from 500 to 1100 °C induces transformation of mesoporous tetragonal zirconia nanofibers with a high specific surface area (102.3 m2/g) to non-porous monoclinic zirconia nanofibers of almost the same diameter with a low value of specific surface area (8.3 m2/g). The tetragonal zirconia nanofibers with high specific surface area prepared at 500 °C can be considered, for instance, as promising supports for heterogeneous catalysts, enhancing their activity.

Facile Controlled Synthesis of Manganese Oxide Hierarchical Microspheres by Hydrothermal Method

2011 ◽  
Vol 688 ◽  
pp. 107-115 ◽  
Author(s):  
Dong Yan Li ◽  
Yun Fa Chen
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Reaction ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Formation Mechanisms ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
Hydrothermal Temperature ◽  
Transmission Electron ◽  
Hierarchical Microspheres

MnO2hierarchical microsphere has been synthesized by a facile and direct hydrothermal reaction between KMnO4and HCl without the aids of catalysts, surfactants or templates. The as-prepared microsphere, as characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) analysis and nitrogen adsorption and desorption, is in form of K0.27MnO2(H2O )0.54, with a flower-like hierarchical microsphere structure and a BET surface area value of 52 m2/g. The morphology of the product can be simply tailed by controlled by reaction temperature or period and crystallinity can be modified by changing the concentrate of KMnO4. In general, excessive KMnO4and low hydrothermal temperature are favor to forming flower-like hierarchical structure. Besides, the formation mechanisms of the hierarchical schemes are proposed.

scholarly journals Synthesis and characterization of electrospun molybdenum dioxide–carbon nanofibers as sulfur matrix additives for rechargeable lithium–sulfur battery applications

2018 ◽  
Vol 9 ◽  
pp. 262-270 ◽  
Author(s):  
Ruiyuan Zhuang ◽  
Shanshan Yao ◽  
Maoxiang Jing ◽  
Xiangqian Shen ◽  
Jun Xiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Electrochemical Performance ◽  
Carbon Nanofibers ◽  
Lithium Ion ◽  
Cycle Performance ◽  
Bet Surface Area ◽  
Molybdenum Dioxide ◽  
Electrospinning Technique ◽  
Lithium Sulfur

One-dimensional molybdenum dioxide–carbon nanofibers (MoO2–CNFs) were prepared using an electrospinning technique followed by calcination, using sol–gel precursors and polyacrylonitrile (PAN) as a processing aid. The resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Brunauer–Emmet–Teller (BET) surface area measurements, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). MoO2–CNFs with an average diameter of 425–575 nm obtained after heat treatment were used as a matrix to prepare sulfur/MoO2–CNF cathodes for lithium–sulfur (Li–S) batteries. The polysulfide adsorption and electrochemical performance tests demonstrated that MoO2–CNFs did not only act as polysulfide reservoirs to alleviate the shuttle effect, but also improve the electrochemical reaction kinetics during the charge–discharge processes. The effect of MoO2–CNF heat treatment on the cycle performance of sulfur/MoO2–CNFs electrodes was examined, and the data showed that MoO2–CNFs calcined at 850 °C delivered optimal performance with an initial capacity of 1095 mAh g−1 and 860 mAh g−1 after 50 cycles. The results demonstrated that sulfur/MoO2–CNF composites display a remarkably high lithium–ion diffusion coefficient, low interfacial resistance and much better electrochemical performance than pristine sulfur cathodes.

Synthesis、Structure and Catalytic Activity of TiO2/ La2Zr2O7 Nanocomposites

2011 ◽  
Vol 239-242 ◽  
pp. 2878-2881
Author(s):  
Yu Ping Tong ◽  
Yu Qing Zhao ◽  
Hong Yuan Huo ◽  
Hui Yang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Sol Gel ◽  
Photocatalytic Property ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
X Ray ◽  
Scanning Electron

TiO2/La2Zr2O7 composites were fabricated by sol-gel method. The composites were characterized by X-ray powder diffraction (XRD), Raman spectrum, scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS) and Brunauer-Emmett-Teller (BET) nitrogen adsorption. The results showed that TiO2 was uniformly coated on the surface of La2Zr2O7 powders. The BET surface area of TiO2/La2Zr2O7 composites was 26.78 m2/g, which was larger than that of La2Zr2O7. Also, the photodegradation of methyl orange was used to evaluate its photocatalytic property. It was found that TiO2/La2Zr2O7 composites showed good photocatalytic activity and the decomposition of methyl orange had basically completed within 30 min.

scholarly journals The Role of the Aluminum Source on the Physicochemical Properties of γ-AlOOH Nanoparticles

2020 ◽  
Vol 39 (1) ◽  
pp. 89
Author(s):  
Rafael Romero Toledo ◽  
Luis M. Anaya Esparza ◽  
J. Merced Martínez Rosales
Keyword(s):  
Electron Microscopy ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Low Cost ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Precipitation Method ◽  
X Ray ◽  
Aluminum Salts ◽  
Adsorption Desorption

The effect on the physicochemical properties of aluminum salts on the synthesis of γ-AlOOH nanostructures has been investigated in detail using a hydrolysis-precipitation method. X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), were used to characterize the synthesized samples. The specific surface area, pore size distribution and pore diameter of the different γ-AlOOH structures were discussed by the N2 adsorption-desorption analysis. According to the results of the nanostructure, characterization revealed that for synthesized γ-AlOOH nanostructures from AlCl3 and Al(NO3)3, obvious XRD peaks corresponding to the bayerite phase are found indicating an impure γ-AlOOH phase. Furthermore, the nitrogen adsorption-desorption analysis indicated that the obtained γ-AlOOH nanoparticles from Al2(SO4)3 of technical grade (95.0 % of purity) and low cost, possess a high BET surface area of approximately 350 m2/g, compared to the obtained nanostructures from aluminum sources reactive grade, which was attributed to the presence of Mg (0.9 wt.%) in its nanostructure.

Carbon nanofibers grown on carbon fibers by chemical vapor deposition using the iron catalyst

2021 ◽  
Vol 95 ◽  
pp. 24-28
Author(s):  
Vuong Hoang Van ◽  
◽  
Duc Nguyen Van
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanofibers ◽  
Carbon Fibers ◽  
Vapour Deposition ◽  
Iron Catalyst ◽  
Chemical Vapour ◽  
Chemical Vapor ◽  
Processing Temperature ◽  
Gas Composition ◽  
Transmission Electron

Carbon nanofibers (CNFs) were synthesized by the catalytic chemical vapour deposition (CCVD) process using iron catalyst below the iron-carbon eutetic temperature (1147 oC). CNFs were formed on carbon fibers as substrates at the growth temperatures of 750, 800, and 850 oC. The effect of processing temperature on the formation and the morphology of CNFs was studied. Moreover, the effect of composition of gase mixture (C2H4, H2, and Ar) on the morphology of CNFs was also performed. The morphology and microstructure of as-obtained CNFs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED). Results revealed that temperature and gas composition play an important role in forming of CNFs.

Characterization of Pt-Doped WO3 Nanoparticles Synthesized by Flame Spray Pyrolysis

2012 ◽  
Vol 326-328 ◽  
pp. 394-399
Author(s):  
Thanittha Samerjai ◽  
Nittaya Tamaekong ◽  
Sukon Phanichphant
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Spray Pyrolysis ◽  
Nitrogen Adsorption ◽  
Single Step ◽  
Spherical Particles ◽  
Bet Surface Area ◽  
Flame Spray Pyrolysis ◽  
Flame Spray ◽  
Transmission Electron

Undoped WO3and WO3nanoparticles doped with 0.251.0 wt.% Pt were successfully produced in a single step by flame spray pyrolysis (FSP) [. Tungsten (VI) ethoxide 5% w/v in ethanol 99.8% and platinum (II) acetylacetonate were used as W and Pt precursors respectively dissolved in ethanol. The undoped WO3and Pt-doped WO3nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). The BET surface area (SSABET) of the nanoparticles was measured by nitrogen adsorption. From BET measurement,SSABETincreased anddBETdecreased with increasing Pt concentration from 0 to 1.0 wt.%. The morphology and accurate size of the primary particles were further investigated by high-resolution transmission electron microscopy (HRTEM). The crystallite size of undoped WO3spherical was found to be ranging from 520 nm and the crystallite sizes of 0.251.0 wt.% Pt-doped WO3spherical particles were found to be in the range of 520 nm.

scholarly journals A Feasible Way to Produce Carbon Nanofiber by Electrospinning from Sugarcane Bagasse

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1968 ◽  
Author(s):  
Wei Chen ◽  
Xin-Tong Meng ◽  
Hui-Hui Wang ◽  
Xue-Qin Zhang ◽  
Yi Wei ◽  
...  
Keyword(s):  
Carbon Nanofibers ◽  
Sugarcane Bagasse ◽  
Mass Fraction ◽  
Composite Nanofibers ◽  
Carbon Nanofiber ◽  
Average Diameter ◽  
Bet Surface Area ◽  
Natural Polymers ◽  
Nanofiber Mats ◽  
Thermal Stability Of

Recently, the nanofiber materials derived from natural polymers instead of petroleum-based polymers by electrospinning have aroused a great deal of interests. The lignocellulosic biomass could not be electrospun into nanofiber directly due to its poor solubility. Here, sugarcane bagasse (SCB) was subjected to the homogeneous esterification with different anhydrides, and the corresponding esterified products (SCB-A) were obtained. It was found that the bead-free and uniform nanofibers were obtained via electrospinning even when the mass fraction of acetylated SCB was 70%. According to the thermogravimetric analyses, the addition of SCB-A could improve the thermal stability of the electrospun composite nanofibers. More importantly, in contrast to the pure polyacrylonitrile (PAN) based carbon nanofiber, the SCB-A based carbon nanofibers had higher electrical conductivity and the surface N element content. In addition, the superfine carbon nanofiber mats with minimum average diameter of 117.0 ± 13.7 nm derived from SCB-A were obtained, which results in a larger Brunauer–Emmett–Teller (BET) surface area than pure PAN based carbon nanofiber. These results demonstrated that the combination of the homogeneous esterification and electrospinning could be a feasible and potential way to produce the bio-based carbon nanofibers directly from lignocellulosic without component separation.

scholarly journals Synthesis and Characterization of Rh/B–TNTs as a Recyclable Catalyst for Hydroformylation of Olefin Containing –CN Functional Group

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 755 ◽  
Author(s):  
Penghe Su ◽  
Xiaotong Liu ◽  
Ya Chen ◽  
Hongchi Liu ◽  
Baolin Zhu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Great Influence ◽  
Average Diameter ◽  
Atomic Emission ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Inner Diameter

The TiO2-based nanotubes (TNTs, B–TNTs) of different surface acidities and their supported Rh catalysts were designed and synthesized. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS), tempera–ture–programmed desorption of ammonia (NH3–TPD), atomic emission spectrometer (ICP), and Brunauer–Emmett–Tellerv (BET) surface-area analyzers. Images of SEM and TEM showed that the boron-decorated TiO2 nanotubes (B–TNTs) had a perfect multiwalled tubular structure; their length was up to hundreds of nanometers and inner diameter was about 7 nm. The results of NH3-TPD analyses showed that B–TNTs had a stronger acid site compared with TNTs. For Rh/TNTs and Rh/B–TNTs, Rh nanoparticles highly dispersed on B–TNTs were about 2.79 nm in average diameter and much smaller than those on TNTs, which were about 4.94 nm. The catalytic performances of catalysts for the hydroformylation of 2-methyl-3-butennitrile (2M3BN) were also evaluated, and results showed that the existence of B in Rh/B–TNTs had a great influence on the catalytic performance of the catalysts. The Rh/B–TNTs displayed higher catalytic activity, selectivity for aldehydes, and stability than the Rh/TNTs.

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