Research

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11 pages, 6515 KiB

Open AccessArticle

Fullerene-to-MWCNT Structural Evolution Synthesized by Arc Discharge Plasma

by Muhammad Sufi Roslan, Misbahul Muneer Abd Rahman, Muhamad Hanif Jofri, Kashif Tufail Chaudary, Azam Mohamad and Jalil Ali

C 2018, 4(4), 58; https://doi.org/10.3390/c4040058 - 25 Oct 2018

Cited by 4 | Viewed by 3745

Abstract

The growth of multi-walled carbon nanotubes (MWCNTs) has been extensively studied using electron microscopy. The ex situ structural behavior was examined to investigate the growth of the MWCNTs under different environments and pressures using electron microscopy. The arc discharge plasma technique was applied [...] Read more.

The growth of multi-walled carbon nanotubes (MWCNTs) has been extensively studied using electron microscopy. The ex situ structural behavior was examined to investigate the growth of the MWCNTs under different environments and pressures using electron microscopy. The arc discharge plasma technique was applied to synthesize the MWCNTs by evaporating carbon through the arc plasma between two cylindrical graphite rods, with a background pressure of 10⁻² to 10² mbar, inside a vacuum chamber under different ambient environments. The results showed that long MWCNT structures were successfully grown. We suggest that the mechanism involves: (i) fullerene formation; (ii) the elongation of fullerenes; and (iii) the growth of MWCNTs. Agglomeration with other structures then forms MWCNT bundles. We note that the pressure and environment in the vacuum chamber can affect the structure of the MWCNTs. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy and Carbon Materials)

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24 pages, 41966 KiB

Open AccessArticle

Trajectories of Graphitizable Anthracene Coke and Non-Graphitizable Sucrose Char during the Earliest Stages of Annealing by Rapid CO₂ Laser Heating

by Joseph P. Abrahamson, Abhishek Jain, Adri C. T. Van Duin and Randy L. Vander Wal

C 2018, 4(2), 36; https://doi.org/10.3390/c4020036 - 11 Jun 2018

Cited by 7 | Viewed by 4265

Abstract

The earliest stages of annealing of graphitizable anthracene coke and non-graphitizable sucrose char were observed by rapid heating with a CO₂ laser. Structural transformations were observed with transmission electron microscopy. Anthracene coke and sucrose char were laser heated to 1200 °C and [...] Read more.

The earliest stages of annealing of graphitizable anthracene coke and non-graphitizable sucrose char were observed by rapid heating with a CO₂ laser. Structural transformations were observed with transmission electron microscopy. Anthracene coke and sucrose char were laser heated to 1200 °C and 2600 °C for 0.25–300 s. The transformations are compared to traditional furnace heating at matching temperatures for a 1 h duration. Traditional furnace and CO₂ laser annealing followed the same pathway, based upon equivalent end structures. Graphitizable anthracene coke annealed faster than non-graphitizable sucrose char. Sucrose char passed through a structural state of completely closed shell nanoparticles that opened upon additional heat treatment and gave rise to the irregular pore structure found in the end product. The observed curvature in sucrose char annealed at 2600 °C results from shell opening. The initial presence of curvature and loss by heat treatment argues that odd membered rings are present initially and not formed upon heat treatment. Thus, odd membered rings are not manufactured during the annealing process due to impinging growth of stacks, but are likely present in the starting structure. The observed unraveling of the closed shell structure was simulated with ReaxFF. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy and Carbon Materials)

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8 pages, 10401 KiB

Open AccessArticle

Carbon Nanostructure Curvature Induced from the Rapid Release of Sulfur upon Laser Heating

by Joseph P. Abrahamson and Randy L. Vander Wal

C 2018, 4(2), 33; https://doi.org/10.3390/c4020033 - 22 May 2018

Cited by 3 | Viewed by 3215

Abstract

Laboratory-generated synthetic soot from benzene and benzene–thiophene was neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and furnace annealed. Furnace annealing of sulfur doped synthetic soot resulted in the formation of micro-cracks due to the high pressures caused by explosive sulfur evolution at elevated temperature. [...] Read more.

Laboratory-generated synthetic soot from benzene and benzene–thiophene was neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and furnace annealed. Furnace annealing of sulfur doped synthetic soot resulted in the formation of micro-cracks due to the high pressures caused by explosive sulfur evolution at elevated temperature. The heteroatom sulfur affected the carbon nanostructure in a different way than oxygen. Sulfur is thermally stable in carbon up to ~1000 °C and thus, played little role in the initial low temperature (500 °C) carbonization. As such, it imparted a relatively unobservable impact on the nanostructure, but rather, acted to cause micro-cracks upon rapid release in the form of H₂S and CS₂ during subsequent traditional furnace heat treatment. In contrast, Nd:YAG laser heating of the sulfur doped sample acted to induce curvature in the carbon nanostructure. The observed curvature was the result of carbon annealing occurring simultaneously with sulfur evolution due to the rapid heating rate. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy and Carbon Materials)

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15 pages, 4300 KiB

Open AccessArticle

Porous (Swiss-Cheese) Graphite

by Joseph P. Abrahamson, Ramakrishnan Rajagopalan and Randy L. Vander Wal

C 2018, 4(2), 27; https://doi.org/10.3390/c4020027 - 02 May 2018

Cited by 3 | Viewed by 4808

Abstract

Porous graphite was prepared without the use of template by rapidly heating the carbonization products from mixtures of anthracene, fluorene, and pyrene with a CO₂ laser. Rapid CO₂ laser heating at a rate of 1.8 × 10⁶ °C/s vaporizes out [...] Read more.

Porous graphite was prepared without the use of template by rapidly heating the carbonization products from mixtures of anthracene, fluorene, and pyrene with a CO₂ laser. Rapid CO₂ laser heating at a rate of 1.8 × 10⁶ °C/s vaporizes out the fluorene-pyrene derived pitch while annealing the anthracene coke. The resulting structure is that of graphite with 100 nm spherical pores. The graphitizablity of the porous material is the same as pure anthracene coke. Transmission electron microscopy revealed that the interfaces between graphitic layers and the pore walls are unimpeded. Traditional furnace annealing does not result in the porous structure as the heating rates are too slow to vaporize out the pitch, thereby illustrating the advantage of fast thermal processing. The resultant porous graphite was prelithiated and used as an anode in lithium ion capacitors. The porous graphite when lithiated had a specific capacity of 200 mAh/g at 100 mA/g. The assembled lithium ion capacitor demonstrated an energy density as high as 75 Wh/kg when cycled between 2.2 V and 4.2 V. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy and Carbon Materials)

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13 pages, 5844 KiB

Open AccessArticle

TEM Nano-Moiré Pattern Analysis of a Copper/Single Walled Carbon Nanotube Nanocomposite Synthesized by Laser Surface Implanting

by Jay F. Tu

C 2018, 4(1), 19; https://doi.org/10.3390/c4010019 - 20 Mar 2018

Cited by 13 | Viewed by 10484

Abstract

In our previous studies, we have developed a wet process to synthesize a copper-single walled carbon nanotube (Cu–SWCNT) metal nanocomposite with excellent mechanical properties. The nanostructure of this Cu–SWCNT composite was confirmed independently by energy-dispersive X-ray spectroscopy mapping, spectroscopy measurements, and Transmission Electron [...] Read more.

In our previous studies, we have developed a wet process to synthesize a copper-single walled carbon nanotube (Cu–SWCNT) metal nanocomposite with excellent mechanical properties. The nanostructure of this Cu–SWCNT composite was confirmed independently by energy-dispersive X-ray spectroscopy mapping, spectroscopy measurements, and Transmission Electron Microscope (TEM) images with discernable SWCNT clusters in nano sizes. However, TEM images with discernable nano-sized SWCNT clusters are rare. In this paper, we present analysis of indirect TEM image patterns, such as moiré fringes, to infer the existence of SWCNT clusters within the copper matrix. Moiré fringes or patterns in the TEM images of a Cu–SWCNT nanocomposite could be generated due to the overlapping of more than one thin crystals with similar periodic arrangements of atoms, promoted by SWCNT clusters. However, the presence of moiré patterns is not a sufficient or a necessary condition for the existence of SWCNT clusters. It was found that based on the overlapping angle of two periodic arrangements, it is feasible to distinguish the moiré fringes induced by SWCNT clusters from those by other factors, such as dislocations. The ability to identify SWCNTs within the copper matrix based on indirect TEM moiré patterns helps to widen the usability of TEM images. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy and Carbon Materials)

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Review

Jump to: Research

48 pages, 18208 KiB

Open AccessReview

Structure of Carbon Materials Explored by Local Transmission Electron Microscopy and Global Powder Diffraction Probes

by Karolina Jurkiewicz, Mirosława Pawlyta and Andrzej Burian

C 2018, 4(4), 68; https://doi.org/10.3390/c4040068 - 19 Dec 2018

Cited by 91 | Viewed by 19281

Abstract

Transmission electron microscopy and neutron or X-ray diffraction are powerful techniques available today for characterization of the structure of various carbon materials at nano and atomic levels. They provide complementary information but each one has advantages and limitations. Powder X-ray or neutron diffraction [...] Read more.

Transmission electron microscopy and neutron or X-ray diffraction are powerful techniques available today for characterization of the structure of various carbon materials at nano and atomic levels. They provide complementary information but each one has advantages and limitations. Powder X-ray or neutron diffraction measurements provide structural information representative for the whole volume of a material under probe but features of singular nano-objects cannot be identified. Transmission electron microscopy, in turn, is able to probe single nanoscale objects. In this review, it is demonstrated how transmission electron microscopy and powder X-ray and neutron diffraction methods complement each other by providing consistent structural models for different types of carbons such as carbon blacks, glass-like carbons, graphene, nanotubes, nanodiamonds, and nanoonions. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy and Carbon Materials)

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33 pages, 7240 KiB

Open AccessReview

A Library of Doped-Graphene Images via Transmission Electron Microscopy

by Phuong Viet Pham

C 2018, 4(2), 34; https://doi.org/10.3390/c4020034 - 28 May 2018

Cited by 16 | Viewed by 9305

Abstract

Much recent work has focused on improving the performance of graphene by various physical and chemical modification approaches. In particular, chemical doping of n-type and p-type dopants through substitutional and surface transfer strategies have been carried out with the aim of electronic and [...] Read more.

Much recent work has focused on improving the performance of graphene by various physical and chemical modification approaches. In particular, chemical doping of n-type and p-type dopants through substitutional and surface transfer strategies have been carried out with the aim of electronic and band-gap tuning. In this field, the visualization of (i) The intrinsic structure and morphology of graphene layers after doping by various chemical dopants, (ii) the formation of exotic and new chemical bonds at surface/interface between the graphene layers and the dopants is highly desirable. In this short review, recent advances in the study of doped-graphenes and of the n-type and p-type doping techniques through transmission electron microscopy (TEM) analysis and observation at the nanoscale will be addressed. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy and Carbon Materials)

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17 pages, 8633 KiB

Open AccessReview

Transmission Electron Microscopy of Carbon: A Brief History

by Peter J. F. Harris

C 2018, 4(1), 4; https://doi.org/10.3390/c4010004 - 12 Jan 2018

Cited by 35 | Viewed by 15022

Abstract

Transmission electron microscopy (TEM) has been used in the study of solid carbon since the 1940s. A number of important forms of carbon have been discovered through the use of TEM, and our understanding of the microstructure of carbon has largely been gained [...] Read more.

Transmission electron microscopy (TEM) has been used in the study of solid carbon since the 1940s. A number of important forms of carbon have been discovered through the use of TEM, and our understanding of the microstructure of carbon has largely been gained through the application of TEM and associated techniques. This article is an attempt to present an historical review of the application of TEM to carbon, from the earliest work to the present day. The review encompasses both graphitic carbon and diamond, and spectroscopic techniques are covered, as well as imaging. In the final section of the review, the impact of aberration-corrected TEM on current carbon research is highlighted. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy and Carbon Materials)

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