Influence of chemical bond of carbon on Ni catalyzed graphitization

Yudasaka, Masako; Tasaka, Kohji; Kikuchi, Rie; Ohki, Y.; Yoshimura, Susumu; Ota, Etsuro

doi:10.1063/1.365339

Cited by 47 publications

(28 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ni-catalyzed graphitization of carbon materials with different degrees of crystalline order have been investigated, with the highest catalytic activity found in glass-like carbon and the lowest found in natural graphite [12] . Yudasaka et al [9] found that Ni-catalyzed graphitization was dependent on the carbon bond, with the sp3 carbons more easily graphitized by Ni than the sp2 carbons; catalytic graphitization mechanisms have been considered in detail [4,5,9,11] . However there appears to be a dearth of literature on the Ni-catalyzed graphitization of PAN-based carbon fi bers.…”

Section: Introductionmentioning

confidence: 99%

“…Many efforts have focused on achieving graphitization at relatively low temperatures through the addition of either organic or inorganic catalysts [4][5][6][7][8][9][10][11][12][13] . Nickel has been found to be one of the most effective catalysts for the graphitization of amorphous carbons [8][9][10][11][12][13] , with catalytic Ni graphitization of amorphous carbon fi lms at about 700 K reported [11] . Ni-catalyzed graphitization of carbon materials with different degrees of crystalline order have been investigated, with the highest catalytic activity found in glass-like carbon and the lowest found in natural graphite [12] .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of anodization on the graphitization of PAN-based carbon fibers of PAN-based carbon fibers

Yao

et al. 2011

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

View full text Add to dashboard Cite

One-step pretreatment, anodization, is used to activate the polyacrylonitrile (PAN)-based carbon fi bers instead of the routine two-step pretreatment, sensitization with SnCl 2 and activation with PdCl 2 . The effect of the anodization pretreatment on the graphitization of PAN-based carbon fi bers is investigated as a function of Ni-P catalyst. The PAN-based carbon fi bers are anodized in H 3 PO 4 electrolyte resulting in the formation of active sites, which thereby facilitates the following electroless Ni-P coating. Carbon fi bers in the presence and absence of Ni-P coatings are heat treated and the structural changes are characterized by X-ray diffraction and Raman spectroscopy, both of which indicate that the graphitization of PAN-based carbon fi bers are accelerated by both the anodization treatment and the catalysts Ni-P. Using the anodized carbon fi bers, the routine two-step pretreatment, sensitization and activation, is not needed.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of anodization on the graphitization of PAN-based carbon fibers of PAN-based carbon fibers

Yao

et al. 2011

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

View full text Add to dashboard Cite

show abstract

“…3 We note the temperatures of graphitization by adding Ni to diamond, and DLC lie between 500 and 900°C. 2 In contrast, all our samples were grown at 300 K to avoid the formation of graphitic or crystalline phase change.…”

Section: -mentioning

confidence: 99%

“…1 In spite of the unique ability of carbon to mix with a large number of heavy elements, synthesis of a homogeneous amorphous phase of metalcarbon remains difficult. [2][3][4][5] Nickel has been used for the recrystallization of carbon or the graphitization of carbon at high temperature ͑ϳ500°C͒. 2,3 In the microstructure of metal and carbon multilayers fabricated by ion bombardment or sputtering, the formation of metal and carbon clusters was attributed to non-homogeneous structures in the films.…”

mentioning

confidence: 99%

“…2-5 Nickel has been used for the recrystallization of carbon or the graphitization of carbon at high temperature ͑ϳ500°C͒. 2,3 In the microstructure of metal and carbon multilayers fabricated by ion bombardment or sputtering, the formation of metal and carbon clusters was attributed to non-homogeneous structures in the films. 4 Similarly, when mixed phase materials were attempted by substitutional doping of diamond by metal atoms or preparation of diamond-metal composites, they yielded only metallic films having no signature of activated conduction.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Semiconducting phase of amorphous carbon-nickel composite films

Bhattacharyya

Henley

Lock

et al. 2006

Applied Physics Letters

View full text Add to dashboard Cite

Amorphous carbon-nickel composite films, which constitute a homogeneously mixed phase of carbon and 10% nickel, are prepared by UV pulsed laser ablation. From the low temperature conductivity study of these films, a nearly activated conduction followed by conductivity saturation below a temperature of 25 K has been identified. This is very different from undoped diamond-like carbon ͑DLC͒ films. The presence of additional density of states at the Fermi level observed in these samples when compared with DLC films, is directly confirmed using valence band spectroscopy. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2216030͔In the past, many attempts have been made to increase electrical conduction in diamond and amorphous diamondlike carbon ͑DLC͒ films by incorporating various light and heavy elements in order to "dope" them and make controllable semiconducting materials. One of the difficulties for substitutional doping of carbon is the formation of unstable graphitic structures, which results in a high defect density of states ͑DOS͒ at the Fermi level ͑E F ͒. Although several examples of conductivity enhancement of amorphous carbon ͑a-C͒ films alloyed with light elements such as nitrogen were found, a true signature of activated or delocalized transport has rarely been demonstrated. 1 In spite of the unique ability of carbon to mix with a large number of heavy elements, synthesis of a homogeneous amorphous phase of metalcarbon remains difficult. 2-5 Nickel has been used for the recrystallization of carbon or the graphitization of carbon at high temperature ͑ϳ500°C͒. 2,3 In the microstructure of metal and carbon multilayers fabricated by ion bombardment or sputtering, the formation of metal and carbon clusters was attributed to non-homogeneous structures in the films. 4 Similarly, when mixed phase materials were attempted by substitutional doping of diamond by metal atoms or preparation of diamond-metal composites, they yielded only metallic films having no signature of activated conduction. 5 Due to the formation of metal clusters and nanostructures, tunneling of electrons was found to dominate the conduction processes even at high temperatures and therefore, an activated conduction, showing a small energy gap at low temperature, was rarely observed. 5 We show that to achieve a homogeneous amorphous phase or embedded nanostructures, laser ablation can be utilized to mix insulators and metals. Metal catalysts mixed with carbon are routinely used for the growth of various nanostructures such as carbon nanotubes, at high temperature, where supersaturation of the vapor phase of carbon and metal is crucial in the formation of a stable metal-free carbon nanostructure. 6 It seems that by controlling the temperature and energy, the degree of supersaturation of the carbon-metal mixture can be achieved, giving rise to a metastable amorphous phase. Keeping in mind that the initial state of carbon is important to transform the film structure, we introduce Ni into highly insulating sp 3 carbon films by laser ablation t...

show abstract

Vertically Aligned Graphene Layer Arrays from Chromonic Liquid Crystal Precursors

et al. 2010

View full text Add to dashboard Cite

Progress in graphene synthesis has led to increased interest in the assembly of graphene into superstructures, and to the fabrication of novel ordered materials from graphene or engineered graphenic molecular building blocks. [1][2][3][4][5][6][7][8] Graphene monolayers typically deposit fl at on substrates or associate face-to-face to form horizontal stacked papers or multilayer coatings. [8][9][10][11] The opposite structure, vertically aligned graphene layer arrays on substrates ( Figure 1 A ), are more diffi cult to fabricate, but are expected to show a range of unique properties and behaviors. Their high concentration of edge-sites at the top surface would allow functionalization at high density for superhydrophobic/ philic coatings, high-redox-activity electrode surfaces, or chemically patterned surfaces for cell adhesion and guidance. The vertical layer orientation would allow rapid intercalation and deintercalation of lithium in high-discharge-rate thin fi lm batteries, [ 12 ] and would provide high Z -directional thermal/electrical conductivity. If also ordered in a second dimension, such arrays would be anisotropic in the substrate plane and provide unidirectional in-plane heat spreading or optical polarization. If the heights of arrays can be limited to below 50 nm, they may fi nd application as transparent conductive fi lms, [ 10 , 13 ] or as graphene nanoribbons where the ribbon width is set by the array height. Here we use chromonic liquid crystal precursors to fabricate vertically aligned graphene layer arrays (VAGLAs) on substrates and also demonstrate a method to achieve full two-dimensional order, which we defi ne as further control of graphene layer orientational patterns within the substrate plane using local shear-forces. We also demonstrate one example of a unique property of these arrays -the ability to etch Zdirectional nanopores by catalytic hydrogenation, in which cobalt nanoparticles tunnel vertically into and through the arrays as they track vertically receding edge-plane surfaces.A promising route to the desired vertical graphene array structure is one based on polyaromatic precursors, [ 2 ] which can adopt edge-on orientation on substrates. [ 5 , 14 , 15 ] Many polyaromatic compounds, however, do not retain supramolecular alignment upon carbonization, and also their solution or vapor deposition typically gives only short-range order in-plane. [ 2 ] Liquid crystal phases offer long-range order, but most discotic phases are high-temperature viscous liquids that are diffi cult to process and their supramolecular order can also be unstable during carbonization. [ 1 ] A promising solution to these challenges are so-called "chromonic liquid crystals" (CLCs), which combine graphenic disk assembly with water solubility. CLCs are formed from water soluble organic dyes which form massive π -stacks in aqueous solution that act as supramolecular rods. These structures then order into nematic liquid crystal phases through rod self-avoidance at high concentration [ 1 , 16-18 ]

show abstract

Influence of chemical bond of carbon on Ni catalyzed graphitization

Cited by 47 publications

References 10 publications

Effect of anodization on the graphitization of PAN-based carbon fibers of PAN-based carbon fibers

Effect of anodization on the graphitization of PAN-based carbon fibers of PAN-based carbon fibers

Semiconducting phase of amorphous carbon-nickel composite films

Vertically Aligned Graphene Layer Arrays from Chromonic Liquid Crystal Precursors

Contact Info

Product

Resources

About