“…Under fluidization conditions, super-lightweight catalyst supports are randomly oriented in the whole fluidized bed during the CVD process; the gradients of temperature and carbon source concentration cause a discontinuous carbon growth. Therefore, the formation of a segmented structure is due to the unsaturation of carbon concentration on the deposition faces . TEM observations exhibit that the obtained nanofiber with an outer diameter of about 20 nm (Figure F) consists of well-ordered graphene platelets (Figure G) with a spacing of 0.342 nm, which is close to the ideal graphite lattice .…”
We report on the fabrication of 3D carbonaceous material composed of 1D carbon nanofibers (CNF) grown on 2D graphene sheets (GNS) via a CVD approach in a fluidized bed reactor. Nanographene-constructed carbon nanofibers contain many cavities, open tips, and graphene platelets with edges exposed, providing more extra space for Li(+) storage. More interestingly, nanochannels consisting of graphene platelets arrange almost perpendicularly to the fiber axis, which is favorable for lithium ion diffusion from different orientations. In addition, 3D interconnected architectures facilitate the collection and transport of electrons during the cycling process. As a result, the CNF/GNS hybrid material shows high reversible capacity (667 mAh/g), high-rate performance, and cycling stability, which is superior to those of pure graphene, natural graphite, and carbon nanotubes. The simple CVD approach offers a new pathway for large-scale production of novel hybrid carbon materials for energy storage.
“…Under fluidization conditions, super-lightweight catalyst supports are randomly oriented in the whole fluidized bed during the CVD process; the gradients of temperature and carbon source concentration cause a discontinuous carbon growth. Therefore, the formation of a segmented structure is due to the unsaturation of carbon concentration on the deposition faces . TEM observations exhibit that the obtained nanofiber with an outer diameter of about 20 nm (Figure F) consists of well-ordered graphene platelets (Figure G) with a spacing of 0.342 nm, which is close to the ideal graphite lattice .…”
We report on the fabrication of 3D carbonaceous material composed of 1D carbon nanofibers (CNF) grown on 2D graphene sheets (GNS) via a CVD approach in a fluidized bed reactor. Nanographene-constructed carbon nanofibers contain many cavities, open tips, and graphene platelets with edges exposed, providing more extra space for Li(+) storage. More interestingly, nanochannels consisting of graphene platelets arrange almost perpendicularly to the fiber axis, which is favorable for lithium ion diffusion from different orientations. In addition, 3D interconnected architectures facilitate the collection and transport of electrons during the cycling process. As a result, the CNF/GNS hybrid material shows high reversible capacity (667 mAh/g), high-rate performance, and cycling stability, which is superior to those of pure graphene, natural graphite, and carbon nanotubes. The simple CVD approach offers a new pathway for large-scale production of novel hybrid carbon materials for energy storage.
“…So far, the growth of diamond, carbon nanofibres and carbon nanotubes has been performed mostly through chemical vapour deposition (CVD), arc discharge and laser ablation methods [1][2][3][4][5][6]. Pulsed laser ablation (PLA) provides a means of depositing thin coatings, of a wide range of target materials, on a wide range of substrates, at room temperature.…”
Optical emission spectroscopy studies, in the spectral range ultraviolet-visible-near infrared (UV-Vis-NIR), were performed to investigate thermal and dynamical properties of a plume produced by laser ablation of a graphite target. Ablation is carried out using a high-power IR CO 2 pulsed laser at λ = 9.621 µm, power density ranging from 0.22 to 5.36 GW cm −2 and air pressures around 4 Pa. The strong emission observed in the plasma region is mainly due to electronic relaxation of excited C, ionic fragments C + , C 2+ and C 3+ and molecular features of C 2
“…The CNF batch #8 (Gupta's 19,20 formula) exhibits a segmented fiber architecture (Figure ) which should be favorable for gas storage applications. As shown in Figure b, the graphene layers are stacked indeed parallel to the base of the Ni/Cu particle following a growth mechanism as suggested by Chen et al 10 Segmented fiber architecture of batch #8 (see Table ) following the process route by Gupta et al: 19,20 (a) coarse-scale fiber microstructure (SE image) and (b) typical location of Ni/Cu catalyst within CNF (TEM bright field), see encircled area.…”
In 1996, R. T. K. Baker, and N. M. Rodriguez claimed to have synthesized a new type of carbon nanofiber material capable of storing large amounts of hydrogen at room temperature and pressures above 100 bar, thus making it a powerful candidate for a very efficient energy storage system in mobile applications. Consequently, many scientists all over the world tried to test and verify these findings, however, with partly inconsistent results. We present here for the first time independent hydrogen storage measurements for several types of nanofibers, both synthesized by our group following precisely the specifications given in the literature as well as original samples supplied by Rodriguez and Baker for this study. The hydrogen storage capacities at room temperature and pressures up to 140 bar were quantified independently by gravimetric and volumetric methods, respectively. No significant hydrogen storage capacity has been detected for all carbon nanofibers investigated.
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