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1.
Raman spectra of single crystalline two-dimensional rhombohedral (2D-R) polymer of C60 were measured at ambient conditions after its high temperature treatment (HTT) in order to study the polymer decomposition process. The data obtained indicate that the 2D-R polymer remains stable after 0.5 h treatment up to ∼503 K, while at higher temperatures a material transformation takes place. New Raman lines appear in the Raman spectrum after HTT in the range of 513-553 K, related to the Ag(2) pentagon pinch (PP) mode of 2D tetragonal-like (2D-T-like) and 1D orthorhombic-like (1D-O-like) oligomers as well as to C60 dimers and monomers, typical for an intermediate state of partially decomposed 2D-R polymer. Above 553 K, the material changes completely and its new composition is dominated by C60 monomers with some possible inclusion of C60 dimers. The activation energy of the 2D-R polymer decomposition, obtained from the dependence of the decomposition time on the treatment temperature, is EA = 1.76 ± 0.07 eV/molecule. 相似文献
2.
There is a pressing need to develop rapid whole animal-based testing assays to assess the potential toxicity of engineered nano-materials. To meet this challenge, the embryonic zebrafish model was employed to determine the toxicity of fullerenes. Embryonic zebrafish were exposed to graded concentrations of fullerenes [C60, C70, and C60(OH)24] during early embryogenesis and the resulting morphological and cellular responses were defined. Exposure to 200 μg/L C60 and C70 induced a significant increased in malformations, pericardial edema, and mortality; while the response to C60(OH)24 exposure was less pronounced at concentrations an order of magnitude higher. Exposure to C60 induced both necrotic and apoptotic cellular death throughout the embryo. While C60(OH)24 induced an increase in embryonic cellular death, it did not induce apoptosis. Our findings concur with results obtained in other models indicating that C60(OH)24 is significantly less toxic than C60. These studies also suggest that the embryonic zebrafish model is well-suited for the rapid assessment of nanomaterial toxicity. 相似文献
3.
Activation, characterization and hydrogen storage properties of the mesoporous carbon CMK-3 总被引:1,自引:0,他引:1
Activation of mesoporous carbon CMK-3 with CO2 for hydrogen storage was studied. Huge structure and texture changes emerged for the activated CMK-3 based on the characterization by using XRD, TEM and nitrogen adsorption at 77 K. The ordered mesoporous structure of CMK-3 gradually became disorder and its specific surface area and volume of pores especially micropores were enhanced remarkably. Hydrogen sorption measurement showed that the activation led to an obvious increase of the H2 sorption capacity of CMK-3. The maximum H2 uptake of 2.27 wt% at 77 K and 1 bar was obtained for the sample activated at 1223 K for 8 h. The small pores with the diameter smaller than 1 nm contributed greatly to the H2 uptake, and were confirmed more effective than other pores for hydrogen storage. 相似文献
4.
Hydrogen adsorption in different carbon nanostructures 总被引:1,自引:0,他引:1
Hydrogen adsorption in different carbonaceous materials with optimized structure was investigated at room temperature and 77 K. Activated carbon, amorphous carbon nanotubes, SWCNTs and porous carbon samples all show the same adsorption properties. The fast kinetics and complete reversibility of the process indicate that the interaction between hydrogen molecules and the carbon nanostructure is due to physisorption. At 77 K the adsorption isotherm of all samples can be explained with the Langmuir model, while at room temperature the storage capacity is a linear function of the pressure. The surface area and pore size of the carbon materials were characterized by N2 adsorption at 77 K and correlated to their hydrogen storage capacity. A linear relation between hydrogen uptake and specific surface area (SSA) is obtained for all samples independent of the nature of the carbon material. The best material with a SSA of 2560 m2/g shows a storage capacity of 4.5 wt% at 77 K. 相似文献
5.
Fullerene-Nafion composite membranes have been fabricated through a new solution casting for the first time. The fullerenes used for the composites included C60 and polyhydroxy fullerene (PHF), C60(OH)n (n ∼ 12). The dispersion of the fullerene in the composite membrane was much more refined with smaller agglomeration particles, relative to the previously prepared fullerene-Nafion composites in which the fullerene was introduced through doping. The miscibility of the hydrophobic fullerene, C60, in the Nafion matrix was further improved by a new fullerene dispersant, poly[tri(ethylene oxide)benzyl]fullerene, C60[CH2C6H4(OCH2CH2O)3OCH3]n (n ∼ 5), synthesized in this work. The solution-cast fullerene composites also demonstrated a significant improvement in the physical stability relative to the fullerene-doped Nafion composites through a better integration of the fullerene into the Nafion matrix. Furthermore, increased loadings of the fullerene in Nafion were made possible through the new solution-casting method, compared to the previous doping method. The water characteristics in the fullerene composites have been examined by TGA and 1H pulse NMR measurements. The interactions between the fullerene and the Nafion have been studied through ATR FT-IR and molecular dynamics simulations which suggested PHF resides primarily in the hydrophobic domain of Nafion when the loading was low. The voltammetric measurements also have shown that the fullerene composites have the reduced limiting current density, compared to Nafion membranes without fullerenes. 相似文献
6.
Graphene-like nanosheets have been synthesized by the reduction of a colloidal suspension of exfoliated graphite oxide. The morphology and structure of the graphene powder sample was studied using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The graphene sheets are found to be in a highly agglomerated state, with many wrinkles. The sample has a BET surface area of 640 m2/g as measured by nitrogen adsorption at 77 K. Hydrogen adsorption-desorption isotherms were measured in the temperature range 77-298 K and at pressures of up to 10 bar. This gives hydrogen adsorption capacities of about 1.2 wt.% and 0.1 wt.% at 77 K and 298 K, respectively. The isosteric heat of adsorption is in the range of 5.9-4 kJ/mol, indicating a favourable interaction between hydrogen and surface of the graphene sheets. The estimated room temperature H2 uptake capacity of 0.72 wt.% at 100 bar and the isosteric heat of adsorption of our sample are comparable to those of high surface area activated carbons, however significantly better than the recently reported values for graphene and a range of other carbon and nanoporous materials; single and multi walled carbon nanotubes, nanofibers, graphites and zeolites. 相似文献
7.
Hydrogen storage on chemically activated carbons and carbon nanomaterials at high pressures 总被引:1,自引:0,他引:1
Hydrogen adsorption measurements have been carried out at different temperatures (298 K and 77 K) and high pressure on a series of chemically activated carbons with a wide range of porosities and also on other types of carbon materials, such as activated carbon fibers, carbon nanotubes and carbon nanofibers. This paper provides a useful interpretation of hydrogen adsorption data according to the porosity of the materials and to the adsorption conditions, using the fundamentals of adsorption. At 298 K, the hydrogen adsorption capacity depends on both the micropore volume and the micropore size distribution. Values of hydrogen adsorption capacities at 298 K of 1.2 wt.% and 2.7 wt.% have been obtained at 20 MPa and 50 MPa, respectively, for a chemically activated carbon. At 77 K, hydrogen adsorption depends on the surface area and the total micropore volume of the activated carbon. Hydrogen adsorption capacity of 5.6 wt.% at 4 MPa and 77 K have been reached by a chemically activated carbon. The total hydrogen storage on the best activated carbon at 298 K is 16.7 g H2/l and 37.2 g H2/l at 20 MPa and 50 MPa, respectively (which correspond to 3.2 wt.% and 6.8 wt.%, excluding the tank weight) and 38.8 g H2/l at 77 K and 4 MPa (8 wt.% excluding the tank weight). 相似文献
8.
K.Yu. Amsharov 《Carbon》2007,45(1):117-123
In a retro-synthetic approach, [60]fullerene might be accessible by condensing six fulvalene fragments. In order to explore the potential of such a route for direct synthesis of [60]fullerene we have investigated the pyrolysis of perchlorofulvalene (PCF). Low temperature pyrolysis of PCF at 250 °C resulted mainly in the formation of dimers, trimers, tetramers and products of subsequent intramolecular condensation of these oligomers. Increasing the temperature to 300-350 °C leads to the formation of perchlorinated polynuclear aromatic hydrocarbons. Pyrolysis at 400-450 °C gives a cross-linked polymer structure which is the result of intermolecular condensation of the polynuclear aromatic intermediates. Pyrolysis at higher temperatures (>500 °C) mainly leads to graphite. It was found that the two-step pyrolysis of PCF (heating first at 450 °C, after that at 750 °C) yielded a fullerene containing soot via an intermediate polynuclear aromatic net. High temperature rearrangement of the latter gave fullerenes C60 and C70. The best results were obtained when a PCF oligomer obtained by Ullmann condensation was used as a precursor. By two-step pyrolysis and further high vacuum sublimation of the soot the fullerenes C60 and C70 were obtained in extractable amounts. 相似文献
9.
Using multi-walled carbon nanotubes (MWCNTs), the present study focuses on their electrochemical hydrogen storage capacities. The results showed that the hydrogen desorption process is composed of two steps with voltages around −0.75 and −0.15 V. Hydrogen adsorption at −0.15 V took place at temperatures above 30 °C, and the amount of energy required for adsorbing hydrogen was 1.68 eV. The hydrogen storage capacity increased with increasing electrolyte temperature from 30 to 60 °C in both steps. The hydrogen storage capacity of the MWCNTs treated at different atmospheres showed that the decrease in the graphitization of MWCNTs led to the increase in hydrogen adsorption. The results also showed that the MWCNTs treated in a CO2 atmosphere had the highest hydrogen storage capacity at −0.15 V. 相似文献
10.
A new synthetic medium for the production of C60 has been found that does not produce soot. C60 was produced in the liquid phase of an aerosol of precursor soot at 700 °C. The precursor soot aerosol, a high temperature stable form of hydrocarbon, was produced by pyrolysis of acetylene at atmospheric pressure in a flow tube reactor. At 700 °C, the effluent particles were found to contain PAHs, small hydrocarbons and fullerenes but no observable black material. However, when the reactor temperature was changed to 800 °C, soot was also produced in the effluent particles along with PAHs and other small hydrocarbons, and the fullerene product disappeared. These results show a clear competition between the production of fullerenes and other forms of carbon. The filter-collected effluent was shown to be completely soluble in conventional solvents suggesting the possibility of an efficient cyclic synthetic process. Fullerenes were only found in the particle phase implying the first observed liquid phase synthesis of C60. 相似文献
11.
Single-walled carbon nanotubes (SWCNTs) with diameter ranged from 1.22 to 1.6 nm filled with C60, C70 and C60H28 molecules (peapods), as well as double-walled carbon nanotubes (DWCNTs) derived from peapods, were studied by HRTEM, UV-vis-NIR and Raman spectroscopy. Suspensions with accurate concentration were used for spectroscopic studies to enable quantitative comparison of different substances. Filling of the SWCNTs with C70 molecules resulted in a reduced van der Waals interaction between the tubes in a bundle. The DWCNTs have lower intensity of the van Hove bands and weaker photoluminescence. Raman spectra at 633 and 1064 nm excitation wavelengths reveal that RBM frequencies of C60 and C70 peapods are equally downshifted compared to empty tubes. It was found that filling of the nanotubes with C60 and C70 caused spectral shifts of absorption bands: thin tubes display red shifts, while thick ones show blue shifts. DWCNTs and C60H28@SWCNTs do not show any shifts. All the results suggest that the filling of nanotubes with fullerenes alters the average diameter of the electron cloud around SWCNT framework; namely, it increases for thin SWCNTs, and decreases for thick ones. Our attempts to structurally assign thick nanotubes using reported extrapolations from data for thin tubes were unsuccessful. 相似文献
12.
A new synthetic medium for the production of C60 has been found that does not produce soot. C60 was produced in the liquid phase of an aerosol of precursor soot at 700 °C. The precursor soot aerosol, a high temperature stable form of hydrocarbon, was produced by pyrolysis of acetylene at atmospheric pressure in a flow tube reactor. At 700 °C, the effluent particles were found to contain PAHs, small hydrocarbons and fullerenes but no observable black material. However, when the reactor temperature was changed to 800 °C, soot was also produced in the effluent particles along with PAHs and other small hydrocarbons, and the fullerene product disappeared. These results show a clear competition between the production of fullerenes and other forms of carbon. The filter-collected effluent was shown to be completely soluble in conventional solvents suggesting the possibility of an efficient cyclic synthetic process. Fullerenes were only found in the particle phase implying the first observed liquid phase synthesis of C60. 相似文献
13.
Konstantin P. Katin Alexey I. Kochaev Savas Kaya Fadoua El-Hajjaji Mikhail M. Maslov 《International journal of molecular sciences》2022,23(4)
We theoretically investigated the adsorption of two common anti-COVID drugs, favipiravir and chloroquine, on fluorinated C60 fullerene, decorated with metal ions Cr3+, Fe2+, Fe3+, Ni2+. We focused on the effect of fluoridation on the interaction of fullerene with metal ions and drugs in an aqueous solution. We considered three model systems, C60, C60F2 and C60F48, and represented pristine, low-fluorinated and high-fluorinated fullerenes, respectively. Adsorption energies, deformation of fullerene and drug molecules, frontier molecular orbitals and vibrational spectra were investigated in detail. We found that different drugs and different ions interacted differently with fluorinated fullerenes. Cr3+ and Fe2+ ions lead to the defluorination of low-fluorinated fullerenes. Favipiravir also leads to their defluorination with the formation of HF molecules. Therefore, fluorinated fullerenes are not suitable for the delivery of favipiravir and similar drugs molecules. In contrast, we found that fluorine enhances the adsorption of Ni2+ and Fe3+ ions on fullerene and their activity to chloroquine. Ni2+-decorated fluorinated fullerenes were found to be stable and suitable carriers for the loading of chloroquine. Clear shifts of infrared, ultraviolet and visible spectra can provide control over the loading of chloroquine on Ni2+-doped fluorinated fullerenes. 相似文献
14.
Hydrogen storage by chemisorption on multiwalled carbon nanotubes (MWCNTs) was studied. Pristine MWCNTs could only store 0.1 wt.% of hydrogen at 573 K and ambient pressure, however, oxidation treatment to produce defects and subsequent loading with a Pd-Ni catalyst significantly increased the hydrogen storage capacity up to 6.6 wt.%. The hydrogen desorption temperature was above 500 K and an in situ diffuse reflectance IR Fourier-transform spectroscopy study indicated that the hydrogen was stored in the form of CHx (x = 1, 2) species. The study indicated that the most appropriate hydrogen chemisorption temperature was 550 K. For comparison, oxidized unloaded MWCNTs, oxidized MWCNTs separately loaded with either Pd or Ni, unoxidized fresh MWCNTs loaded with Pd-Ni, and activated carbon loaded with Pd-Ni were studied. The results showed that the defects and Pd-Ni catalyst were two essential factors for the high chemisorption of hydrogen on carbon nanotubes. 相似文献
15.
Hugues Duncan 《Electrochimica acta》2007,52(21):6195-6205
Hydrogen adsorption and absorption at thin palladium deposits of 0.8-10 monolayers (ML) on Au(1 1 1) was studied in 0.1 M H2SO4 and HClO4 using cyclic voltammetry, ac voltammetry, and impedance spectroscopy in the absence and in the presence of poison, crystal violet. Hydrogen adsorption on palladium is more reversible in sulfuric acid than in perchloric acid but it occurs at potentials 30 mV more positive in latter. The charge-transfer resistance exhibits a minimum at ∼0.27 V versus RHE and decreases with increasing in Pd deposit thickness in both acids. Adsorption capacitance at 0.8 ML Pd reaches maximum at the same potential. At other deposits the pseudo-capacitance starts to increase at lower overpotentials indicating the beginning of absorption, even at 2 ML Pd. The double layer capacitance is similar for all the deposits in sulfuric acid and it has a sharp maximum at 0.27 V versus RHE. In perchloric acid a broad maximum is observed. Crystal violet inhibits hydrogen adsorption but makes hydrogen absorption more reversible. The results suggest a fast direct hydrogen absorption mechanism that proceeds in parallel with slower hydrogen adsorption and indirect absorption. 相似文献
16.
J.L. PinillaR. Utrilla M.J. LázaroR. Moliner I. Suelves A.B. García 《Fuel Processing Technology》2011,92(8):1480-1488
Four catalysts, consisting of Ni, Ni:Cu, Fe or Fe:Mo as the active phase and Al2O3 or MgO as a textural promoter, were tested for the catalytic decomposition of methane in a rotary bed reactor, obtaining both CO2-free hydrogen and carbon nanostructures in a single step. Hydrogen yields of up to 14.4 Ndm3 H2·(h·gcat)− 1 were obtained using the Ni-based catalysts, and methane conversions above 80% were observed with the Fe-based catalysts. In addition to hydrogen production, the Ni-based catalysts allowed the large-scale production of fishbone-like carbon nanofibres, whereas the use of the Fe-based catalysts promoted the production of carbonaceous filaments having a high degree of structural order, consisting of both chain-like carbon nanofibres and carbon nanotubes. 相似文献
17.
Synthesis, electrochemical, and structural properties of LiNi0.8Co0.15Al0.05O2 cathodes prepared by TiO2 nanoparticles coating on a Ni0.8Co0.15Al0.05(OH)2 precursor have been investigated by the variation of coating concentration and annealing temperature. TiO2-coated cathodes showed that Ti elements were distributed throughout the particles. Among the coated cathodes, the 0.6 wt% TiO2-coated cathode prepared by annealing at 750 °C for 20 h exhibited the highest reversible capacity of 176 mAh g−1 and capacity retention of 92% after 40 cycles at a rate of 1C (=190 mA g−1). On the other hand, an uncoated cathode showed a reversible first discharge capacity of 186 mAh g−1 and the same capacity retention value to the TiO2-coated sample at a 1C rate. However, under a 1C rate cycling at 60 °C for 30 cycles, the uncoated sample showed a reversible capacity of 40 mAh g−1, while a TiO2-coated one showed 71 mAh g−1. This significant improvement of the coated sample was due to the formation of a possible solid solution between TiO2 and LiNi0.8Co0.15Al0.05O2. This effect was more evident upon annealing the charged sample while increasing the annealing temperature, and at 400 °C, the coated one showed a more suppressed formation of the NiO phase from the spinel LiNi2O4 phase than the uncoated sample. 相似文献
18.
Nano-crytalline hydrotalcite derived reduced mixed oxides containing magnesium, nickel and aluminium (MNAM) have been synthesized using coprecipitation and showed successfully nickel catalysed reversible hydrogen adsorption using the temperature programmed technique under near ambient conditions. ICP-MS and XRD analysis ensured the adsorbent homogeneity and different crystalline phases of mixed oxides. Morphology and textural properties of mixed oxides have been explored using the FESEM, BET and HRTEM analysis techniques. Nano-crystalline and mesporous reduced mixed oxides exhibited a 3.9 wt% H2 adsorption capacity in where desorption capacity was 1.9 wt% H2. Hydrogen adsorbed surface and different phases were analysed by XPS, Raman and FTIR analysis techniques. The hydrogen adsorption enthalpy (ΔH) and entropy (ΔS) changes of reduced mixed oxides were −47.58 kJ/mol and −120.98 J/mol K, respectively, and the promising desorption activation energy of 65 kJ/mol correspond its reversibility as potential energy storage material. 相似文献
19.
Adsorption of cadmium(II) from aqueous solution by surface oxidized carbon nanotubes 总被引:2,自引:0,他引:2
Carbon nanotubes (CNTs) were oxidized with H2O2, KMnO4 and HNO3. Their physicochemical properties were investigated by BET N2 adsorption, laser particle examination, Boehm’s titration, zeta potential measurement and cadmium(II) adsorption. The experimental results suggest that cadmium(II) adsorption capacities for three kinds of oxidized CNTs increase due to the functional groups introduced by oxidation compared with the as-grown CNTs. The cadmium(II) adsorption capacity of the as-grown CNTs is only 1.1 mg g−1, while it reaches 2.6, 5.1 and 11.0 mg g−1 for the H2O2, HNO3 and KMnO4 oxidized CNTs, respectively, at the cadmium(II) equilibrium concentration of 4 mg l−1. Adsorption of cadmium(II) by CNTs was strongly pH-dependent and the increase of adsorption capacities for HNO3 and KMnO4 oxidized CNTs is more obvious than that of the as-grown and H2O2 oxidized CNTs at lower pH regions. The experiments of CNT dosage effect on the cadmium(II) adsorption show that the adsorption capacity for KMnO4 oxidized CNTs has a sharper increase at the CNT dosage from 0.03 to 0.08 g per 100 ml than the as-grown, H2O2 and HNO3 oxidized CNTs and its removal efficiency almost reaches 100% at CNT dosage of 0.08 g per 100 ml. Analysis revealed that the KMnO4 oxidized CNTs hosted manganese residuals, and these surely contributed to cadmium sorption to a yet-undefined extent. 相似文献
20.
An energetic analysis was performed to study the interactions of C60 molecules encapsulated in carbon nanotubes. Both direct interaction between C60 molecules through van der Waals forces and indirect interaction between encapsulated C60 molecules through the elastic deformation of their host carbon nanotubes were considered. For C60s encapsulated in a (9, 9) nanotube, the indirect interaction dominates and a relatively large energy barrier exists for the formation of a uniform, stable, one-dimensional (1-D) C60 array. For a (10, 10) nanotube, the indirect interaction leads to a small energy barrier to form a 1-D C60 array, while for a (11, 11) nanotube the influence of the indirect interaction is negligible. Molecular dynamics simulations were performed to confirm the present energetic analysis, suggesting that the indirect interaction between encapsulated molecules/particles through the elastic deformation of their host nanotubes may affect the stability of nanotube-based structures. 相似文献