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1.
The properties and applications of CNT have been studied extensively since Iijima discovered them in 1991[1,2]. They have exceptional mechanical properties and unique electrical property, highly chemical stability and large specific surface area. Thus far, they have widely potential applications in many fields. They can be used as reinforcing materials in composites[3], field emissions[4], hydrogen storage[5], nanoelectronic components[6], catalyst supports[7], adsorption material and so on.… 相似文献
2.
Kekule structures of different carbon species have been determined. On the basis of Kekule structure and C-C bond counts as well as the surface curvature, stability of diverse carbon species, driving force for curling of graphite fragments and formation of fullerenes and nanotubes, have been discussed. Curling of graphite flat fragments, end-capping of nanotubes, and closure of curved structures are driven by a tremendous increase in Kekule structures as terminal carbon atoms couple their dangling bonds into C-C o bonds. The increasing tendency becomes particularly striking for large cages and nanotubes. Resonance among numerous Kekule structures will stabilize the curved structure and dominate formation of closed carbon species. For similar carbon cages with comparable Kekule structure counts in magnitude, the surface curvature of carbon cages, as a measure for the strain energy, also plays an important role in determining their most stable forms. 相似文献
3.
ZHANG Xingtang WANG Yumei ZHANG Chunmei JIANG Xiaohong TIAN Baoli LI Yuncai HUANG Yabin & DU Zuliang Key Laboratory for Special Functional Materials Henan University Kaifeng China Correspondence should be addressed to Du Zuliang 《中国科学B辑(英文版)》2006,49(2):155-161
1 Introduction In 1998, Kasuga et al. obtained a new kind of nanotubular materials by treating anatase TiO2 power with concentrated NaOH aqueous solution[1,2]. This work soon aroused general concern due to their exten- sive applications in the photoelectr… 相似文献
4.
Understanding the self-assembly behavior of β-sheet peptides is important, not only in constructing bioactive peptide nanostructures, but also in inhibiting uncontrollable protein aggregation in protein-misfolding diseases. Here, the first systematic investigation of combination self-assembly between β-sheet block copolypeptides and CNTs is presented, demonstrating the presence of several different association modes during the combination self-assembly process. Bioactive β-sheet block copolypeptides can self-assemble by themselves, or can be used to functionalize CNT hybrids depending on the situation. This behavior may be important both for fabricating bioactive peptide/CNT hybrids and for controlling/inhibiting protein-misfolding diseases. 相似文献
5.
<正>Molecular nanotubes are nanoscale organic materials with tubular architecture, that show potential applications in molecular recognition/separation, cross-membrane transportation, catalysis in confined spaces, and nanoelectronics [1]. However, the precise construction of molecular nanotubes with well-defined cavity sizes and shapes is non-trivial. 相似文献
6.
Multi-walled carbon nanotubes–thermoplastic polyurethanes composites were characterized by means of differential scanning calorimetry and dielectric relaxation spectroscopy. The composite is characterized by two glass transition temperatures T g . The T g associated with the soft segment decreases by increasing of carbon nanotubes content, while carbon nanotubes content has practically no effect on the value of the T g associated with the hard segments. It was observed that rising the temperature and carbon nanotubes content resulted in the increased of both the dielectric permittivity and the loss factor. The presence of carbon nanotubes produces an enhancement of charge carriers trapping, increasing the electrical conductivity. The electrical conductivity of the composite was found to exhibit an insulator to conductor transition at a carbon nanotubes critical content, i.e., the percolation threshold, near 6 wt %. 相似文献
7.
A simple one-step route for preparing α-MnO(2) nanotubes is reported. The α-MnO(2) nanotubes exhibit a high surface area of 226 m(2) g(-1) and reversible capacity of 512 mA h g(-1) at a high current density of 800 mA g(-1) after 300 cycles, as well as cycling stability when measured as an anode in lithium batteries. 相似文献
8.
Nan Zhang Qin Zhang Ke Wang Hua Deng Qiang Fu 《Journal of Thermal Analysis and Calorimetry》2012,107(2):733-743
The effects of nucleating duality, imposed by a mixed nucleating agent (NA) system containing multi-walled carbon nanotubes
(MWCNTs) and a rare earth (WBG), on the crystallization behaviors of isotactic polypropylene (iPP) including the peak temperature
of crystallization (T
cp), polymorphic composition, and crystalline morphology, were probed in detail by calorimetry, X-ray diffraction, and polarized
light microscopy. In such mixed nucleating agent system, MWCNTs is active filler to induce α-nucleation for iPP, while WBG
serves as β-nucleating agent. When the WBG content was low (0.05%), the crystals of WBG were as a form of individual isotropic
dendrite, and the enhancement of T
cp was achieved by the incorporation of MWCNTs. As the WBG content was high as 0.1%, a percolated NA network consisted of needlelike
crystals of WBG yielded before nucleating the prevalent crystallization of iPP. In this case, the addition of MWCNTs has no
obvious effect on T
cp. However, by varying the mass proportion of MWCNTs/WBG, the polymorphic composition was adjusted significantly, indicating
a nucleation competition between MWCNTs and WBG. Although the competitive growth existed between α-crystals nucleated by MWCNTs
and β-crystals nucleated by WBG, the formation of primary β-crystallite was always prior to the α-nucleated crystallization,
as confirmed by crystalline morphology. These findings are useful for developing a new pathway to prepare iPP-based composite
with good mechanical property via the addition of mixed nucleating system containing active inorganic filler and β-nucleating
agent. 相似文献
9.
Limin Guo Jianling Zhao Xixin Wang Rongqing Xu Yangxian Li 《Journal of Solid State Electrochemistry》2009,13(9):1321-1326
The formation and growth of a self-organized zirconia porous layer can be achieved directly by anodization of Zr in chloride
containing electrolytes. The morphology of the porous layers is affected by electrochemical conditions such as Cl− concentration. Zirconia nanotubes with diameters ranging from 250 to 300 nm and a length of 33 μm were formed under proper
conditions. The nanotubes have smooth and straight walls. The composition of the nanotubes was characterized by using an energy
dispersive spectrometer. Selected area electron diffraction investigation reveals that the as-anodized zirconia nanotubes
have an amorphous structure. Crystal phase transition and structural stability of the ZrO2 nanotubes after heat treatment were characterized. A possible growth mechanism is presented. 相似文献
10.
Since secondary structure elements are known to play a key role in stabilizing the 3D-fold of proteins for the design of non-natural proteins composed of beta-amino acid residues, the construction of suitable secondary structural elements is mandatory. Folding analogues of alpha-helices and beta-strands of beta-polypeptides were already described (Chem. Biodiversity 2004, 1, 1111 (1)). Here, we present several collagen-like folds composed exclusively of beta-Ala(s). Unlike their natural counterpart, these tubular nanostructures can be composed of more than three polypeptide chains aligned parallel and/or antiparallel. By using ab initio and DFT calculations we have optimized a large number of versatile collagen-like antiparallel nanostructures. In these tubular systems, oligopeptide strands are interconnected by i --> (i) type H-bonds, except for the "closing" set. This latter is called "the H-bond zipper" and is either (i) --> i, ( i + 1) --> i, or ( i + 2) --> i type. Antiparallel, tubular foldamers composed of l number of strands, each of k number of beta-amino acid residues (e.g., apbeta-T(l) i+l ) k , ap(beta-T(l) i+1 ) k , or ap(beta-T(l) i+2 ) k ), are unexpectedly stable supramolecular complexes. Independent of k and l, the local backbone fold of the amino acid residues is usually spiral, abbreviated as "S(P)" or "S*(P)". Nevertheless, in contrast to parallel, in antiparallel nanotubes the backbone fold can occasionally twist out from S(P) or S*(P) type into an alternative local structure. However, the more the local geometry of the strands resembles to S(P) or S*(P), the higher the stability is. Besides the backbone twisting, the overall stability is determined by the type and the geometrical properties of the constituent H-bonds. Interestingly, higher number of total H-bonds can provide a lower overall stability, when H-bond parameters are inferior. In general, the increase of both the number of strands and their length stabilize the supramolecular complex. Now that, for beta-peptides, collagen-like overall folds with their stability were determined, their POG- or PPG-like sequence specificity has to be revealed. 相似文献
11.
A. A. Dyshin O. V. Eliseeva G. V. Bondarenko A. M. Kolker M. G. Kiselev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(12):2434-2439
A way of dispersing single-walled carbon nanotubes in preparing stable suspensions with high concentrations of individual nanotubes in amide solvents is described. The obtained suspensions are studied via Raman spectroscopy. The dependence of the degree of single-walled carbon nanotube (SWNT) dispersion in individual and mixed amide solvents on the type of solvent, the mass of nanotubes, and the concentration of cholic acid is established. A technique for processing spectral data to estimate the diameters and chiralities of individual nanotubes in suspension is described in detail. 相似文献
12.
Xuewan Wang Xiuan Xi Ge Huo Chenyu Xu Pengfei Sui Renfei Feng Xian-Zhu Fu Jing-Li Luo 《Journal of Energy Chemistry》2021,(2):49-55,I0002
Biomolecules with a broad range of structure and heteroatom-containing groups offer a great opportunity for rational design of promising electrocatalysts via versatile chemistry.In this study,uniform folic acid-Co nanotubes(FA-Co NTs) were hydrothermally prepared as sacrificial templates for highly porous Co and N co-doped carbon nanotubes(Co-N/CNTs) with well-controlled size and morphology.The formation mechanism of FA-Co NTs was investigated and FA-Co-hydrazine coordination interaction together with the H-bond interaction between FA molecules was characterized to be the driving force for growth of one-dimensional nanotubes.Such distinct metal-ligand interaction afforded the resultant CNTs rich Co-N_x sites,hierarchically porous structure and Co nanoparticle-embedded conductive network,thus an overall good electrocatalytic activity for oxygen reduction.Electrochemical tests showed that Co-N/CNTs-900 promoted an efficient 4 e ORR process with an onset potential of 0.908 V vs.RHE,a limiting current density of 5.66 mA cm-2 at 0.6 V and a H_2 O_2 yield lower than 5%,comparable to that of 20%Pt/C catalyst.Moreover,the catalyst revealed very high stability upon continuous operation and remarkable tolerance to methanol. 相似文献
13.
14.
E. F. Kustov 《Doklady Physical Chemistry》2016,469(2):111-116
Nanotubes (NTs) are mainly represented by (n,p) chiral NTs with chirality indices 0 < p < n delimited by (n,0) and (n,n) for achiral NTs. In (n,p) chiral NTs, the unit cell hexagons have a helical arrangement on the cylindrical surface of an NT and common angular and axial translations. An analytical formula was derived for calculation of the band structure of both chiral and achiral NTs with chirality indices 0 ≤ p ≤ n and band diagrams of some chiral NTs. Chiral NTs significantly extend the range of semiconducting NTs. An equation for the band gap width ΔЕ of semiconducting chiral and achiral NTs was derived: \(\frac{{\vartriangle E}}{{{\gamma _0}}} = \frac{{2\pi }}{{\sqrt {3{n^2} + 3np + 3{p^2}} }}\). Tables of the band structure parameters of metallic and semiconducting chiral NTs are presented. 相似文献
15.
We investigated by Ar and Kr adsorption isotherm techniques for two kinds of carbon single-wall nanotube bundles prepared
by different synthesis methods. Despite the difference in the adsorption capacity in the two samples, the adsorption mechanisms
are similar, which indicates that the same adsorption sites are involved for Ar and Kr. We have already measured a similar
difference in the adsorbed amount in these samples studied by a low-temperature heat-capacity technique, i.e., for the case
of 4He as adsorbate. These results cannot be easily explained by only taking into account the topology of the bundles if all tubes
are closed-ended. A larger spread of effective surface areas among different sources of samples is reported in the literature
data. 相似文献
16.
《Electrochemistry communications》2008,10(11):1669-1672
TiO2@Sn core–shell nanotube material prepared by thermal decomposition of SnCl4 on TiO2 nanotubes at 300 °C has been demonstrated superior Li-ion storage capability of 176 mA h/g even at high current rate of 4000 mA/g (charge and discharge of all TiO2 within 5 min) in spite of using low carbon content (5 wt%). This value corresponds to volumetric energy densities of 317 mA h/cm3, and its value was 3.5-fold larger than that of the bare TiO2 nanotubes. 相似文献
17.
《Electrochemistry communications》2008,10(1):123-126
This work reports on a novel chitosan–hematite nanotubes composite film on a gold foil by a simple one-step electrodeposition method. The hybrid chitosan–hematite nanotubes (Chi–HeNTs) film exhibits strong electrocatalytic reduction activity for H2O2. Interestingly, two electrocatalytic reduction peaks are observed at −0.24 and −0.56 V (vs SCE), respectively, one controlled by surface wave and the other controlled by diffusion process. The Chi–HeNTs/Au electrode shows a linear response to H2O2 concentration ranging from 1 × 10−6 to 1.6 × 10−5 mol L−1 with a detection limit of 5 × 10−8 mol L−1 and a sensitivity as high as 1859 μA μM−1 cm−2. 相似文献
18.
Chun Hai Yang Cheng Guo Hu Sheng Shui Hu 《中国化学快报》2007,18(3):313-315
Stable adsorption and direct electrochemistry of glucose oxidase (GOx) occurred on nitric acid (HNO3)-treated multi-walled carbon nanotubes (MWNTs) instead of as-received MWNTs, demonstrating the critical roles of oxygen-containing groups in stableadsorption and direct electrochemistry of GOx on carbon nanotubes (CNTs). 相似文献
19.
Sarawut Tontapha Nongnit Morakot Vithaya Ruangpornvisuti Banchob Wanno 《Structural chemistry》2012,23(6):1819-1830
The binding abilities of transition metals (TMs) (TMs?=?Ni, Pd, and Pt) on perfect and Stone?CWales (SW) defective armchair (5,5) single-walled boron nitride nanotubes (BNNTs) were investigated using density functional theory method at the B3LYP/LanL2DZ level. The geometrical parameters and electronic properties of all BNNTs doped with TM atoms are reported. The strongest binding energy of Ni doped on SW defective BNNT of ?91.87?kcal/mol was found. The binding abilities of the most stable of TMs on the BNNTs are in order: Ni/SW2?CBNNT(ZN)?>?Pt/SW2?CBNNT(ZB)?>?Pd/SW2?CBNNT(ZB). In all case, energy gaps of MTs doped perfect and defective BNNTs are obviously lower than their undoped nanotubes. 相似文献
20.
Xinya Jiang Yaqin Chai Ruo Yuan Yaling CaoYingfeng Chen Haijun WangXianxue Gan 《Analytica chimica acta》2013
In the present study, a novel and ultrasensitive electrochemiluminescence (ECL) immunosensor based on luminol cathodic ECL was fabricated by using Au nanoparticles and Pt nanoparticles (nano-AuPt) electrodeposited on graphene–carbon nanotubes nanocomposite as platform for the detection of carcinoembryonic antigen (CEA). For this introduced immunosensor, graphene (GR) and single wall carbon nanotubes (CNTs) dispersed in chitosan (Chi-GR-CNTs) were firstly decorated on the bare gold electrode (GE) surface. Then nano-AuPt were electrodeposited (DpAu-Pt) on the Chi-GR-CNTs modified electrode. Subsequently, glucose oxidase (GOD) was employed to block the non-specific sites of electrode surface. When glucose was present in the working buffer solution, GOD immediately catalyzed the oxidation of glucose to in situ generate hydrogen peroxide (H2O2), which could subsequently promote the oxidation of luminol with an amplified cathodic ECL signal. The proposed immunosensor was performed at low potential (−0.1 to 0.4 V) and low concentration of luminol. The CEA was determined in the range of 0.1 pg mL−1 to 40 ng mL−1 with a limit of detection down to 0.03 pg mL−1 (S N−1 = 3). Moreover, with excellent sensitivity, selectivity, stability and simplicity, the as-proposed luminol-based ECL immunosensor provided great potential in clinical applications. 相似文献