A theoretical study of the dihydrogen molecule confined inside carbon nanotubes

The aim of this work is to better understand the interaction between the confined dihydrogen molecule and armchair (2,2), (3,3) (4,4), (5,5), and (6,6) single‐walled carbon nanotubes (SWNT) using Restricted Hartree–Fock (RHF) and Density Functional Theory (DFT) methods using B3LYP and CAM‐B3LYP functionals. Depending on the calculation method and its orientation inside the nanotube, H₂ binds differently. We found that H? H bond length increases when H₂ is trapped in CNT (2,2) and decreases for CNT (3,3) and (4,4). The characteristics of confined H₂ in (5,5) and (6,6) nanotubes are similar to H₂ in a free state. © 2013 Wiley Periodicals, Inc.     

氢气辅助的水中埋弧法制备小直径碳纳米管

用改进的石墨电弧放电方法制备了小直径、高质量的碳纳米管,以水为打弧介质,氢气为保护气体.该方法具有装置简单,电流小,无催化剂,制备出的多壁碳纳米管直径小于10 nm等优点.     

Influence of high vacuum annealing treatment on some properties of carbon nanotubes

Carbon nanotubes (CNTs) were synthesized using a chemical vapour deposition (CVD) method. The properties of CNTs before and after vacuum annealing treatment were studied using scanning electron microscopy (SEM), scanning tunneling microscopy/spectroscopy (STM/STS) and thermogravimetric analysis (TG). Field emission characteristics of the raw and vacuum heated (up to 650°C) carbon nanotube films (CNTFs) were measured in a diode system. Emissive properties of the CNTFs depend on an annealing process during which structural changes in the nanotube walls take place. The structural changes, related to saturation of dangling bonds, influence a rate of oxidation process and also improve the emissive field properties.     

单壁碳纳米管对C-C键水解酶BphD的固定化性能

采用修饰与未修饰单壁碳纳米管固定C-C键水解酶BphD,并对固定化酶的相对活性、稳定性、重复使用性进行了考察.结果表明,未修饰单壁碳纳米管固定的BphD相对活性为游离态的52.5%,其热稳定性和在变性剂中的稳定性均有所提高,且重复使用10次仍可保持初始活力的90%.修饰单壁碳纳米管固定的BphD相对活性可达99.7%,但其稳定性没有明显提高.同源模建及分子对接分析结果显示,未修饰的单壁碳纳米管对BphD亚基之间的联系可能存在干扰作用,从而对其活性产生影响.     

Endohedral and exohedral complexes of 1-benzene with carbon nanotubes and high-density assembly of multiple benzenes inside of a carbon nanotube

The 1-benzene was put on the inside and surface of various armchair (n, n) (n = 6-12, 14) and zigzag (n, 0) (n = 10-17, 20) nanotubes of different diameters. The binding structure, binding energy, and effects on binding energy were analyzed. All interaction structures and the properties of the assembled complexes were investigated via density functional tight-binding method. Furthermore, we put multiple benzene molecules (2-18 benzenes) inside the armchair (10, 10), (9, 9), and (8, 8) carbon nanotubes (CNTs) and found that two types of structures were formed for the endohedral complexes of multiple benzenes-spiral symmetrical polygon and criss-crossed types, respectively. The detail of the binding energies and structure properties for (10, 10)/kBen (k = 1-6, 18), (9, 9)/kBen (k = 4, 5, 15), and (8, 8)/kBen (k = 1-8) were discussed. Furthermore, the HOMOs and LUMOs of the representative complexes were also studied to illustrate the interactions. This article offers a new assembly method to prepare a high density of benzenes inside of CNTs and offers a method for benzene adsorption by CNT.     

吡硫醇在单壁碳纳米管修饰电极上电化学行为的研究

研究了吡硫醇在单壁碳纳米管修饰电极上的电化学行为,提出了一种检测吡硫醇的电化学方法.在0.1 mol/L的NaAc-HAc(pH 4.0)缓冲溶液中,吡硫醇在单壁碳纳米管修饰电极上出现一灵敏的氧化峰,峰电位位于0094 V处.与裸玻碳电极相比,单壁碳纳米管修饰电极显著提高了吡硫醇的氧化峰电流.在最佳实验条件下,吡硫醇浓度在9.9×10~(-6)～5.7×10~(-4) mol/L范围内与峰电流呈良好的线性关系,检出限为2.98×10~(-7) mol/L.吡硫醇在单壁碳纳米管修饰电极上的氧化过程受吸附控制,为1电子2质子的过程.     

Tuning periodicity of polymer-decorated carbon nanotubes

Carbon nanotube (CNT) is one of the most extensively investigated nanomaterials. Patterning soft matter such as liquid crystals and polymers on CNTs could potentially enable various applications for CNTs. We have demonstrated that controlled polymer crystallization using CNTs as the 1D nucleation sites can lead to periodically functionalized CNTs. Here we show that selected crystalline block copolymers can be periodically decorated along CNTs. This facile technique opens a gateway to periodic patterning on 1-D nanomaterials.     

The binding of single-stranded DNA and PNA to single-walled carbon nanotubes probed by flow linear dichroism

The binding of single-stranded DNAs and a neutral DNA analogue (peptide nucleic acid, PNA) to single-walled carbon nanotubes in solution phase has been probed by absorbance spectroscopy and linear dichroism. The nanotubes are solubilised by aqueous sodium dodecyl sulfate, in which the nucleic acids also dissolve. The linear dichroism (LD) of the nanotubes, when subtracted from that due to the nanotubes/nucleic acid samples, gives the LD of the bound nucleic acid. The binding of the single-stranded DNA to the single-walled nanotubes is quite different from that previously observed for double-stranded DNA. It is likely that the nucleic acid bases lie flat on the nanotube surface with the backbone wrapping round the nanotube at an oblique angle in the region of 45 degrees . The net effect is like beads on a string. The base orientation with the single-stranded PNA is inverted with respect to that of the single-stranded DNA, as shown by their oppositely signed LD signals.     

Direct electron transfer of hemoglobin on dihexadecyl hydrogen phosphate/single-wall carbon nanotubes film modified Au electrode and its interaction with taxol

Direct electrochemistry of hemoglobin (Hb) immobilized on the dihexadecyl hydrogen phosphate (DHP)/single-wall carbon nanotubes (SWNTs) film modified Au electrode is investigated. The immobilized Hb displays a couple of stable and well-defined redox peaks, whose formal potential (E ⁰) is −0.434 V (SCE) in a phosphate buffer solution of pH 7.0. The formal potential of the heme Fe(III)/Fe(II) couple shifts negatively linearly with increased pH with a slope of −42.3 mV/pH, denoting that one electron transfer accompanies single proton transportation. Both SWNTs and DHP can accelerate the electron transfer between Hb and the electrode. Using DHP/Hb/SWNTs-film-modified Au electrode, the interaction between Hb and taxol is investigated. The voltammetric response of Hb decreases with increasing concentration of taxol. The peak currents decreases proportionally to the taxol concentration at 1.4 × 10⁻⁵ to 1.3 × 10⁻⁴ M, the linear regression equation being Δi (A) = 2.9603 − 0.4225 c_taxol (M), with a correlation coefficient (r) 0.9985, and the detection limit 6.95 × 10⁻⁶ M (signal-to-noise ratio of three). Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 7, pp. 801–807. The text was submitted by the authors in English.     

Selective adsorption of proteins on single-wall carbon nanotubes by using a protective surfactant

The dispersion of highly hydrophobic carbon materials such as carbon nanotubes in biological media is a challenging issue. Indeed, the nonspecific adsorption of proteins occurs readily when the nanotubes are introduced in biological media; therefore, a methodology to control adsorption is in high demand. To address this issue, we developed a bifunctional linker derived from pyrene that selectively enables or prevents the adsorption of proteins on single-wall carbon nanotubes (SWNTs). We demonstrated that it is possible to decrease or completely suppress the adsorption of proteins on the nanotube sidewall by using proper functionalization (either covalent or noncovalent). By subsequently activating the functional groups on the nanotube derivatives, protein adsorption can be recovered and, therefore, controlled. Our approach is simple, straightforward, and potentially suitable for other biomolecules that contain thio or amino groups available for coupling.     

Bulk polymerized polystyrene in the presence of multiwalled carbon nanotubes

The in situ bulk polymerization method was applied to synthesize composites of multiwalled carbon nanotubes (MWNTs) and polystyrene (PS) under ultrasonication to open π-bonds in the MWNTs. Morphology of the composite products was studied by both scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Thermal properties and molecular weight of the PS synthesized in the presence of the MWNTs were examined by thermogravimetric analysis (TGA) and gel permeation chromatography (GPC), respectively. The MWNTs were observed to play an important role as initiator consumers during the polymerization reaction. Electrical conductivity of a film-type sample of the PS/MWNT nanocomposite was found to increase with increased amount of MWNTs added, following the percolation theory.     

Preparation of micelle-encapsulated single-wall and multi-wall carbon nanotubes with amphiphilic hyperbranched polymer

The hyperbranched polyester (Boltorn^TM H20) was modified by maleic anhydride and then polystyrene (H20-MAh-PSt) to form amphiphilic micelles in water. The single-wall and multi-wall carbon nanotubes (SWCNTs and MWCNTs, respectively) were encapsulated in the formed micelles through non-covalent interactions. The formed structures were confirmed by FTIR, NMR, GPC, and XPS analysis. The dispersion and aggregation behaviors were observed by TEM and UV-vis and Raman spectroscopic analysis. The results showed that the dispersion performance of the obtained micelle-encapsulated carbon nanotubes in water was greatly improved compared to the pure carbon nanotubes. From the TEM observation, the individual SWCNT structure and the uniform polymer coating around the surface of SWCNT were seen after crosslinking. The Raman spectroscopic measurements also demonstrated that for the crosslinked samples, no effect occurred associated with concentration-dependent carbon nanotube aggregation.     

吲哚美辛在单壁碳纳米管修饰电极上的电化学行为

运用伏安法研究了吲哚美辛在单壁碳纳米管修饰电极上的电化学行为.在0.1 mol/L HAc-NaAc缓冲溶液(pH 4.5)中,吲哚美辛于0.91 V (vs.SCE)电位处有一个峰形很好的氧化峰.与裸玻碳电极相比,吲哚美辛在修饰电极上的电位正移了约30 mV,峰电流增加了近10倍,表明该修饰电极对吲哚美辛有较强的电催化作用.搅拌条件下开路富集2 min,氧化峰电流与吲哚美辛在5.5×10-7～1.1×10-5 mol/L浓度范围内呈良好的线性关系,检出限为1.1×10-7 mol/L.该方法可用于药剂中吲哚美辛的分析.     

XPS study of interactions between linear carbon chains and colloidal Au nanoparticles

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溶剂热合成碳纳米管

自1991年Iijima发现碳纳米管以来,碳纳米管因其独特的结构和物理化学性质而成为人们的研究热点。     

A review of linear carbon chains

Linear carbon chains (LCCs) are a one-dimensional sp¹-hybridized allotrope of carbon. LCCs are extremely unstable: The longer the LCCs, the less stable the materials. Thus, it is a big challenge to synthesize long LCCs. Although the research on the short LCCs, e.g., polyynes, can be traced back to the 18^th, LCCs are still not well-known compared to other allotropes of carbon, e.g., fullerenes, carbon nanotubes and graphene. Therefore, introducing recent progress on LCCs is of great significance to draw more attention in the community of nanocarbons as well as nanomaterials in general. Theoretically, various excellent properties have been predicted. Experimentally, LCCs with different length in many kinds of forms have been successfully synthesized. In this review, we summarized recent studies of polyynic LCCs from both theoretical and experimental aspects. Also, perspectives are highlighted to point out the further investigations of the materials.     

Supramolecular hybrids of [60]fullerene and single-wall carbon nanotubes

Noncovalent interactions between purified HiPCO single-wall carbon nanotubes (SWNT) and a [60]fullerene-pyrene dyad, synthesized through a regioselective double-cyclopropanation process, produce stable suspensions in which the tubes are very well dispersed, as evidenced by microscopy characterization. Cyclic voltammetry experiments and photophysical characterization of the suspensions in organic solvents are all indicative of sizeable interactions of the pyrene moiety with the SWNT and, therefore, of the prevalence in solution of [60]fullerene-pyreneSWNT hybrids.     

Highly selective synthesis of single-walled carbon nanotubes from methane in a coupled Downer-turbulent fluidized-bed reactor

For the synthesis of single-walled carbon nanotubes (SWCNTs) from CH₄ over a Fe/MgO catalyst, we proposed a coupled Downer-turbulent fluidized-bed (TFB) reactor to enhance the selectivity and yield (or production rate) of SWCNTs. By controlling a very short catalyst residence time (1–3 s) in the Downer, only part of Fe oxides can be reduced to form Fe nano particles (NPs) available for the growth of SWCNTs. The percentage of unreduced Fe oxides increased and the yield of SWCNTs decreased accordingly with the increase of catalyst feeding rate in Downer. SWCNTs were preferentially grown on the catalyst surface and inhibited the sintering of the Fe crystallites which would be formed thereafter in the downstream TFB, evidenced by TEM, Raman and TGA. The coupled Downer-turbulent fluidized-bed reactor technology allowed higher selectivity and higher production rate of SWCNTs as compared to TFB alone.