Boron-doped Single-walled Carbon Nanotubes Research Articles

Topology of boron substitutional defects in single-walled carbon nanotubes: A first-principles study

This is a theoretical study of boron-doped single-walled carbon nanotubes. The same topology of primitive nanodomains, located at different positions on single-walled carbon nanotubes, leads to different electronic band structures. We propose a ϕ term. Density functional theory was corrected for van der Waals interactions and used to carry out the periodic boundary condition geometry optimization, where boron formed the topologies of primitive nanodomains. The calculated bulk structure and local structure spectroscopic parameters can be used for comparison with experimental results to confirm the theoretical models.

Boron-Doped Single-Walled Carbon Nanotubes with Enhanced Thermoelectric Power Factor for Flexible Thermoelectric Devices

We report a detailed experimental and theoretical study on thermoelectric properties of boron-doped single-walled carbon nanotubes (B-SWCNTs), which are versatile building blocks of flexible thermo...

Boron Doping of SWCNTs as a Way to Enhance the Thermoelectric Properties of Melt-Mixed Polypropylene/SWCNT Composites

Composites based on the matrix polymer polypropylene (PP) filled with single-walled carbon nanotubes (SWCNTs) and boron-doped SWCNTs (B-SWCNTs) were prepared by melt-mixing to analyze the influence of boron doping of SWCNTs on the thermoelectric properties of these nanocomposites. It was found that besides a significantly higher Seebeck coefficient of B-SWCNT films and powder packages, the values for B-SWCNT incorporated in PP were higher than those for SWCNTs. Due to the higher electrical conductivity and the higher Seebeck coefficients of B-SWCNTs, the power factor (PF) and the figure of merit (ZT) were also higher for the PP/B-SWCNT composites. The highest value achieved in this study was a Seebeck coefficient of 59.7 µV/K for PP with 0.5 wt% B-SWCNT compared to 47.9 µV/K for SWCNTs at the same filling level. The highest PF was 0.78 µW/(m·K2) for PP with 7.5 wt% B-SWCNT. SWCNT macro- and microdispersions were found to be similar in both composite types, as was the very low electrical percolation threshold between 0.075 and 0.1 wt% SWCNT. At loadings between 0.5 and 2.0 wt%, B-SWCNT-based composites have one order of magnitude higher electrical conductivity than those based on SWCNT. The crystallization behavior of PP is more strongly influenced by B-SWCNTs since their composites have higher crystallization temperatures than composites with SWCNTs at a comparable degree of crystallinity. Boron doping of SWCNTs is therefore a suitable way to improve the electrical and thermoelectric properties of composites.

Ruthenium decorated boron-doped carbon nanotube for hydrogen storage: A first-principle study

In this paper, the adsorption of molecular hydrogen on Ruthenium (Ru) decorated boron-doped single-walled carbon nanotube (CNT) is theoretically studied, based on the density-functional theory (DFT). The projected density of states (PDOS) and charge density difference are computed, and Mulliken population analysis is conducted to investigate the molecular hydrogen adsorption ability of a boron-doped CNT (BCNT) system and a pure CNT system. As for the pure CNT system, a single Ru atom can absorb up to four H2 molecules with a binding energy of −1.057eV/H2; and for the boron-doped CNT system, the binding energy of H2 molecules increases to −1.151eV/H2 and it displays much higher binding energy of Ru with the increase of 21.19%. This implies that the BCNT system is more stable and has better ability to adsorb hydrogen molecules. The enhanced ability to adsorb H2 molecules implies that Ru decorated BCNT may be a useful and promising nanomaterial for hydrogen energy storage.

Rapidly self-heating shape memory polyurethane nanocomposite with boron-doped single-walled carbon nanotubes using near-infrared laser

In this study, boron-doped single-walled carbon nanotubes (SWCNTs) were synthesized by high-temperature heat treatment (1300 °C) with a boric acid precursor and SWCNTs instead of the conventional chemical doping process. Then, these boron-doped single-walled carbon nanotubes (B-SWCNTs) were added to polyurethane to prepare polyurethane nanocomposites having excellent thermal and mechanical properties. Changes in properties that occurred due to structural changes inside the composite were investigated as the added amount of nanofiller was increased. In particular, a near-infrared (NIR) laser (808 nm) was directly irradiated on the nanocomposite film to induce photothermal properties on the surface of the B-SWCNTs. In the case of the PU nanocomposite film with a filler content of 3 wt%, a self-heating film material that rapidly heated to 250 °C within 10 s was developed. The newly developed material can be applied to electronic devices and products as a heat-generating coating material, de-icing of airplane, a heat sink, for bio-sensing, etc., using a moulding process.

Very high boron-doping on single-walled carbon nanotubes from a solid precursor

Despite the tremendous progress on the use of chemical vapor deposition as widespread method for the synthesis of pristine carbon nanotubes, introducing substitutional heteroatoms like boron on the carbon sites imposes several difficulties. The reported precursors used for boron-doped single-walled carbon nanotubes have exclusively been liquid based. Here we show that the use of solid sodium tetraphenylborate, which contains both carbon and boron in its stoichiometry, do not only effectively circumvent the experimental problems reported so far in the synthesis of these materials, but it enables the incorporation of up to 27.5 at.% of boron atoms in the samples as-grown. This percentage corresponds to a total B content, not to substitutional B configuration exclusively. Spectral deconvolution of the B1s signal suggests a 13 at.% of graphitic bonding environment of B within the samples. We propose an alternative method capable of producing B-doped singled-walled tubes with a small diameter distribution (∼0.89 nm to ∼1.9 nm) within a ∼60 °C temperature window.

Electronic properties and gas adsorption behaviour of pristine, silicon-, and boron-doped (8, 0) single-walled carbon nanotube: A first principles study

Carbon nanotubes (CNTs) have received enormous attention due to their fascinating properties to be used in various applications including electronics, sensing, energy storage and conversion. The first principles calculations within density functional theory (DFT) have been carried out in order to investigate the structural, electronic and optical properties of un-doped and doped CNT nanostructures. O2, CO2, and CH3OH have been chosen as gas molecules to study the adsorption properties based on zigzag (8,0) SWCNTs. The results demonstrate that the adsorption of O2, CO2, and CH3OH gas molecules on pristine, Si-doped and B-doped SWCNTs are either physisorption or chemisorption. Moreover, the electronic properties indicating SWCNT shows significant improvement toward gas adsorption which provides the impact of selecting the best gas sensor materials towards detecting gas molecule. Therefore, these pristine, Si-, and B-doped SWCNTs can be considered to be very good potential candidates for sensing application.

Water-Induced Interactions between Boron-Doped Carbon Nanotubes

Molecular dynamics (MD) simulations are used to investigate the hydration, the water-induced interactions, and the dispersion behavior of boron-doped single-walled carbon nanotubes (B-CNTs) within ...

First-Principles Studies of the Activation of Oxygen Molecule and Its Role in Partial Oxidation of Methane on Boron-Doped Single-Walled Carbon Nanotubes

The nanostructured carbon materials have been widely tested as catalyst in a number of chemical reactions. The oxygen functional groups on nanostructured carbon catalyst are believed to be the active sites, for example, in the oxidative dehydrogenation reaction of hydrocarbons. However, the doping is one of the effective ways to tune the properties of nanostructured carbon materials. It will be important to examine the effect of doping on the catalytic properties of oxygen molecule on nanostructured carbon materials. In current work, the dissociation of the oxygen molecule on the boron-doped single-walled carbon nanotube (BSWCNT) and their catalytic properties in the partial oxidation of methane to formaldehyde are investigated by using first-principles calculations. Both defect-free BSWCNT and defective BSWCNT with a monovacancy are studied, and the comparisons between them are made. BSWCNT demonstrates a good ability for the dissociation of oxygen molecule. The favorable binding sites for the dissociate...

Electrical transport properties of boron-doped single-walled carbon nanotubes

The transport properties of B-doped single-walled carbon nanotubes (SWNTs) are studied from both experimental and theoretical standpoints. Experimentally, it is found that the semiconducting behavior of SWNTs is drastically changed after B-doping, and the unusual abrupt current drops are observed at low temperatures, which may imply the possibility of superconducting transition in B-doped SWNTs. Using the density-functional tight-binding calculation, it is observed that B-doping induces the presence of density of state peaks near the Fermi level which shifts toward the valence band region, showing a clear charge-transfer characteristic, which agrees well with the experimental observations.

On the purification of CVD grown boron doped single-walled carbon nanotubes

In this paper, we report a facile purification method of boron-doped single-walled carbon nanotubes (SWCNTs) produced by high vacuum chemical vapor deposition (HV-CVD). The raw material was doped in situ during growth, with a B content below 0.5 at.%, estimated by means of X-ray photoelectron spectroscopy (XPS). Using ultracentrifugation combined with a mild acid solution pH neutralization, we have proved it is feasible to purify this material, which originally contains synthesis byproducts that differ from the typical catalytic remaining in pristine carbon nanotube samples produced with a similar method. The diameter size and distribution – previous and after purification – have been monitored by multi-frequency Raman spectroscopy.

Photovoltaic devices based on high density boron-doped single-walled carbon nanotube/n-Si heterojunctions

A simple and easily processible photovoltaic device has been developed based on boron-doped single-walled carbon nanotubes (B-SWNTs) and n-type silicon (n-Si) heterojunctions. The SWNTs were substitutionally doped with boron atoms by thermal annealing, in the presence of B2O3. The samples used for these studies were characterized by Raman spectroscopy, thermal gravimetric analysis, transmission electron microscopy, and x-ray photoelectron spectroscopy. The fully functional solar cell devices were fabricated by airbrush deposition that generated uniform B-SWNT films on top of the n-Si substrates. The carbon nanotube films acted as exciton-generation sites, charge collection, and transportation while the heterojunctions formed between B-SWNTs and n-Si acted as charge dissociation centers. The current-voltage characteristics in the absence of light and under illumination, as well as optical transmittance spectrum are reported here. It should be noted that the device fabrication process can be made amenable to scalability by depositing direct and uniform films using airbrushing, inkjet printing, or spin-coating techniques.

Superconductivity in Boron-Doped Carbon Nanotubes

Carbon nanotubes (CNTs), which are one-dimensional (1D) molecular conductors, have attracted considerable attention. However, none of the research has reported on superconductivity (SC) in carrier-doped CNTs. Here, we report on SC with the world’s highest transition temperature (T c) of 12 K in highly uniform thin films of boron-doped single-walled CNTs (B-SWNTs). We clarify correlation of SC with Fermi level tuning with van Hove singularities (VHS) in electronic density of states (DOS) in the SWNT. Moreover, we show fabrication of paper-like thin films consisting of a pseudo two-dimensional network of weakly coupled B-SWNTs (called the Buckypaper) and show an enhancement of the onset T c up to 19 K by applying only a small pressure. The present observations will shed light on the high feasibility of using CNTs as a 1D superconductor and also on the research of 1D electron correlation.

Pressure-induced superconductivity and phonon frequency in paperlike thin films of boron-doped carbon nanotubes

We show formation of paperlike thin films (Buckypaper) consisting of pseudo-two-dimensional network of individual boron-doped single-walled carbon nanotubes (B-SWNTs), by sufficiently dissolving as-grown ropes of SWNTs and densely assembling them on silicon substrate. We find superconducting transition at temperature $({T}_{\text{c}})$ of 8 K under absent pressure and that it can be induced as large as 2.4 times up to 19 K by applying a small pressure of 20 MPa. A significant frequency increase in the radial breathing phonon mode (RBM) is also found with applying pressure in Raman spectrum measurements. Moreover, B-SWNTs with a diameter of 0.6 nm are confirmed in the Buckypaper. These imply the strong correlation of the pressure-induced ${T}_{\text{c}}$ with electron-phonon (RBM) coupling of 0.6-nm-diameter B-SWNTs.

A theoretical study on the effect of intercalating sulfur atom and doping boron atom on the adsorption of hydrogen molecule on (10,0) single-walled carbon nanotubes

Adsorption of molecular hydrogen on single-walled carbon nanotube (SWCNT), sulfur-intercalated SWCNT (S-SWCNT), and boron-doped SWCNT (BSWCNT), have been studied by means of density functional theory (DFT). Two methods KMLYP and local density approximation (LDA) were used to calculate the binding energies. The most stable configuration of H2 on the surface of pristine SWCNT was found to be on the top of a hexagonal at a distance of 3.54 A in good agreement with the value of 3.44 A reported by Han and Lee (Carbon, 2004, 42, 2169). KMLYP binding energies for the most stable configurations in cases of pristine SWCNT, S-SWCNT, and BSWCNT were found to be −2.2 kJ mol−1, −3.5 kJ mol−1, and −3.5 kJ mol−1, respectively, while LDA binding energies were found to be −8.8 kJ mol−1, −9.7 kJ mol−1, and −4.1 kJ mol−1, respectively. Increasing the polarizability of hydrogen molecule due to the presence of sulfur in sulfur intercalated SWCNT caused changes in the character of its bonding to sulfur atom and affected the binding energy. In H2-BSWCNT system, stronger charge transfer caused stronger interaction between H2 and BSWCNT to result a higher binding energy relative to the binding energy for H2-SWCNT.

Pressure-induced superconductivity in boron-doped Buckypapers

We show creation of paperlike thin film (Buckypaper) consisting of pseudo-two-dimensional network of boron-doped single-walled carbon nanotubes (B-SWNTs) within weakly intertube van der Waals coupling (IVDWC) state. It was formed by sufficiently dissolving as-grown ropes of B-SWNTs and densely assembling them on silicon substrate. We find that superconducting transition temperature (Tc) of 8 K under absent pressure can be induced up to 19 K by applying a small pressure to the film and that a frequency in the radial breathing phonon drastically increases with applying pressure. Discussion about IVDWC and distribution of B-SWNTs diameter imply the strong correlation.

Transition-Metal Strings Templated on Boron-Doped Carbon Nanotubes: A DFT Investigation

The binding nature, magnetic, and electronic properties of transition-metal (TM) monatomic chains anchored on boron-doped single-walled carbon nanotubes (B-SWCNTs) are studied using density-functional theory. The TM systems studied here include Au, Pt, Ru, Pd, Ag, Co, Ni, Cu, W, and Ti, which are well-known for their technical importance. In conjunction, prototype semiconducting SWCNT(8,0) and metallic SWCNT(6,6) were chosen to model the general features of B-doped SWCNTs. It is found that the TM-strings exhibit well-defined covalent bonds with the boron-doped SWCNTs, in contrast to the pristine SWCNTs. The TM-string/B-SWCNT composites exhibit high stability and unexpected electronic properties, which are relevant to applications in nanoelectronics, spintronics, nanocatalysis, and sensor devices.

Meissner effect in films of ropes of boron-doped single-walled carbon nanotubes; Correlation with applied pressure and boron-doped multi-walled nanotubes

Superconductivity in carbon nanotubes (CNTs) is attracting considerable attention. Recently, we have reported successful boron doping into single-walled CNTs (SWNTs) and also revealed its correlation with superconductivity. In the present study, we report results of pressure-applied magnetization measurements in films consisting of ropes of boron-doped SWNTs. It reveals that Tc and magnitude for Meissner effect is mostly independent of applied pressure, while magnitude of graphite diamagnetism drastically increases as pressure increases. We also report result of resistance measurements in the samples and also correlation of boron doped SWNTs with multi-walled CNTs, in which we reported superconductivity previously.

Interaction between glycine/glycine radicals and intrinsic/boron-doped (8,0) single-walled carbon nanotubes: a density functional theory study.

The adsorptions of a glycine molecule as well as dehydrogenated radicals on the side walls of both intrinsic and boron-doped (B-doped) single-walled (8,0) carbon nanotubes (SWCNTs) were investigated by a density functional theory. A glycine molecule tends to physically adsorb on intrinsic SWCNTs yet chemically adsorb on B-doped SWCNTs as a result of a somewhat chemical bond between the electron-rich nitrogen atom of the glycine molecule and the electron-scarce boron atom of the doped SWCNT. Opposite to the previous report (J. Phys. Chem. B 2006, 110, 6048-6050), it is found in the present study that both the N-centered and C-centered glycine radicals can form quite stable complexes with intrinsic as well as B-doped (8,0) SWCNTs. When the B-doped SWCNT interacts with glycine radicals, although there is a competition between B and the neighbor C in the nanotube axis direction, glycine radicals preferentially bind to the C site. The encapsulations of a glycine molecule into SWCNTs with various diameters are also discussed. We find that the encapsulation process is endothermic for (8,0) and (9,0) SWCNTs, while it is exothermic for (10,0) SWCNTs, indicating that the critical diameter of the zigzag SWCNT for the encapsulation is 7.83 A, the diameter of (10,0).

Transparent Boron-Doped Carbon Nanotube Films

We report results of studies on the sheet resistance and optical transmission of thin films of boron-doped single-walled carbon nanotubes (SWNTs). Boron doping was carried out by exposure of SWNTs to B 2O 3 and NH 3 at 900 degrees C and 1-3 atom % boron was found in the SWNT bundles via electron energy loss spectroscopy (EELS). Boron doping was found to downshift the positions of the optical absorption bands associated with the van Hove singularities (E 11 (s) E 22 (s) and E 11 (m)) by approximately 30 meV relative to their positions in acid-treated and annealed SWNTs. Raman spectroscopy, EELS, and optical data are consistent with the picture that a few atom % boron has been substituted for carbon in the sp (2) framework of SWNTs. Finally, our results show that boron doping does not significantly affect the optical transmittance in the visible region. However, boron doping lowers the sheet resistance by approximately 30% relative to pristine SWNT films from the same batch. Boron-doped SWNT may provide a better approach to touch-screen technology.