Substitutional doping of BN nanotube by transition metal: A density functional theory simulation

A new strategy for making a sensitive sensor for aspirin drug: first-principles investigations by using pure and metal-doped BN nano-heterostructures

The present study used the DFT method to investigate aspirin's intermolecular interactions with boron nitride (BN) nanotubes modified with aluminum, gallium, and zinc. Our experiments obtained adsorption energy of -40.4 kJ/mol for aspirin on BN nanotubes. By doping each of the above metals on the surface of the BN nanotube, the aspirin adsorption energy increased dramatically. For BN nanotubes doped with Al, Ga, and Zn, this energy was -255, -251, and -250 kJ/mol. Thermodynamic analyses proved that all surface adsorptions are exothermic and spontaneous. Nanotubes' electronic structures and dipole moments have been examined following aspirin adsorption. In addition, AIM analysis has been performed for all systems in order to understand how the links were formed. According to the obtained results, BN nanotubes doped with metals, as mentioned previously, have a very high electron sensitivity to aspirin. These nanotubes can therefore be used to manufacture aspirin-sensitive electrochemical sensors.Communicated by Ramaswamy H. Sarma.

Enhanced Catalytic Activity of Boron Nitride Nanotubes by Encapsulation of Nickel Wire Toward O2 Activation and CO Oxidation: A Theoretical Study

Perfect boron nitride (BN) nanotubes are chemically inert, and hardly considered as catalysts. Nevertheless, metal wire encapsulated BN nanotubes show extraordinarily high chemical activity. We report nickel (Ni) nanowire encapsulated BN(8.0) and BN(9.0) nanotubes toward O2 activation and CO oxidization on the basis of first-principles calculations. Our results suggest that Ni wire encapsulated BN(8.0) and BN(9.0) nanotubes can easily adsorb and activate O2 molecules to form peroxo or superoxo species exothermically. Meanwhile, superoxo species are ready to react with CO molecules forming OCOO intermediate state and finally yielding CO2 molecules. Meanwhile, the rate-limiting step barrier is only 0.637 eV, implying excellent performance for CO oxidation on Ni nanowire encapsulated BN nanotubes. Furthermore, encapsulation of nickel wire improves the catalytic activity of BN nanotubes by facilitating electron transfer from Ni wire to BN nanotubes, which facilitates the adsorption of highly electronegative O2 molecules and subsequent CO oxidation. This study provides a practical and efficient strategy for activating O2 on a metal encapsulated BN nanotube toward CO oxidation.

Hybrid Ni-Boron Nitride Nanotube Magnetic Semiconductor-A New Material for Spintronics

Here, we report the presence of ferromagnetism in hybrid nickel-boron nitride nanotubes (BNNTs) with an ordered structure, synthesized by chemical vapor deposition using elemental boron, nickel oxide as the catalyst, and ammonia gas as the source for nitrogen. In previous studies, the nanotubes were synthesized with two metal oxide catalysts, whereas here, only a single catalyst was used. The nanotube's structure was determined by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. Purity of the nanotubes synthesized at 1150 °C was exceptional and this was determined by Raman spectroscopy. The average diameter of the nanotubes was 63 nm. Based on the magnetic studies carried out, it can be confirmed that the synthesized hybrid material is ferromagnetic at room temperature. Cyclic voltammetry was carried out to confirm the dielectric nature of the nanotubes. These materials could pave ways to nanoscale devices. The well-known thermal stability of BNNTs would play a vital role in preventing thermal failures in such small-scale devices where overheating is a major concern. The presence of semiconducting and magnetic properties in a single material could be confirmed, which might be highly significant in the field of spintronics.

Interaction of Boron Nitride Nanotubes with Aluminium: A Computational Study

The interaction of boron nitride nanotubes (BNNTs) with Al has been investigated by means of quantum chemical calculations. Two model structures were used: a BNNT adsorbing a four atom Al₄ cluster, and a BNNT adsorbed on Al surfaces of different crystallographic orientations. The BNNTs were modeled as: (i) pristine, and (ii) having a boron (B-) or a nitrogen (N-) vacancy defect. The results indicated that the trends in binding energy for Al₄ clusters were, similar to those of the adsorption on Al surfaces, while the Al surface orientation has a limited effect. In all cases, the calculations reveal that Al binding to a BNNT was strongly enhanced at a defect site on the BNNT surface. This higher binding was accompanied by a significant distortion of the Al cluster or the Al lattice near the respective vacancy. In case of a B-vacancy, insertion of an Al atom into the defect of the BNNT lattice, was observed. The calculations suggest that in the Al/BNNT metal matrix composites, a defect-free BNNT experiences a weak binding interaction with the Al matrix and tthe commonly observed formation of AlN and AlB₂ was due to N- or B-vacancy defects within the BNNTs.

XH3 (X=P or N) Adsorption on Pristine, Pt-Doped and Vacancy-Defective (8,8) Boron Nitride Nanotubes: DFT Calculations

The adsorption energies (E ad), interaction distances, changes of geometric and electronic structures of XH3 (X=P or N) gas molecule adsorption on pristine, platinum (Pt) doped and vacancy-defected single-walled (8,8) boron nitride nanotubes (BNNTs) have been calculated using the density functional theory (DFT). The effect of the Pt doping on B and N sites (PtB,N-doped) and the B and N vacancy defects (VB,N-defected BNNT) on the sensing behavior of pristine (8,8) BNNTs toward PH3 and NH3 gases have been examined. According to the obtained results, PH3 and NH3 molecules were more likely to be absorbed on the PtB,N-doped and VN-defected BNNT with relatively higher E ad compared with the pristine and VB-defected BNNTs. Therefore the order of the obtained E ad were PtB-doped BNNT/NH3>PtB-doped BNNT/PH3>PtN-doped BNNT/NH3>PtN-doped BNNT/PH3 for the PtB,N-doped BNNTs, and VN-defected BNNT/NH3>VN-defected BNNT/PH3>VB-defected BNNT/NH3>VB-defected BNNT/PH3 for the VB , N-defected BNNTs systems. The partial density of states (PDOS) of the adsorption systems indicated the strong interaction between the adsorbed PH3 and NH3 molecules and the substrates, i.e. PtB,N-doped BNNT and VN-defected BNNT. Therefore, it can concluded that the PtB,N-doped and VN-defected BNNTs have potential applicability in the gas-sensing detection of PH3 and NH3 with good sensitivity.

DFT study of the adsorption of 2,3,7,8-tetrachlorodibenzo-p-dioxin on pristine and Ni-doped boron nitride nanotubes

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are highly toxic to humans and the environment. Developing efficient methods to detect or remove these pollutants is particularly important and urgent. Boron nitride nanotubes (BNNTs) with low dimension and high surface-to-volume ratio might be one of promising materials for the adsorption of PCDD/Fs. Here we present a density functional theory (DFT) study on the interaction of the pristine and Ni doped (8,0) single-walled BNNTs with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic congener among PCDD/F family. The calculated results show that the pristine BNNT intrinsically interacts with TCDD via physisorption with π-π stacking interaction, in contrast, the Ni-doped BNNT presents much higher reactivities toward TCDD. The impurity Ni atom plays a crucial role for capturing TCDD molecule. We also find that the Ni doping introduces the local electronic states within the band gap of the BNNT and induces magnetism in the doped systems. The present results are expected to provide useful guidance for the potential application of BNNTs as adsorption materials for detecting or removing dioxin pollutants.

Boron nitride nanotubes for spintronics

With the end of Moore's law in sight, researchers are in search of an alternative approach to manipulate information. Spintronics or spin-based electronics, which uses the spin state of electrons to store, process and communicate information, offers exciting opportunities to sustain the current growth in the information industry. For example, the discovery of the giant magneto resistance (GMR) effect, which provides the foundation behind modern high density data storage devices, is an important success story of spintronics; GMR-based sensors have wide applications, ranging from automotive industry to biology. In recent years, with the tremendous progress in nanotechnology, spintronics has crossed the boundary of conventional, all metallic, solid state multi-layered structures to reach a new frontier, where nanostructures provide a pathway for the spin-carriers. Different materials such as organic and inorganic nanostructures are explored for possible applications in spintronics. In this short review, we focus on the boron nitride nanotube (BNNT), which has recently been explored for possible applications in spintronics. Unlike many organic materials, BNNTs offer higher thermal stability and higher resistance to oxidation. It has been reported that the metal-free fluorinated BNNT exhibits long range ferromagnetic spin ordering, which is stable at a temperature much higher than room temperature. Due to their large band gap, BNNTs are also explored as a tunnel magneto resistance device. In addition, the F-BNNT has recently been predicted as an ideal spin-filter. The purpose of this review is to highlight these recent progresses so that a concerted effort by both experimentalists and theorists can be carried out in the future to realize the true potential of BNNT-based spintronics.