Defective Boron Nitride Nanotubes Research Articles

Electrocatalytic CO2 conversion on boron nitride nanotubes by metal single-atom engineering

Atomically dispersed single metal on defective boron nitride nanotubes (BNNTs) show promising potential for CO2 electrocatalytic reduction reaction (CO2ERR). Using density functional theory calculations, we explore the CO2ERR mechanism on single-atom catalysts (SACs) supported on BNNTs as well as assess their electrocatalytic performance of these catalysts. Boron or nitrogen vacancies in BNNTs are doped with palladium, platinum, or rhodium atoms to form three-coordinated metal centers, denoted as M@BNNT-V (M = Pt, Rh, Pd; V = B vacancy or N vacancy). Pt@BNNT with boron vacancies (Pt@BNNT-Bvac) demonstrates a tendency to facilitate multi-electron reduction processes leading to the formation of complex molecules such as CH2O, CH3OH, and CH4 with a limiting potential (UL) of −0.36 V. Conversely, Rh@BNNT-Bvac and Pd@BNWNT-Bvac show significantly lower limiting potentials of −0.06 V and −0.12 V, respectively, for the reduction to formic acid (HCOOH), with Rh@BNNT-Bvac exhibiting enhanced activity and selectivity. Additionally, the deep reduction to other hydrocarbons or oxygenates, which typically requires potentials of −0.72 V and −0.60 V, appears less likely on both Rh and Pd doped BNNT-Bvac, further delineating the nuanced performance differences induced by metal type and coordination environment within the BNNT structure.

Transition metal doped into defective boron nitride nanotubes for CO2RR: Regulation of catalytic activity and mechanism by curvature effect

Utilizing electrochemical CO2 reduction reaction (CO2RR) to synthesize chemical fuels is an effective strategy to alleviate environmental pollution and energy crisis. In this work, a series of single transition metal atoms (TM = Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd) are doped into boron nitride nanotubes (BNNTs) of BN divacancy defect with different curvature parameters, which are named as TM-DVBNNT(n, n), and their CO2RR catalytic performance is systematically studied by density functional theory (DFT) methods. To begin with, the calculation results of formation energy and dissolution potential show that all TM-DVBNNT(n, n) have good thermodynamic and electrochemical stability. Secondly, after calculation of Gibbs free energy, Mn-, Fe-, Ru-, and Rh-DVBNNT(5, 5) have good catalytic performance with the corresponding limiting potential (UL) values of −0.43, −0.40, −0.27, and −0.50 V, respectively. Based on this, we further investigate the influence of curvature on the stability, activity, and mechanism of Ru-DVBNNT(n, n) with the highest activity. It is worth noting that as the diameter of Ru-DVBNNT(n, n) continues to increase, their stability and activity also continue to enhance, and Ru-DVBNNT(8, 8) with the largest diameter is expected to become the best performing CO2RR electrocatalyst with the UL value of −0.16 V. Besides, for Ru-DVBNNT(3, 3) and Ru-DVBNNT(4, 4), their final product is HCOOH. In contrast, the CH4 product is more inclined to form on Ru-DVBNNTs with chiral indexes of (5, 5), (6, 6), (7, 7), and (8, 8). In summary, this work has laid a solid theoretical foundation for future experimental design of nanotube structures.

Pristine and vacancy defective boron nitride nanotubes absorb deep eutectic solvents

Density functional theory (DFT) calculations are employed to evaluate the intermolecular interactions between four deep eutectic solvents (DESs) and pristine and defective boron nitride nanotubes. DESs spontaneously adsorb onto the nanotubes through van der Waals (vdW) interactions and charge transfer occurs from the DESs to the nanotubes; affinity is far higher for nanotubes with a boron vacancy. Adsorption of DESs onto boron nitride is stronger than onto carbon nanotubes. DES incorporating benzoic acid show far stronger interactions with the surfaces due to possible π-π interactions, unavailable to the other DES.

Unveiling the Mechanism of Nitrogen Fixation by Single-Atom Catalysts and Dual-Atom Catalysts Anchored on Defective Boron Nitride Nanotubes

Unveiling the Mechanism of Nitrogen Fixation by Single-Atom Catalysts and Dual-Atom Catalysts Anchored on Defective Boron Nitride Nanotubes

High-Throughput computational screening of Single-atom embedded in defective BN nanotube for electrocatalytic nitrogen fixation

The boron nitride nanotubes (BNNTs) have been widely used in various energy applications such as hydrogen storage, gas sensor, carbon dioxide reduction reaction, and so on. Herein, the potential application of BNNT-based catalysts was explored in electrocatalytic nitrogen reduction reaction (eNRR) by density functional theory (DFT) computations. A series of single metal/non-metal atoms (18 transition metals (3d ∼ 5d) and 6 non-metals (B, C, N, Si, P, and As)) supported on the defective BNNT were investigated. Among them, Os-doped (Os@BNNT) single-atom catalyst (SAC) can significantly promote the NRR process, and possess a rather low overpotential (0.31 V), as well as high selectivity over HER competition. The confined Os atom not only serves as an electron donor to supply electrons for NRR, but also acts as a channel for interfacial charge transfer between substrate and NRR intermediates. Moreover, the curved surface of BNNT can decrease the barrier for protonating *NH2 to·NH3. The synergistic collaboration of single-atom Os catalyst and curved surface of BNNT facilitates the NRR process. Our findings open up a new avenue for designing novel nanotube-based materials as eNRR electrocatalysts.

Effect of Stone–Wales defects on the mechanical behavior of boron nitride nanotubes

The transversely isotropic response of pristine as well as defective boron nitride nanotubes (BNNTs) containing Stone–Wales (SW) defects was comprehensively studied via molecular dynamic simulations with a three-body Tersoff force field. The elastic properties and the failure behavior of BNNTs were studied under the transversely isotropic loading conditions, namely uniaxial tension, twisting moment, in-plane shear and in-plane biaxial tension. The effect of chirality, diameter and SW defect density was taken into consideration. The failure mechanism of BNNTs under each loading condition was explained in detail. Our study reveals that the elastic moduli of zigzag BNNTs are higher than for armchair tubes and decrease as the diameter of the tube increases. The effect of SW defects is found to be higher on the elastic properties of smaller diameter BNNTs than for larger diameter tubes, regardless of chirality. The higher defect density reduces the axial Young’s modulus, shear, plane strain bulk and in-plane shear moduli by 11%, 18%, 9% and 7%, respectively. The SW defects affect the (1) longitudinal shear moduli of BNNTs more profoundly irrespective of chirality and (2) the mechanical behavior of zigzag BNNTs stronger compared to armchair ones. It is also found that the mechanical properties of BNNTs are functions of chirality and diameter, especially for small diameter tubes.

N–N bond cleavage and ring expansion at the surface of exchange and substitutional antisite defective boron nitride nanotubes by boron cluster: A density functional theory study

Functionalisation of nitrogen–nitrogen bonds of antisite defective boron nitride nanotubes (BNNTs), including exchange antisite defect which is produced by the rotation of BN bond, and substitutional antisite defect which is formed by substitution of an N with B, is investigated through their interaction with a $$\mathrm{B}^{-}_{6}$$ cluster. The smaller defect formation energies for the substitutional antisite defects indicate that the substitution of an N atom with B atom is easier than rotation of a BN bond. The formation of antisite defects at the edge or near the edges is more favourable than that in the middle of the tubes. When complexation between double ring $$\mathrm{B}^{-}_{6}$$ and nitrogen–nitrogen bonds of antisite defective BNNTs occurs, two-fold coordination, double ring configuration of boron cluster and N–N bond cleavage are seen. In the most stable complex, the $$\mathrm{B}^{-}_{6}$$ pulls apart the B–N bond and becomes an integral part of the tube by expanding the hexagonal BN ring, while in the other BNNT-B6 clusters, double ring $$\mathrm{B}^{-}_{6}$$ acts as a bridge at the top of the decagon. Functionalisation of N–N bonds at the edge or near the edges is more favourable than that in the middle of tubes.

Tunable Single-Photon Emission by Defective Boron-Nitride Nanotubes for High-Precision Force Detection

Boron-nitride nanotubes (BNNTs) hold great potential for electronic, optical, and mechanical applications. By introducing a NBVN defect of removing one nitrogen atom while replacing one boron by nitrogen atom, we examined the use of defective NBVN@BNNTs as a novel type of single-photon emission (SPE) material. Using first-principles calculations to reveal the electronic structures of NBVN@BNNTs, we found that SPE with 1.45–2.29 eV energy can be generated in NBVN@BNNTs with size ranging from (5,0) to (10,0). It is also intriguing to find that their SPE responses are sensitive to the external forces, as indicated by the computed potential energy surfaces and dielectric tensors. Specifically, the (7,0) NBVN@BNNT can serve as an ideal force detector due to its sensitivity and linear response to external force. However, the (5,0) and (6,0) NBVN@BNNTs exhibit insensitive SPE with respect to force applied, and the detection ability of the (8,0), (9,0), and (10,0) NBVN@BNNTs are limited due to the emergence of ne...

Defective boron nitride nanotubes: mechanical properties, electronic structures and failure behaviors

Due to their excellent physical and chemical characteristics, boron nitride nanotubes (BNNTs) are regarded as a complementary addition to carbon nanotubes. Pioneer studies have demonstrated that defects in carbon nanotubes are considered tools for tuning the physical properties of these materials. In the present work, investigation on the mechanical and electronic properties of pristine and defective BNNTs was performed using the density functional theory method. The analysis on the intrinsic strength, stiffness, and failure critical strain of different types of BNNTs was conducted systematically. The computing results showed that the intrinsic strength of BNNTs decreased linearly with the increased Stone–Wales (SW) defect density around the axis. The SW defect density along the axis played a minor role on the changing of mechanical properties of BNNTs. The BNNT with a B vacancy expressed higher intrinsic strength than that of the N vacancy model. The final failure of the pristine BNNTs was due to the fracture of the Type1 bonds under the mechanical strain. Defects like SW or vacancy are served as the initial break site of BNNTs. Applying strain or creating defects are both effective methods for reducing the band gap of BNNTs.

Exploring electronic properties and NO gas sensitivity of Si-doped SW-BNNTs under axial tensile strain

Continuously tuning electronic and magnetic properties of nanomaterials specially by applying an axial tensile strain is a promising route for construction of impending electronic and optoelectronic nanodevices. In the present work, Si doping and axial tensile strain were simultaneously utilized in exploring the structural and electronic properties of single-walled (6,0) SiN, SiB and SiN,B-doped Stone–Wales defective boron nitride nanotubes at M05-2X/6–31+G(d) level. Our findings demonstrate that the Si doping of SW-BNNT destroys the hexagonal BN network and alters the insulating feature of the SW-BNNT. Binding energies of Si-doped SW-BNNTs are estimated to be smaller than un-doped SW-BNNT and decrease continuously upon axial tensile strain. It can be estimated that the Si-doped SW–BNNTs and, in turn, their axial strained forms are more suitable than SW-BNNT one for photoconductivity applications. The unstrained SiN,B has a lower band gap than unstrained SiN and SiB. The results show that the axial tensile strain is not a suitable strategy to improve the conductivity of SiN,B, contrary to those found in SiN and SiB. In the second part of this work, sensitivity of strained and unstrained Si-doped SW-BNNTs toward NO gas is evaluated. The results show that the chemical adsorption of NO is thermodynamically favored in both strained and unstrained forms. Among the Si-doped SW-BNNT–NO complexes, SiN,B-ON1 and SiB-NO2 complexes with adsorption energy of −32.7 and −33.3 kcal mol−1, respectively, are thermodynamically more stable than other complexes. In addition, dispersion-corrected adsorption energies were evaluated at M05-2X-D3/6-31++G(d,p)//M05-2X/6–31+G(d) level of theory. The greatest charge transfer value and change in the band gap upon adsorption was predicted in all complexes. Thus, it is expected that Si-doped SW-BNNT could be a favorable NT for removing and sensing the NO gas.

N2O + SO2 reaction over Si- and C-doped boron nitride nanotubes: A comparative DFT study

Density functional theory calculations are performed to investigate the mechanisms of N2O reduction by SO2 over Si- and C-doped (6,0) boron nitride nanotubes (BNNTs). According to our results, the Si or C adatom can be strongly stabilized over the vacancy defect of the BNNT. The adsorption energy of Si and C atoms over defective BNNT is calculated to be −297.3 and −333.7kcal/mol, respectively, indicating a strong interaction between these dopant atoms and the tube surface. The N2O reduction reaction includes the decomposition of N2O (i.e. N2O→N2+O*), followed by the reduction of O* by SO2 molecule (i.e. SO2+O*→SO3). The calculated energy barrier of the SO2+O*→SO3 reaction on Si- and C-doped BNNTs is 2.4 and 5.4kcal/mol, respectively. Moreover, the effects of tube diameter and length on the N2O reduction are studied in detail. The disproportionation of N2O molecules (2N2O→2N2+O2) over both surfaces needs a quite large activation energy, which indicates the impossibility of this reaction at ambient condition. The results show that both Si- and C-doped BNNTs can be viewed as an effective green catalyst for the reduction of N2O.

Influence of Defects in Boron Nitride Nanotubes in the Adsorption of Molecules. Insights from B3LYP-D2* Periodic Simulations

The adsorption of H2O, NH3 and HCOOH as polar molecules and C6H6 and CH4 as non-polar ones on a series of zig-zag (6,0) single-walled boron nitride nanotubes (BNNTs) both being defect-free (P_BNNT) and containing defects at the nanotube walls has been studied by means of B3LYP-D2* periodic calculations. We focused on defects derived from monovacancies of B (N-rich_BNNT) and N (B-rich_BNNT) atoms and also on Stone-Wales defects (SW_BNNT). The adsorption of polar molecules with defective BNNTs is generally based on dative interactions and H-bonding, and their adsorption energies strongly depend on the type of BNNT. N-rich_BNNT is the most reactive nanotube towards adsorption of polar molecules, as in all cases deprotonation of the polar molecules is spontaneously given upon adsorption. The strength in the adsorption energies is followed by B-rich_BNNT, SW_BNNT and P_BNNT. Adsorption of non-polar molecules is mainly dictated by dispersion interactions, and, accordingly, the adsorption energies are almost constant for a given molecule irrespective of the type of nanotube.

Effects of C1–3-doping on electronic and structural properties of Stone–Wales defective boron nitride nanotubes as well as their NO gas sensitivity

In this work, a first principle exploration was performed to investigate the electronic and structural properties of C-doped Stone–Wales (SW) defective (6,0) single-walled boron nitride nanotubes (BNNTs) as well as their chemical sensitivity toward NO gas using DFT approach.

Defect induced plasticity and failure mechanism of boron nitride nanotubes under tension

The effects of Stone-Wales (SW) and vacancy defects on the failure behavior of boron nitride nanotubes (BNNTs) under tension are investigated using molecular dynamics simulations. The Tersoff-Brenner potential is used to model the atomic interaction and the temperature is maintained close to 300 K. The effect of a SW defect is studied by determining the failure strength and failure mechanism of nanotubes with different radii. In the case of a vacancy defect, the effect of an N-vacancy and a B-vacancy is studied separately. Nanotubes with different chiralities but similar diameter is considered first to evaluate the chirality dependence. The variation of failure strength with the radius is then studied by considering nanotubes of different diameters but same chirality. It is observed that the armchair BNNTs are extremely sensitive to defects, whereas the zigzag configurations are the least sensitive. In the case of pristine BNNTs, both armchair and zigzag nanotubes undergo brittle failure, whereas in the case of defective BNNTs, only the zigzag ones undergo brittle failure. An interesting defect induced plastic behavior is observed in defective armchair BNNTs. For this nanotube, the presence of a defect triggers mechanical relaxation by bond breaking along the closest zigzag helical path, with the defect as the nucleus. This mechanism results in a plastic failure.

Carbon monoxide adsorption on carbon atom doped perfect and Stone–Wales defect single-walled boron nitride nanotubes: a DFT investigation

The CO adsorption on the perfect and defective boron nitride nanotubes (BNNTs) was investigated using the density functional theory at the B3LYP/LanL2DZ theoretical level. The 7-layered armchair (5,5) BNNT doping with C atom on B and N sites was selected for the doped BNNT models, in which the ends of the BNNTs were saturated by hydrogen atoms. The structural and electronic properties of BNNTs and their adsorption configurations with CO were obtained. The binding energies of carbon atom doping on BNNT and adsorption energies of CO molecules on BNNTs were also calculated. The adsorption strength of the CO on BNNT was significantly improved by defective and doped structural creation. The CO adsorption on carbon atom doping on the nitrogen site of Stone–Wales defect BNNT displayed the strongest adsorption with a binding energy of −2.46 kJ/mol.

Efficient Gate-tunable light-emitting device made of defective boron nitride nanotubes: from ultraviolet to the visible

Boron nitride is a promising material for nanotechnology applications due to its two-dimensional graphene-like, insulating, and highly-resistant structure. Recently it has received a lot of attention as a substrate to grow and isolate graphene as well as for its intrinsic UV lasing response. Similar to carbon, one-dimensional boron nitride nanotubes (BNNTs) have been theoretically predicted and later synthesised. Here we use first principles simulations to unambiguously demonstrate that i) BN nanotubes inherit the highly efficient UV luminescence of hexagonal BN; ii) the application of an external perpendicular field closes the electronic gap keeping the UV lasing with lower yield; iii) defects in BNNTS are responsible for tunable light emission from the UV to the visible controlled by a transverse electric field (TEF). Our present findings pave the road towards optoelectronic applications of BN-nanotube-based devices that are simple to implement because they do not require any special doping or complex growth.

Carbon Doping of Defect Sites in Stone–Wales Defective Boron-nitride Nanotubes: A Density Functional Theory Study

We have performed a density functional theory study to investigate the effect of carbon doping on Stone–Wales (SW) defective sites in the armchair (4, 4), (5, 5) and (6, 6) BNNTs, in order to remove structural instability induced by homonuclear N–N and B–B bonds. Two different orientations of SW defect are considered, parallel and diagonal, and then C atoms are doped at different positions of the defect sites. In general, it seems that among the considered arrangements, C atoms prefer to be substituted for the homonuclear B–B bond. The larger HOMO–LUMO band gaps for the most stable configurations indicate that C doping at B–B sites is kinetically more favorable than the other ones. According to calculated nuclear quadrupole resonance (NQR) parameters as a result of C-doping on SW defective sites, the quadrupole coupling constants (CQ) of boron nuclei at defective sites decrease by about 0.508–1.406 MHz while 14N CQ of the defective sites, except for N8, increases. Interestingly, CQ of the N sites directly connected to dopant sites has maximum increment (0.612–2.596 MHz) while CQ of the N sites belonging to the B2N3 pentagon is undergone to some minor changes.

Thermo Neutral SN2 Reaction within Pristine and Stone–Wales Defective BNNTs and CNTs

The density functional theory (DFT) calculations have been performed to understand the effect of confinement on the Cl– exchange bimolecular nucleophilic substitution (SN2) reaction inside pristine and Stone–Wales (SW) defective boron nitride nanotubes (BNNTs). Results have also been compared with that of the same reaction inside the carbon nanotubes (CNTs). The kinetics of thermo neutral SN2 reaction is significantly influenced by the inner phase (concave-face) of the tubes. This evidence clearly reinforces that inner phase can act as a nanoreactor in accordance with the previous reports. It is also possible to note that the polarizabilities of BNNTs (CNTs) and being associated inside dielectric medium (solid solvation) influence the energetics of the reaction. Furthermore, the enhancement in the central energy barrier of the (SN2) reaction arises due to the nuclophile stabilization in the nanotube confinement through the noncovalent interactions. Comparison of results obtained from tubes of various size...

Dynamical aspects of the unzipping of multiwalled boron nitride nanotubes

Boron nitride nanoribbons (BNNRs) exhibit very interesting magnetic properties, which could be very useful in the development of spintronic based devices. One possible route to obtain BNNRs is through the unzipping of boron nitride nanotubes (BNNTs), which have been already experimentally realized. In this work, different aspects of the unzipping process of BNNTs were investigated through fully atomistic molecular dynamics simulations using a classical reactive force field (ReaxFF). We investigated multiwalled BNNTs of different diameters and chiralities. Our results show that chirality plays a very important role in the unzipping process, as well as the interlayer coupling. These combined aspects significantly change the fracturing patterns and several other features of the unzipping processes in comparison to the ones observed for carbon nanotubes. Also, similar to carbon nanotubes, defective BNNTs can create regions of very high curvature which can act as a path to the unzipping process.

Fracture Patterns of Boron Nitride Nanotubes

ABSTRACTDuring the last years carbon-based nanostructures (such as, fullerenes, carbon nanotubes and graphene) have been object of intense investigations. The great interest in these nanostructures can be attributed to their remarkable electrical and mechanical properties. Their inorganic equivalent structures do exist and are based on boron nitride (BN) motifs. BN fullerenes, nanotubes and single layers have been already synthesized. Recently, the fracture patterns of single layer graphene and multi-walled carbon nanotubes under stress have been studied by theoretical and experimental methods. In this work we investigated the fracturing process of defective carbon and boron nitride nanotubes under similar stress conditions. We have carried out fully atomistic molecular reactive molecular dynamics simulations using the ReaxFF force field. The similarities and differences between carbon and boron nitride fracture patterns are addressed.