Boron Nitride Nanoribbons Research Articles

Porous boron nitride nanoribbons with large width as superior adsorbents for rapid removal of cadmium and copper ions from water

Porous boron nitride nanoribbons with large width and their possible mechanism for the removal of heavy metals.

Magnetic and electronic properties of zigzag boron nitride nanoribbons with nonmetallic atom asymmetric passivation

In this paper, we modify the magnetic and electronic properties of zigzag boron nitride nanoribbons (ZBNNRs) with asymmetric edge passivation nonmetallic (NM) atoms. The 12 possible cases of the XN-ZBNNR-BY systems (X, Y=O, S, F or P) can be divided into four types: the PN-ZBNNR-BY (Y=O, S or F), SN-ZBNNR-BY (Y=F, O or P), ON-ZBNNR-BY (Y=F, S or P) and FN-ZBNNR-BY (Y=O, P or S). The results show that all four types of the XN-ZBNNR-BY systems display the metallic properties in both channels mainly due to termination atoms O, S and P with 4, 4 and 3 p electrons, but only the ON-ZBNNR-BY (Y=F, S or P) systems display the magnetic properties. Furthermore, the total magnetic moments of the ON-ZBNNR-BY (Y=F, S or P) systems are contributed constantly by the termination O atoms and edge N atoms, regardless of termination Y atoms. Finally, the contributions to the total magnetic moments are very small for the inner N and B atoms.

Resonant Tunneling Diode by Means of Compound Armchair Boron/Nitride and Graphene Nanoribbons

The band gap of armchair graphene nanoribbons (AGNRs) can be modulated by replacing the carbon atoms with boron/nitride (BN) atoms to produce the compound nanoribbons, while the width of ribbons remains constant. By introducing BN doping atoms in the proper positions along the ribbon length, a double-barrier quantum-well structure is constructed. Consequently, negative differential resistance properties can be obtained by a combination of armchair BN nanoribbons (ABNNRs) and AGNRs as the compound ABNxGyNRs, in which x and y denote the number of BN and C atoms in the ribbon width, respectively. The proposed resonant tunneling diode (RTD), called an armchair BN graphene nanoribbon resonant tunneling diode (ABNGNR-RTD), is investigated in three different platforms including W, S, and H shapes. The numerical tight-binding model along with non-equilibrium Green’s function formalism is taken into account to study the electronic properties of the proposed RTD. The performance of the ABNGNR-RTD is examined in terms of device characteristics such as peak-to-valley ratio (PVR) and power dissipation. Based on the presented results, the performance of H-shaped devices is better than those of the other two cases in terms of PVR and power dissipation. In addition, the electronic properties of ABNGNR-RTDs can be modified by varying the relative width of ABNNRs with respect to AGNRs.

Metal-Free Boron Nitride Nanoribbon Catalysts for Electrochemical CO2 Reduction: Combining High Activity and Selectivity.

Developing metal-free catalysts for reduction of CO2 into energy-rich products is a popular yet very challenging topic. Using density functional theory calculations, we investigated the electrocatalytic performance of C-doped and line-defect (Ld)-embedded boron nitride nanoribbons (BNNRs) for CO2 reduction reaction (CRR). Because of the presence of bare edge B atoms neighboring to C dopant and C2 dimer as active sites, defective BNNRs exhibit high CRR catalytic activity and selectivity. The Ld-embedded BNNR structures with C2 dimer can not only convert CO2 into CO with very low overpotential of -0.5 V versus reversible hydrogen electrode but also ensure high selectivity in deactivating the hydrogenation channel of the desorbed CO to CH4. The C-doped zigzag and armchair BNNRs bind strongly to the CO intermediate and thus promote the selective conversion of CO2 to CH4, with the lower energy cost on the armchair ribbon than the zigzag one. The presence of edge B atoms and C dopant as dual active sites in BNNRs enables effective couplings between *CH2 and CO intermediates, leading to the formation of C2 products including C2H4 and C2H5OH, with a high selectivity for C2H5OH. Importantly, unwanted hydrogen evolution reaction is suppressed during CRR catalyzed by these BNNR-based configurations. Overall, the present findings highlight a promising new class of low-cost, metal-free electrocatalysts combining high CRR activity and selectivity.

Adsorption of CO gas molecules on zigzag BN/AlN nanoribbons for nano sensor applications

First-principle calculations have been performed to study the sensing of CO gas in various considered configurations. The adsorption of CO on zigzag BN nanoribbon (ZBNNR) and zigzag AlN nanoribbon (ZAlNNR) was modelled in five different possibilities. The effect of CO adsorption is to reduce the band gap in both types (BN/AlN) of the nanoribbons. Interestingly, a finite magnetic moment (0.96 μB for ZBNNR and 0.69 μB for ZAlNNR) has been obtained which depends upon the adsorption configuration of CO. Half-metallicity was also observed upon selective CO adsorption on ZAlNNR irrespective of the ribbon width. Present findings suggest that CO gas molecules could be detected through adsorption on BN/AlN nanoribbons via changes in electronic and/or magnetic properties.

Rectification in zigzag graphene/BN nanoribbon heterojunction

We investigate the effect of changed BN nanoribbon on the rectifying behavior in zigzag graphene/BN nanoribbon heterojunction using first principles based on non-equilibrium Green’s function and density functional theory. The increased BN length in the scattering region reduces the rectifying performance of the device, and the maximum rectifying ratio is [Formula: see text] in the heterojunction. We discuss the different rectifying characteristics for the designed models by calculating the transmission spectra at different biases. The rectifying phenomenon is further investigated by the projected density of state of device. Furthermore, we explain the observed negative differential resistance effect by the transmission spectra and transmission eigenstates. The results suggest that the zigzag graphene/BN nanoribbon heterojunction leads to the asymmetric current, causing the rectifying phenomenon, and the BN length in the scattering region can modulate the rectifying performance of zigzag graphene/BN nanoribbon heterojunction.

Electronic properties of edge-terminated zigzag hexagonal boron nitride nanoribbons

The electronic properties of edge-terminated zigzag hexagonal boron nitride nanoribbons (ZBNNRs) are studied with a tight-binding model which utilizes extended Hückel theory. The nanoribbons are terminated with F, Cl, O, S and P atoms, respectively. In all cases, the energy band structure and density of states are studied. Band properties and band gaps for each system are also reported. It is found that F and Cl atoms produce semiconducting properties when used as terminating atoms to the ZBNNRs and O, S and P atoms produce metallic properties when used as terminating atoms. The addition of the terminating atoms changes localized edge states and creates new ones, the effects of which can be seen across all available bonding orbitals.

Spin current generation by thermal gradient in graphene/h-BN/graphene lateral heterojunctions

Electron transport driven by a temperature gradient in a transport junction constructed by connecting a zigzag hexagonal boron nitride (h-BN) nanoribbon between two graphene nanoribbons (Gr/BN/Gr) is studied by density functional calculations and non-equilibrium Green’s function method. When the zigzag-edged graphene nanoribbons are in the ferromagnetic configuration, the BN barrier introduces a spin-dependent scattering and causes an ‘X’-type spin-dependent transmission functions around the Fermi level at equilibrium. In a linear response approximation, this gives rise to a Seebeck thermopower with opposite signs for different spins. It drives electrons with different spins to flow in opposite directions under a finite temperature gradient. Calculations show that the charge current is zero while spin current is not, thus pure spin current is generated. These findings suggests the great importance of BN barrier in the generation of thermal spin current using graphene and the idea should be taken into consideration in the design of spintronic devices using two dimensional materials.

Melting process of zigzag boron nitride nanoribbon

Zigzag hexagonal boron nitride nanoribbon (h-BNNR) model in two-dimensional (2D) case is studied via molecular dynamics simulation. The model contains 10000 atoms interacted via the Tersoff bond order potential. Temperature is increased from 50 K to 7000 K in order to see the evolution of various thermodynamic quantities, structural characteristics, and the occurrence of liquid-like atoms upon heating to a molten state. Lindemann criterion for 2D case is calculated and used to observe the appearance of liquid-like atoms. Atomic mechanism is analyzed on the basis of the occurrence/growth of liquid-like atoms, the formation of clusters, coordination number, and ring statistics. The largest cluster does not contain all liquid-like atoms in the whole range of temperature in this study. After reaching a peak at the melting point of this model, the largest cluster slightly decreases indicating that the single largest cluster of liquid-like atoms tends to form a ring-like 2D liquid zigzag h-BNNR. Armchair h-BNNR is studied to compare with zigzag h-BNNR model. The melting point of armchair h-BNNR (3600 K) is close to the experimental results of hexagonal boron nitride (h-BN) (from 2800 K to 3600 K) whereas the one of zigzag h-BNNR (4522 K) is higher than that of armchair h-BNNR and plane h-BN.

Spin-Polarized Transport Behavior Induced by Asymmetric Edge Hydrogenation in Hybridized Zigzag Boron Nitride and Graphene Nanoribbons

We fused zigzag graphene to boron nitride nanoribbons by gradually doping C atoms at only one edge of the ribbons to design a hybridized ZBxNyCz (x + y + z = 12) structure. To create asymmetric edge hydrogenation, the ZBxNyCz ribbons were monohydrogenated (N–H) at one edge and dihydrogenated (C–H2) at the opposite edge, and the structure was subsequently labeled as H-ZBxNyCz-H2. On the basis of density functional theory and non-equilibrium Green’s function, our simulation revealed that H-ZBxNyCz-H2-based devices present a variety of abnormal spin-polarized transport properties. When the value of x and y in the H-ZBxNyCz-H2 structure is not equal (i.e., z is an odd number), the spin-polarized currents are restricted, regardless of their ferromagnetic (FM) or anti-ferromagnetic (AFM) state. When x is equal to y (i.e., z is an even number), the H-ZBxNyCz-H2 structure exhibits negative differential resistance and spin-filtering features in the FM state. Conversely, in the AFM state, the spin-polarized currents of the structure exhibit an exceptional oscillation effect with spin polarization as high as 100% at certain bias voltages. By adjusting the width of graphene and the spin states, the resulting hybridized H-ZBxNyCz-H2 structure can be potentially applied to the fabrication of spin nanodevices with exotic functionalities.

Magnetic and electronic properties of zigzag boron nitride nanoribbons with nonmetallic atom terminations from first-principles

In this paper, we modify the magnetic and electronic properties of zigzag boron nitride nanoribbons (ZBNNRs) by adopting the method of edge-modification, which is achieved by passivating the edges of ZBNNRs with nonmetallic (NM) atoms H, O, S, F and P. Five different cases for XN + N-ZBNNR-B + BH, where X = H, O, S, F and P nonmetallic (NM) atoms are studied systematically. The calculated results indicate that for only X = P, the XN + N-ZBNNR-B + BH displays the half-metallic feature while the others exhibit metallic properties. The metallic feature of the XN + N-ZBNNR-B + BH (X = H, O, S, and F) systems is due to the contribution of both termination atoms and edge atoms to the total density of states at the Fermi level. The XN + N-ZBNNR-B + BH (X = H, O, S, F and P) are all magnetic materials. In addition, the half-metallic feature of the PN + N-ZBNNR-B + BH material is a new style of nano-material and a perfect candidate for spintronic applications.

Thermal conductivity, heat capacity and magnetic susceptibility of graphene and boron nitride nanoribbons

Using the Kubo-Greenwood formula based on Green's function method and modified third nearest neighbor tight-binding approximation based on density functional theory (DFT) calculations, the electronic properties and temperature dependence of thermal conductivity, heat capacity and pauli paramagnetic susceptibility of GNRs and BNNRs are calculated in presence of electric field. By increasing the electric field, the band gap of GNRs are approximately constant then decreases to zero, unlike to the band gap of BNNRs which decreases linearly to zero with increasing the electric field. The thermal conductivity, κ(T) for all structures increases with temperature to its maximum value and then decreases by further temperature increasing. In the lower (higher) temperature ranges, the electric field increases (decreases) the κ(T) for all structures. The thermal conductivity of A-BNNR is smaller (larger) than that of A-GNR in the lower (higher) temperature range. Both GNR and BNNR systems have schottky anomaly and their heat capacity increases before schottky anomaly peak and decreases after it. For Both GNR and BNNR systems, the paramagnetic susceptibility, χ(T) increases with temperature and the χ(T) of A-GNR is larger than χ(T) of A-BNNR.

Thermal properties of biased bilayer graphene and boron nitride nanoribbons

The electronic structure, temperature-dependent thermal conductivity κ(T) and heat capacity CV(T) of bilayer graphene nanoribbons (G/G), boron nitride nanoribbons (BN/BN) and graphene/boron nitride nanoribbons (G/BN) with AA and AB stacking are investigated using the tight binding model and Green’s function method. The results show that the bilayer G/G with AA stacking is metallic independent of the bias while other structures with AA and AB stacking are semiconductor in absence of bias and their band gap reduce in the presence of bias. The κ(T) for all structures increases with temperature to its maximum value and then decreases by further temperature increasing. The κ(T) of bilayer BN/BN is smaller than that of bilayer G/G and G/BN. The CV(T) of all structures increases up to a maximum value at T = TM (Schottky anomaly) and the corresponding TM value depends on the nanoribbons types and stacking as TM(G/G)<TM(G/BN)<TM(BN/BN). The Cv(T) of bilayer G/G is larger than G/BN and BN/BN.

Three-dimensional hexagonal boron nitride foam containing both [formula omitted] and [formula omitted] hybridized bonds

A family of semiconducting multiporous hexagonal boron nitride foams (HBNFs) with both sp2 and sp3 hybridized bonds is presented, which can be achieved by linking armchair BN nanoribbons (A-BNNRs). Based on density functional theory (DFT) calculations, we find that most of these HBNFs are dynamically, thermally and mechanically stable. Their electronic bandgaps vary in a wide range and exponentially change with the ribbon width. Interestingly, the electronic bandgaps of HBNFs can be classified into three groups. We also find that the edge effects affect not only the electronic band structure but also the length of B-N chemical bonds. In addition, the electron localization function of HBNFs are also been evaluated.

Parallel boron nitride nanoribbons and etch tracks formed through catalytic etching

One-dimensional (1D) catalytic etching was investigated in few-layer hexagonal boron nitride (hBN) films. Etching of hBN was shown to share a number of similarities with that of graphitic films. As in graphitic films, etch tracks in hBN commenced at film edges and occurred predominantly along certain crystal directions of its lattice, though it was shown that the tracks were generally narrower than those of few-layer graphene under similar processing conditions. It was also shown that catalytic hydrogenation can occur completely through a few-layer hBN film, demonstrating that this process can be used in the formation of isolated low-dimensional nanoscale structures from other layered 2D materials beyond graphene. This ability for thin hBN films to be etched completely through allowed for a crystalline substrate to guide the etching process, which was demonstrated with the successful etch track formation of few-layer hBN on single-crystalline sapphire substrates. The substrate-guided etching resulted in parallel few-layer hBN nanoribbons having an average width of 32 nm and spacing of 13 nm.

Enhancement of the surface reactivity of zigzag boron nitride nanoribbons by chlorine gas decoration: A computational study

In this study, we explored the field emission and chlorine sensing mechanisms of zigzag boron nitride nanoribbons (ZBNNRs). First principle calculations were used to investigate the surface reactivity of ZBNNRs within the framework of the density functional theory based on the local density approximation and generalized gradient approximation. Six different possibilities were considered for chlorine-gas termination and adsorption on ZBNNRs. The band gap of the ZBNNRs decreased monotonically as the ribbon width increased. The charges on the functional groups and corresponding bond lengths, i.e., B(N)-X and X-X (Cl-Cl), were dependent on the adsorption sites (B or N edge) and the types of functional groups, but independent of the ribbon width. Chlorine gas (Cl2) induced electrons into the conduction band and their consequent electronic states over the Fermi level enhanced the electrical conductivity. Transmission spectra demonstrated the spin-dependent electron tunneling from the valence band to the conduction band. Charge density analysis indicated the charge trapping behavior of the ZBNNRs. Cl2 introduced excess negative charges onto the active surfaces of the ZBNNRs to enhance their surface reactivity. Therefore, Cl2-decorated ZBNNRs can be employed as Cl2 sensors and they may also be useful in field emission applications.

Impact of interface types on spin transport in heterostructures of graphene/hexagonal boron-nitride nanoribbons

Abstract Using density functional theory in combination with non-equilibrium Green's functions, we investigate the spin transport in two heterostructures of graphene and hexagonal boron-nitride (h-BN) nanoribbons with C-B and C-N interfaces, respectively. Significant spin-filtering effect (over 80%) is observed in both C-B and C-N devices with bias ranging from 0 V to 0.3 V. Interestingly, the spin polarizations are opposite in these two devices, and prominent negative differential resistance (NDR) for both spin-up and spin-down currents is observed only in the C-N device. These findings provide insight into how the spin-transport properties of graphene/h-BN nanoribbons can be impacted by different types of interfaces of the heterostructures.

Zeeman-magnetic-field–induced magnetic phase transition in doped armchair boron-nitride nanoribbons

In this work, the magneto-charge structure factor (CSF) of hexagonal doped armchair boron-nitride nanoribbons (ABNNRs) has been addressed using the tight-binding Hamiltonian model and the Green's function technique. In particular, we study the charge static susceptibility in the presence of the Zeeman magnetic field. The calculations of the correlation function of charge densities lead to magnetic phase transitions, which are explained by the temperature-dependent magneto-CSF. We have observed different width-dependent CSF treatments in the presence and absence of magnetic field for both undoped and doped ABNNRs. Depending on the magnetic field strength, transitions from antiferromagnetic to the ferromagnetic (paramagnetic) arrangement of spins has been established for undoped (doped) ABNNRs. We have found that, furthermore, in addition to the magnetic field, the magnetic phase can be controlled by the concentration and incoming momentum of electronic dopants. These results have direct implications for the control of the dopant and magnetic field for the practical realization of boron-nitride nanoribbons-based spintronic applications.

Insulator-semimetallic transition in quasi-1D charged impurity-infected armchair boron-nitride nanoribbons

We address control of electronic phase transition in charged impurity-infected armchair-edged boron-nitride nanoribbons (ABNNRs) with the local variation of Fermi energy. In particular, the density of states of disordered ribbons produces the main features in the context of pretty simple tight-binding model and Green's functions approach. To this end, the Born approximation has been implemented to find the effect of π-band electron-impurity interactions. A modulation of the π-band depending on the impurity concentrations and scattering potentials leads to the phase transition from insulator to semimetallic. We present here a detailed physical meaning of this transition by studying the treatment of massive Dirac fermions. From our findings, it is found that the ribbon width plays a crucial role in determining the electronic phase of disordered ABNNRs. The obtained results in controllable gap engineering are useful for future experiments. Also, the observations in this study have also fueled interest in the electronic properties of other 2D materials.

Sensing properties of pristine boron nitride nanostructures towards alkaloids: A first principles dispersion corrected study

To understand the underlying physics behind the interaction of biomolecules with the nanomaterials to use them practically as bio-nanomaterials is very crucial. A first principles calculation under the frame work of density functional theory is executed to investigate the electronic structures and binding properties of alkaloids (Caffeine and Nicotine) over single walled boron nitride nanotube (BNNT) and boron nitride nanoribbon (BNNR) to determine their suitability towards filtration or sensing of these molecules. We have also used GGA-PBE scheme with the inclusion of Van der Waals (vdW) interaction based on DFT-D2. Increase in the accuracy by incorporating the dispersion correction in the calculation is observed for the long range Van der Waals interaction. Binding energy range of BNNT and BNNR with both alkaloids have been found to be −0.35 to −0.76 eV and −0.45 to −0.91 eV respectively which together with the binding distance shows physisorption binding of these molecules to the both nanostructures. The transfer of charge between the BN nanostructures and the adsorbed molecule has also been analysed by using Lowdin charge analysis. The sensitivity of both nanostructures BNNT and BNNR towards both alkaloids is observed through electronic structure calculations, density of states and quantum conductance. The binding of both alkaloids with BNNR is stronger. The analysis of the calculated properties suggests absence of covalent interaction between the considered species (BNNT/BNNR) and alkaloids. The study may be useful in designing the boron nitride nanostructure based sensing device for alkaloids.