Hexagonal Boron Nitride Nanoribbons Research Articles

Size dependence of melting process of armchair hexagonal boron nitride nanoribbon

The dependence on the initial configuration size of armchair hexagonal boron nitride nanoribbon (h-BNNR) is investigated by molecular dynamics simulation. The initial configuration size of armchair h-BNNR containing 10000, 20000, and 30000 identical atoms of B and N is heated from 50 K to 6000 K via Tersoff potentials to study the dependence on the initial configuration size of the phase transition from crystal to liquid of armchair h-BNNR. Some results can be listed: the phase transition exhibits a first-order type; the phase transition from crystal to liquid states depends on the initial configuration size; the melting points of 10000, 20000, and 30000 atoms are 3640 K, 4000 K, and 4400 K, respectively; the dependence on the heating rate of the armchair h-BNNR is considered for the case of 20000 atoms; in this study range, the melting point decreases as the heating rate decreases; the atomic mechanism of melting process is studied by analyzing the parameter and the appearance of the liquid-like atoms based on the critical value ; the critical value is used to classify solid-like and liquid-like atoms; the appearance of liquid-like atoms upon heating starts from the edges and grow inward; at the phase transition temperature, almost the entire crystal structure of the armchair h-BNNR configuration collapses.

Synthesis of novel Stachytarpheta jamaicensis flower liked hexagonal boron nitride nanoribbons (SJF-BNNBs) to efficiently improve the thermal/mechanical/electrical properties of flexible polyimide films

Heat dissipation has become a bottleneck restricting large-scale integration and flexible electronic technologies. This study reports a novel fabrication strategy to prepare flexible stachytarpheta jamaicensis flower-like hexagonal boron nitride nanoribbons (SJF-BNNBs) and their composite films with polyimide (PI). The effect of synthesis conditions on the morphology of SJF-BNNBs was investigated, and the growth mechanism was proposed. The in-plane and through plane thermal conductivities of the 4 wt% SJF-BNNBs/PI composite film reach 5.98 W m−1 K−1 and 0.79 W m−1 K−1, which are 3047 % and 316 % higher than those of the pure PI film, respectively. The in-plane and through plane thermal conduction enhancement efficiencies reach 761.8 % and 78.9 %, respectively. The tensile strength of the composite film is 61.7 % higher than that of pure PI, and maintains excellent electrical insulating and thermal stability properties. Infrared imaging tests verified the excellent heat dissipation performance of the composite film as a thermal interface material and a flexible copper clad laminate substrate, where the operating temperature of device could be reduced by 17.3 °C. To the best of our knowledge, SJF-BNNBs outperform the most efficient thermally conductive electrically insulating filler and are to break the overcome of polymer composites in heat dissipation applications.

Highly thermally conductive composites with boron nitride nanoribbon array

The traditional approaches to fabricate highly thermally conductive yet electrically insulating polymers relies mainly on adding massive ceramic fillers, which not only degrade the mechanical properties of polymers but also introduce more interfaces that lead to more scattering sites for phonons. Thus, it remains a major challenge to achieve high thermal conductivity with low filler content. Herein, to create directional conductors with fewer interfaces, we prepared array of vertically aligned hexagonal boron nitride nanoribbons (BNNRs) and then infused them with polydimethylsiloxane (PDMS). By optimizing the assembly density and crystalline structure of the BNNRs, the BNNR/PDMS composite achieves a remarkable through-plane thermal conductivity of 8.19 W/(m·K) at a low nanoribbon loading of 9.3 wt%, outperforming thermally conductive polymers with insulating fillers in spherical, fibrous, and flaky shapes at similar filler contents. Furthermore, high thermal–mechanical stability and outstanding electrical insulating properties are also discovered. In the thermal interface material (TIM) performance test, the BNNR/PDMS composite exhibits higher cooling efficiency than commercial TIMs, with a decrease in chip temperature of up to 16 °C, and maintains good thermal stability even after continuous heating–cooling processes of as long as 12 h.

Polarization effect induced by strain in hexagonal boron nitride nanoribbons

As a member of the hexagonal boron nitride (h-BN) system, boron nitride nanoribbons (BNNRs) have a BN polar covalent bonding infrastructure, and there are small-scale effects with strong correlation with piezoelectric effects as well as edge-strengthening quantum effects. However, realizing the polarization effect on BNNRs through experiments remains challenging. Here, we verify the strain-induced polarization effect on BNNRs through computational simulations and experiments. Using the ten-point iterative method, a computational model that can be used for the discrete difference of the polarization charge density and energy density of BNNRs is developed, and the correctness of the model for the polarization effect of Gaussian strain-induced BNNRs is verified by the computational programming in Python language. The polarization effects of strain-induced zigzag-edge BNNRs (ZBNNRs) for sawtooth strain, parabolic strain and oblique sawtooth strain are also investigated separately. In addition, the results of the computational simulations are experimentally verified to be consistent with the theoretical calculations. And the piezoelectric constant of − 276.88 pm∙V−1 for strained ZBNNRs is found to be four times higher than that of unstrained ZBNNRs. This study provides a relevant reference for the study of realizing the high integration of nano-scale h-BN based piezoelectricity for piezoelectricity.

Formation and stability of nanoscrolls composed of graphene and hexagonal boron nitride nanoribbons: insights from molecular dynamics simulations.

Nanoscrolls are tube-shaped structures formed when a sheet or ribbon of material is rolled into a cylinder, creating a hollow tube with a diameter on the nanoscale, similar to the papyrus. Carbon nanoscrolls have unique properties that make them useful in various applications, such as energy storage, catalysis, and drug delivery. In this study, we employed classical molecular dynamics simulations to investigate the formation and stability of nanoscrolls composed of graphene and hexagonal boron nitride (hBN) nanoribbons. Using a carbon nanotube (CNT) as a template to trigger their collapsing, we found that graphene/graphene, graphene/hBN, and hBN/hBN could form CNT-wrapped nanoscrolls at ultrafast speeds. We also confirmed that these nanoscrolls are thermally stable and discussed the other products formed from the interaction of these complexes and their temperature dependence. Gr/Gr and hBN/Gr nanoscrolls exhibit similar interlayer distances, while hBN/hBN nanoscrolls have wider interlayer distances than the other two composite nanoscrolls. These features suggest that hBN/hBN composite nanoscrolls could more efficiently capture small molecules because of their greater interlayer spacing. We conducted molecular dynamics simulations using the Forcite package in the Biovia Materials Studio software, which employs the Universal and Dreiding force fields. We considered an NVT ensemble with a fixed time step of 1.0 fs for a duration of 500 ps. The velocity Verlet algorithm was adopted to integrate the equations of motion of the entire system. We employed the Nosé-Hoover-Langevin thermostat to control the system temperature. The simulations were carried out without periodic boundary conditions, so there was no pressure coupling.

A DFT Based Approach for NO2 Sensing Using Vander Wall Hetero Monolayer

In the present study, two-dimensional (2-D) pristine and distorted hexagonal Zig-Zag Boron Nitride nano-ribbon (h-BNNR) has been used as a gas sensing material to detect Nitrogen dioxide (NO2). Distorted structures such as Al-doped, P-doped, and Stone–Wales defected structures are considered here as an electro-sensing material. The First principle density functional theory (DFT) computations-based ab initio approach has been used to investigate the electrochemical properties of pristine and distorted h-ZBNNR in presence of NO2. Upon NO2 adsorption, the conduction band/valance band and energy gap of the ribbon are decreased significantly. An increase in the transmission of electrons has been observed in increasing the bias voltage. Extensive simulations using Quantum wise have been done to validate the efficacy of the proposed gas sensor.

Fabrication of BN aerogels/Bi2Te3 composite thermoelectric generator (TEG) with high seebeck coefficient

Boron nitride (BN) aerogels materials have low density characteristics and stable three-dimensional network structure, which can be used as high thermal conductivity ultralight materials or thermal conductive polymer additives. The hexagonal boron nitride nanoribbons (BNNRs) aerogels material not only has a three-dimensional network structure with high specific surface area, but also has a two-dimensional band structure. It has ultra-low thermal conductivity along the in-plane direction, and has ultra-high aspect ratio and electrical insulation energy. However, the research on the thermoelectric properties of BN Aerogels and its composites is still blank. Therefore, it is of great significance to carry out the research on BN Aerogels, its thermoelectric composites, thermoelectric properties and the design of thermoelectric devices. In this paper, BN Aerogels were prepared by the combination of freeze-drying and high temperature thermal annealing, and the effects of 2-methyl-2-propanol (TBA) modification on the yield and quality of BN Aerogels were investigated. The experimental results show that TBA greatly reduces the width and thickness of BNNRs in BN Aerogels, and increases the aspect ratio of BNNRs. The composite thermoelectric particles were prepared by hot pressing to combine BN Aerogels and Bi2Te3 and the influence of the doping concentration of BN Aerogels on the thermoelectric parameters such as Seebeck coefficient and power factor of the thermoelectric battery was studied. The experimental results reveal that when the concentration of BN Aerogels is 1.48 wt%, the ZT value of BN Aerogels/p-Bi2Te3 composite thermoelectric particles is 0.719, while when the doping concentration of BN Aerogels is 1.96 wt%, the ZT value of BN Aerogels/n-Bi2Te3 composite thermoelectric particles is 0.577. And the TBA modified BN Aerogels/Bi2Te3 composite thermoelectric particles show that when the TBA doping concentration is 19.35 wt%, the ZT value of the TBA modified BN Aerogels/p-Bi2Te3 composite thermoelectric particles can reach 0.87, which is higher than that of BN aerogels/p-Bi2Te3 thermoelectric particles, and also much higher than that of the intrinsic p-Bi2Te3 thermoelectric particles. When the TBA doping concentration is 28.57 wt%, the ZT value of the BN Aerogels/n-Bi2Te3composite thermoelectric particles modified by TBA can reach 0.623, which is also higher than that of the BN aerogels/n-Bi2Te3 thermoelectric particles, and also much higher than that of the intrinsic n-Bi2Te3 thermoelectric particles. And based on the self-prepared TBA modified BN Aerogels/Bi2Te3 composite thermoelectric particles, the TEG thermoelectric battery was designed and manufactured. The Seebeck coefficient of the TEG thermoelectric battery can be reached 886.08 μV/K, the conductivity can be reached 9.74 × 104 S/m, and the thermoelectric power factor and power density are 7.65 × 104 μW/mK2 and 14.49 μW/cm3, respectively. This system reduces the need for physical space by using a common framework, which is conducive to the application of thermoelectric power generation technology in micro and small fields.

Thermal conductivity and interfacial thermal conductivity of complex boron nitride nanoribbons

Aiming at developing insulating materials with high thermal conductivity (TC), which can make up for the shortcoming that graphene cannot be used directly in electronic devices because of its zero band gap, we systematically study the thermal transport of the hexagonal boron nitride nanoribbons (BNNRs) composed of one multilayer central region (CR) and two monolayer regions (MRs). We show that the TC and the interfacial thermal conductivity (ITC) depend on the BNNR structure parameters and the temperature in different ways. As the CR layer number increases the ITC will decrease, indicating the two-layer BNNR will show the largest ITC. The TC will increase and the ITC will fluctuate around a certain value with increasing the MR length. However, with the increase of the BNNR width, both TC and ITC will show oscillations near certain values. Furthermore, we find that the ITC (TC) will increase (decrease) with the temperature increasing. Finally, we calculate the ITC of the compound BNNRs in different stacking manners and find the ITC for the AB stacking is greater than that for the AA stacking. This research presents the possible measures for manipulating heat transport and demonstrates that the whole heat transport performance is fundamentally determined by the interfaces.

Energy harvesting from mechanical vibrations: self-rectification effect.

The use of environmental vibrations as an energy source for stimulating small-scale energy harvesting (EH) devices has received significant attention in recent years. The conversion of alternating currents (AC) to direct currents (DC) is essential to powering electronic devices effectively. This study proposes a method where hexagonal boron nitride nanoribbons and nanotubes harvest energy and rectify the output voltage simultaneously with no need for an external rectifying circuit. This is a step to eliminate the necessity of batteries for EH devices, which require a constant power supply to generate electrical energy while maintaining their nanoscale dimensions. A molecular dynamics approach was used to simulate the response of boron nitride structures to mechanical vibrations. The polarization and voltage generated under tensile and compressing strain fields were calculated, and it was demonstrated that the buckling of the nano-mechanical structures could be engineered to rectify the generated voltage. This paves the way for the design of more efficient and scalable energy harvesting devices.

Hexagonal boron nitride nanoribbon as a novel metal-free catalyst for high-efficiency NO reduction to NH3

Electrochemical NO reduction is taken as a promising avenue to eliminate detrimental NO into valuable NH3 for a balanced nitrogen cycle. Current electrocatalysts for NO reduction are mainly focused on metal-bearing catalysts, while metal-free catalysts with low cost, excellent stability, activity and selectivity are strongly desired. Herein, we report hexagonal boron nitride nanoribbons (BNNRs) as novel metal-free catalysts for efficient NO adsorption and reduction into NH3. Our results reveal that bare edge B atoms of armchair and zigzag BNNRs act as active sites for spontaneous chemisorption and activation of NO, originating from significant electron transfer. Notably, in the subsequent NO reduction, NH3 can be spontaneously produced by armchair BNNR with a limiting potential (UL) of 0 V, which is superior to most well-established single-atom, biatom and pure traditional metal catalysts. The awesome catalytic activity for NO reduction is intrinsically introduced by the suitable NO adsorption strength on armchair BNNR, which is illuminated to appropriate electronic interactions between the active site and NO. Moreover, the catalytic selectivity of armchair BNNR for NH3 production at both low and high NO coverage can be well guaranteed due to the higher thermodynamic energy barriers in generating N2O, N2 and H2. Overall, our findings pioneer the catalytic application of BNNR and unveil the veil of metal-free catalysts for direct NO reduction to NH3.

Superelastic, Highly Conductive, Superhydrophobic, and Powerful Electromagnetic Shielding Hybrid Aerogels Built from Orthogonal Graphene and Boron Nitride Nanoribbons.

Three-dimensional (3D) elastic aerogels enable diverse applications but are usually restricted by their low thermal and electrical transfer efficiency. Here, we demonstrate a strategy for fabricating the highly thermally and electrically conductive aerogels using hybrid carbon/ceramic structural units made of hexagonal boron nitride nanoribbons (BNNRs) with in situ-grown orthogonally structured graphene (OSG). High-aspect-ratio BNNRs are first interconnected into a 3D elastic and thermally conductive skeleton, in which the horizontal graphene layers of OSG provide additional hyperchannels for electron and phonon conduction, and the vertical graphene sheets of OSG greatly improve surface roughness and charge polarization ability of the entire skeleton. The resulting OSG/BNNR hybrid aerogel exhibits very high thermal and electrical conductivity (up to 7.84 W m-1 K-1 and 340 S m-1, respectively) at a low density of 45.8 mg cm-3, which should prove to be vastly advantageous as compared to the reported carbonic and/or ceramic aerogels. Moreover, the hybrid aerogel possesses integrated properties of wide temperature-invariant superelasticity (from -196 to 600 °C), low-voltage-driven Joule heating (up to 42-134 °C at 1-4 V), strong hydrophobicity (contact angel of up to 156.1°), and powerful broadband electromagnetic interference (EMI) shielding effectiveness (reaching 70.9 dB at 2 mm thickness), all of which can maintain very well under repeated mechanical deformations and long-term immersion in strong acid or alkali solution. Using these extraordinary comprehensive properties, we prove the great potential of OSG/BNNR hybrid aerogel in wearable electronics for regulating body temperature, proofing water and pollution, removing ice, and protecting human health against EMI.

Polariton-induced transparency in hybrid 2D-material hetero-nanostructure with multi-functions

In this work, we theoretically investigate the polariton-induced transparency (PoIT) phenomenon based on a hetero-nanostructure that possesses hybrid two-dimensional (2D) materials. The hetero-nanostructure consists of periodic hexagonal boron nitride (hBN) and graphene nanoribbons that are separated by a dielectric spacer. Consequently, the near-field coupling between hyperbolic phonon-polaritonic resonances on hBN ribbons and localized surface plasmon resonances on graphene ribbons leads to a transparent window in the mid-infrared region, where strong phase dispersion as well as slow light effect exist. Such hybrid-polariton induced transparency is dominated by electric dipole, and possesses reciprocity. It can be passively tailored by changing structural parameters, and actively tuned by shifting graphene Fermi level. Meanwhile, it is insensitive to the incident angle within a wider range, and rotating polarization angle of the incident wave leads to the excitation of edge phonon polaritons, which enriches the adjustability of this heterostructure. Furthermore, it can serve as a mid-infrared sensor to detect surrounding refractive index change, gas concentration, and molecular fingerprints. And introducing a metal reflector can easily turn it to be a wide-angle dual-band light absorber. Finally, we investigate the near-omnidirectional PoIT and polarization-dependent PoIT in the extended bilayer metasurface. This work has potential mid-infrared multifunctional applications in low-dimensional hybrid-polaritonic nanodevices for phase manipulation, slow light, sensing, and absorption.

Strain induced coupling and quantum information processing with hexagonal boron nitride quantum emitters

We propose an electromechanical scheme where the electronic degrees of freedom of boron vacancy color centers hosted by a hexagonal boron nitride (hBN) nanoribbon are coupled for quantum information processing. The mutual coupling of color centers is provided via their coupling to the mechanical motion of the ribbon, which in turn stems from the local strain. The coupling strengths are computed by performing ab initio calculations. The density functional theory results for boron vacancy centers on boron nitride monolayers reveal a huge strain susceptibility. In our analysis, we take into account the effect of all flexural modes and show that despite the thermal noise introduced through the vibrations one can achieve steady-state entanglement between two and more number of qubits that survives even at room temperature. Moreover, the entanglement is robust against mis-positioning of the color centers. The effective coupling of color centers is engineered by positioning them in the proper positions. Hence, one is able to tailor stationary graph states. Furthermore, we study the quantum simulation of the Dicke–Ising model and show that the phonon non-equilibrium phase transition occurs even for a finite number of color centers. Given the steady-state nature of the proposed scheme and accessibility of the electronic states through optical fields, our work paves the way for the realization of steady-state quantum information processing with color centers in hBN membranes.

A DFT study on the electronic structure of in-plane heterojunctions of graphene and hexagonal boron nitride nanoribbons

The structural similarity between hexagonal boron nitride (h-BN) and graphene nanoribbons allows forming heterojunctions with small chain stress. The insulation nature of the former and the quasi-metallic property of the latter make them attractive for flat optoelectronics. Recently, shapes of graphene and h-BN domains were precisely controlled, creating sharp graphene/h-BN interfaces. Here, we investigated the electronic and structural properties of graphene (h-BN) nanoribbon domains of different sizes sandwiched between h-BN (graphene) nanoribbons forming in-plane heterojunctions. Different domain sizes for the non-passivated zigzag edge termination were studied. Results showed that the charge density is localized in the edge of the heterojunctions, regardless of the domain size. The systems with graphene domains are metallic, presenting null band gaps. The ones with the h-BN island are small-bandgap semiconductors with the highest bandgap value around 0.2 eV. The calculated bandgap has the same magnitude of the certain threshold for density functional theory. As a general trend, these materials exhibit a ferromagnetic behavior, which can be useful for magnetic applications at the nanoscale.

Carbon doped hexagonal boron nitride nanoribbon as efficient metal-free electrochemical nitrogen reduction catalyst

The electro-catalytic nitrogen reduction reaction (NRR) to produce ammonia is a significant and challenging mission in chemistry, in which metal-free NRR catalysts with high activity, stability and selectivity are still highly desired. Here, we have systematically investigated the properties of pristine and carbon doped hexagonal boron nitride nanoribbons (BNNRs) for efficient nitrogen capture and reduction. Our results suggest that BNNRs exhibit excellent N2 capture abilities, which are demonstrated to be originated from the edge lone pair electrons. Then we highlight that doping carbon can significantly enhance the NRR catalytic performance of BNNRs by reducing the NRR reaction overpotential from 1.14 to 0.39 V. Further analysis unravels that doping C can selectively modulate the adsorption free energy of NRR intermediates without influencing the excellent activation ability of pristine BNNRs, which has been confirmed to arise from the charge redistribution of edge boron atoms. Our findings pave the way of h-BN for N2 capture and pioneer the application of carbon doped BNNR as a novel NRR catalyst.

Effect of BNNR on mechanical properties of polyethylene nanocomposites

In the present study authors have studies the mechanical behavior of the hexagonal boron nitride nanoribbon (BNNR) filled polyethylene (PE) nanocomposites using classical mechanics based approach. Reaction force field in conjunction with L-J potentials are used to model the bonded and non-bonded interaction between PE and BNNR. In order to calculate the mechanical properties of the polyethylene based nanocomposites uniaxial tensile testing was applied on the PE/BNNR nanocomposites. Maximum stress, elastic modulus and strain at failure were calculated at the strain rate of 109 s−1 and compared with the corresponding pristine PE value. It was predicted that, 4% BNNR in polyethylene significantly enhance the maximum stress and elastic modulus. This study gives deep insight of the load transfer mechanism in case of the nanofiller reinforced polymer nanocomposites.

Plasmon-Acoustic Transducers Based on Graphene–2D Boron Nitride Structures for the Terahertz-Frequency Range

Graphene and 2D hexagonal boron nitride isomorphic to it are promising materials for application in nanoacoustics. Therefore, more detailed study on the possibilities of the development of plasmon-acoustic transducers for nanoacoustics with corresponding numerical estimations of their technical characteristics seems urgent. In this work, the possibility in principle of forming plasmon-acoustic transducers for nanoacoustic devices operating in the terahertz-frequency range is substantiated theoretically and via numerical calculations. A plasmon-acoustic transducer consisting of two subsystems, notably, piezoelectric and plasmon-polariton subsystems, is investigated as the analyzed model. The piezoelectric subsystem is made in the form of a hexagonal boron-nitride nanoribbon—an acoustic duct, the end part of which serves as a piezoelectric transducer exciting elastic waves of the terahertz range. The acoustic duct is overlapped with the plasmon-polariton subsystem in the form of a graphene nanoribbon, in which TM-polarized surface plasmon-polaritons propagate. The introduced electrical impedance of the piezoelectric subsystem and characteristic impedance of the plasmon-polariton subsystem are calculated. It is shown that their values can provide the optimal coordination of a load (the acoustic duct) with the plasmon-polariton waveguide. It is found that graphene nanoplasmonics and nanoacoustics based on piezoelectric planar boron nitride combine well with each other. This opens up broad opportunities for the development of a new class of nanoelectronic devices.

Collective near-field coupling and nonlocal phenomena in infrared-phononic metasurfaces for nano-light canalization

Polaritons – coupled excitations of photons and dipolar matter excitations – can propagate along anisotropic metasurfaces with either hyperbolic or elliptical dispersion. At the transition from hyperbolic to elliptical dispersion (corresponding to a topological transition), various intriguing phenomena are found, such as an enhancement of the photonic density of states, polariton canalization and hyperlensing. Here, we investigate theoretically and experimentally the topological transition, the polaritonic coupling and the strong nonlocal response in a uniaxial infrared-phononic metasurface, a grating of hexagonal boron nitride (hBN) nanoribbons. By hyperspectral infrared nanoimaging, we observe a synthetic transverse optical phonon resonance (strong collective near-field coupling of the nanoribbons) in the middle of the hBN Reststrahlen band, yielding a topological transition from hyperbolic to elliptical dispersion. We further visualize and characterize the spatial evolution of a deeply subwavelength canalization mode near the transition frequency, which is a collimated polariton that is the basis for hyperlensing and diffraction-less propagation.

Nonconventional screening of Coulomb interaction in hexagonal boron nitride nanoribbons

Strong excitonic effects is a very subtle issue in pristine hexagonal boron nitride (h-BN) and h-BN nanoribbons (h-BNNRs) due to large band gaps and reduced dimensionality. One of the reasons for such a large exciton binding energy (as large as 2.5 eV) is weak dielectric screening. Employing first-principles calculations in conjunction with the constrained random-phase approximation, we determine the strength of the Coulomb matrix elements for pristine h-BN and h-BNNRs with armchair and zigzag edges. Due to the nonconventional screening, the calculated off-site $U$ parameters for passivated h-BNNRs turn out to be rather sizable. Coulomb interaction is weakly screened at short distances and antiscreened at intermediate distances. Transition from screening to antiscreening takes place at a distance as low as 8 \AA{} in narrow passivated h-BNNR. The critical distance for the onset of antiscreening in hydrogen-terminated h-BNNRs is longer than in zero-dimensional molecules and clusters, but shorter than in graphene nanoribbons and carbon nanotubes. With increasing the width of the passivated h-BNNRs from the critical point about 12.6 \AA{}, the antiscreening effect is not observed. For completeness, on-site and long-range Coulomb interactions for metallic nonpassivated zigzag h-BNNRs are also reported.

Planar graphene/h-BN/graphene heterostructures for protein stretching and confinement.

Protein stretching and confinement in nanochannels is critical for advancing single-molecule detection techniques. For standard nanochannels integrated with nano-sensors, reducing their cross-section is beneficial for reading highly localized signals with minimal error, but results in increasing difficulty for the initial capture of any chain molecules due to the entropy barrier. Using molecular dynamics simulations, we show that spontaneous protein stretching can be realized by a two-dimensional (2D) heterostructure composed of a hexagonal boron nitride (h-BN) nanoribbon stitched with two graphene (GRA) sheets (i.e., a sandwiched GRA/BN/GRA structure). Due to fast protein diffusion on its flat surface and adsorption potential difference between two 2D materials, this planar nanochannel permits effective capture and elongation of three representative intrinsically disordered proteins including amyloid-β (1-42), polyglutamine (42) and α-synuclein (61-95). Moreover, we found that the extremely narrow h-BN stripe can provide stronger confinement for a longer polyglutamine chain after being stretched. Our approach has the potential to facilitate the bona fide readout of single-molecule protein sequencing techniques.