BN Sheet Research Articles

To Examine the Adsorption Behavior and Dissociation of Hydrogen Selenide (H2Se) Gas on Pristine and Transition‐Metal (Fe, Mn)‐Doped Boron Nitride Nanosheets: A DFT Study

AbstractIn this study, the adsorption and dissociation of H2Segas on pristine and transition metal (TM) atoms doped nanosheets have been investigated theoretically using density functional theory (DFT) calculations. To understand the adsorption mechanics, we have examined the adsorption energy, the charge transfer between the adsorbent and adsorbate, the band structure, the density of states (DoS), as well as the optical properties. The structural stability of TM atoms (Fe, Mn)‐ doped BN nanosheets have been verified by finding the cohesive energy. The adsorption energies of H2Se on pristine BN, Fe–BN, and Mn–BN sheets are −0.012, −7.627, and −10.001 eV, respectively; that is, the H2Se gas get dissociated when interacted with the Fe–BN and Mn–BN nanosheets. The relaxed geometrical structures of complexes and electron density difference (EDD) map analysis displayed that the H2Se gas makes bond with TM‐doped nanosheets, that is, dissociated. Furthermore, we viewed the optical properties of the pure, TM‐doped nanosheets as well as the gas‐adsorbed complex structure to demonstrate the adsorption behavior. Therefore, our obtained results demonstrated that the Fe‐ and Mn‐doped BN sheets are good candidates for adsorption and dissociation of H2Se gas.

Exploring the fascinating interplay of epigenetically modified DNA bases with two dimensional bare and P-doped Si2BN and BN sheets for biosensing applications: A compelling DFT perspective

Detecting epigenetically modified (EM) bases is crucial for disease detection, biosensing, and DNA sequencing. Two-dimensional P-doped Si2BN and BN sheets are used as sensing substrates in density functional theory (DFT) studies. Both the sheets are doped with a phosphorous atom at various atomic sites to examine the sheet's potential in detecting 5-hydroxymethylcytosine (5hmc), 5-methylcytosine (5mc), 7-methylguanine (7 mg) and 8-oxoguanine (8oxg) bases. Doping of the P atom in the Si2BN sheet improves the adsorption energy (Ead) of Ab+5hmc (−107.16 kcal/mol) and Ab+5mc (−78.36 kcal/mol), As+7 mg (−84.31 kcal/mol) in the gas and aqueous phase Ab+5hmc (−93.28 kcal/mol), An+7 mg (−78.92 kcal/mol) and As+5mc (−77.52 kcal/mol) respectively. Standard deviation (θ) indicates that As complexes have high θ values ranging from 4.55 to 37.77, suggesting a high likelihood of distinguishing the bases. The P-doped BN complexes exhibit noticeable work functional shifting (Δϕ%) recommended that they can be used as ϕ-based sensors. Time-dependent DFT results suggest that when EM bases interact with P-doped Si2BN complexes, significant blue shifts (hypsochromic) and red shifts (bathochromic) are observed in the visible and near-infrared spectrum. Hence, the above finding suggests that P-doped Si2BN sheets are highly effective for sensing EM bases and are recommended for DNA/RNA sequencing applications.

Combustion synthesis of tunable‐aspect‐ratio β‐Si3N4/BN composite ceramic materials

AbstractHigh thermally conductive β‐Si3N4 is a new type of filler for thermally conductive materials. Tailoring its aspect ratio is crucial to optimize the preparation process and performance of polymer‐based thermal conductive materials. In this work, β‐Si3N4/BN thermally conductive hybrid fillers were prepared by combustion synthesis in a nitrogen atmosphere using low‐cost Si, B2O3 powders as raw materials, and the aspect ratio of β‐Si3N4 crystals were regulated according to the inhibiting growth strategy of second phase BN generated by in situ reaction. With the increase of B2O3, the content of BN increased slightly, while that of β‐Si3N4 decreased slightly. The aspect ratio of β‐Si3N4 decreased from 6.3 ± 1.9 to 1.9 ± 0.6, which might be ascribed to the inhibiting effect of BN sheets on the axial growth of rod‐like β‐Si3N4. Low‐aspect‐ratio β‐Si3N4/BN/epoxy composite exhibited high thermal conductivity of 1.04 W·m‐1·K‐1at the solid content of 50 wt%, which was 372.7% and 30.0% higher than that of neat epoxy and 40 wt% high‐aspect‐ratio β‐Si3N4/epoxy composite, respectively. In addition, β‐Si3N4/BN/epoxy composite also had good mechanical properties.

Facile preparation of thermally conductive fiber film by self‐assembling interconnected boron nitride nanosheets for effective thermal interface materials

AbstractBoron nitride (BN) has garnered significant attention for its potential in developing thermally conductive materials owing to its inherent insulating properties and high thermal conductivity. However, achieving high thermal conductivity in bulk materials or 3D structures constructed by BN sheets has remained challenging. In this study, we present a novel approach to design a high‐quality BN fiber using xanthan gum (XG) as a skeleton, aiming to facilitate heat dissipation in integrated circuits. The resulting thermally conductive film, with orderly and compactly arranged BN sheets in the XG skeleton, exhibits a remarkable in‐plane thermal conductivity of 8.26 Wm−1 K−1 and an out‐of‐plane thermal conductivity of 1.35 Wm−1 K−1. This film efficiently enables fast heat dissipation for LED chips and thermoelectric generators. Finite element simulation further supports the efficient heat transfer capacity of the BN fiber films.Highlights A high‐quality BN fiber was prepared by a facile approach. The BN fiber film exhibited high thermal conductivity. This film enables fast heat dissipation in practical applications.

Tandem indium oxide-boron nitride catalysts for oxidative dehydrogenation of propane.

This study introduces a novel approach of precisely depositing In2O3 nanoislands on the edges of BN sheets using selective atomic layer deposition. The modified catalysts demonstrated a significant improvement and characterization results revealed that the presence of In2O3 nanoislands, when free of BOx overlayers, is crucial in mitigating side reactions.

Complexes of the noble-gas atoms with borazine: Theoretical insights into structure, stability, and bonding character

The complexes of He, Ne, Ar, Kr and Xe with B3N3H6 were investigated by MP2, CCSD(T), and SAPT ab initio methods, and accurate procedures of bonding analysis. These systems are describable as mono-, di-, and tri-coordinated to the N atoms, their stabilities following the order N-mono < N-di < N-tri. The binding energies are within 1 or 2 kcal mol−1, and the interactions are dominated by the dispersion. The results are compared with those obtained recently from a DFT study on the complexes of He, Ne, Ar, and Kr with larger BN sheets [Phys. Chem. Chem. Phys. 24 (2022) 2554–2566.].

Multilayer C and BN δ‐Graphyne Sheets: An Exploration of Electronic and Optical Characteristics

AbstractThe structural, electronic, and optical characteristics of multilayer C δ‐graphyne and δ‐graphyne‐like BN sheets are discussed by first‐principles study. The calculations approved that the sheets are energetically favorable and thermally stable. The layers are held together by van der Waals forces. The mono‐ and tri‐layer C δ‐graphyne exhibit semimetallic behavior, while bi‐ and tetra‐layer C δ‐graphyne are semiconductors with negligible bandgap. All multilayer BN δ‐graphyne sheets are insulators with indirect bandgap. The bandgap increases with increasing number of layers. The optical behavior of the structures is anisotropic under electric fields polarized parallel and perpendicular to the sheets. The sheets exhibit high static dielectric constants, optical absorption, and optical conductivity. The electronic and optical characteristics of C and BN δ‐graphyne sheets promise their progress and application in the world of optoelectronics.

Boron Nitride/Ti3C2Tx MXene Nanosheet/WS2 Nanostructure Ternary Composites for All-Solid-State Flexible Asymmetric Supercapacitors

MXene-based nanomaterials are emerging candidates for energy storage applications due to their metallic conductivity, large surface area, and facile redox activity. The sheet restacking tendency and oxidation significantly reduce their application in different industries. This study reported a facile hydrothermal synthesis of a tungsten disulfide (WS2)-decorated Ti3C2Tx/functionalized-boron nitride (BN) nanohybrid as a cathode for all-solid-state flexible asymmetric supercapacitors. The MXene/functionalized BN heterostructure showed an increased surface area by reducing the sheet restacking. On the other hand, incorporation of WS2 over the MXene/functionalized BN sheets led to the addition of redox-active centers. The loading of WS2 over MXene/functionalized BN was varied to obtain an optimum electrode that delivered a specific capacitance of 1318 F g–1 at 1 A g–1 in 1 M KOH. An all-solid-state flexible asymmetric supercapacitor was assembled using PVA–KOH–KI gel electrolyte where KI functioned as a redox additive to increase the supercapacitor’s performance. The assembled device achieved an excellent specific capacitance of 140 F g–1 and a good energy density of 19.4 Wh kg–1 at 1 A g–1 with 84% capacitance retention after 10,000 cycles. Additionally, the assembled devices were able to brightly glow a light-emitting diode (LED), indicating their potential practical applicability in future portable electronics.

Failure of substrate-supported hexagonal boron nitride under complicated loading conditions

Buckling and fracture are two crucial failure modes of h-BN sheet and establishing the criterion for the failure modes is the prerequisite to guarantee the proper applications of h-BN sheet in practice. For the failure of h-BN sheet, previous studies mainly focused on the freestanding h-BN sheet under uniaxial or equi-biaxial loadings. However, for the more general case in practice, the critical failure of substrate-supported h-BN sheet under complicated loadings remains to be studied. In this paper, the substrate-supported h-BN sheet under complicated loadings is considered to reveal the failure mechanism and to establish the criteria for both the buckling and fracture. In order to predict the critical failure stresses efficiently and accurately for complicated loadings, a modified mode-independent energy-based analysis method (mMIEM) is proposed. Then, by analyzing the stress state and observing the failure features, the rational criteria for the buckling and fracture are established and the space of the allowable stress for the SiO2 substrate supported h- BN sheet is provided. The results indicate that the buckling of h-BN sheet is dominated by the second principal stress, namely the maximum compressive stress, while the fracture depends on the stresses along and vertical to the armchair direction rather than the principal stresses. Moreover, the substrate has a significant effect on the critical buckling of the h-BN sheet but has little effect on the critical fracture. The failure criterion and allowable stress space can be used in the design and evaluation of the h-BN based electronic devices.

Electrical tree evolution of two-dimensional BN sheet composite epoxy resin with different particle size

The packaging insulation of power electronic devices works in high-frequency, high-voltage, and high-temperature environments, which suffers from electrical tree aging and seriously restricts the reliable operation of power electronic devices. In this paper, WZ breakdown model is used and the tree growing and fractal dimension characteristics with different sheets size are simulated. In addition, electrical tree initiation and growing characteristics of BN/epoxy resin composites are observed and studied under high-frequency voltage. Results show that with the increasing sheet size, tree initiation voltage increases first and then decreases. From the simulation and experimental results, after adding two-dimensional sheet, electrical tree tends to be more bifurcated, and as the sheet size increases, the growing rate decreases, the fractal dimension of tree increase correspondingly. It is believed that by introducing BN sheet into the matrix, the barrier effects and the forming deep trap both make electrical tree difficult to initiate and grow. The above researches could provide a solution to the regulation of electrical tree aging performance in the insulation layer of power electronic devices.

Activation of h‐BN and SiC monolayer sheets through foreign atom substitution; a comparative study based on ab‐initio method

AbstractHere, we studied two different 2D monolayer systems (i.e., h‐BN and SiC), which exhibit unique electronic and magnetic properties. We analyzed the effects of Transition Methods (TM) doped atoms (i.e., Mn, Ni, and Sc) on the single vacancy (SV) h‐BN and SiC systems using first principles calculations. Through comparison we found that Mn substitution in SV h‐BN and SiC can modify their electronic and magnetic properties having larger magnetic moment as compared to other dopants (i.e., Ni and Sc.). Band structure and PDOS plots confirmed that TM doping in SV h‐BN can convert the pure h‐BN (insulator) to semiconductor, metal, or semi‐metal, it is also observed from the results that Mn‐doped h‐BN has higher band gap approximately equal to Eg ~ 2.7 eV during the negative spin and has smaller band gap, that is, (Eg ~ 1.1 eV) during the positive spin. Similarly doping with the TM atoms on the SV SiC monolayer system can convert pure SiC to metal or half metal. In addition, Mn‐doped SiC showed semimetal property having 0 eV band gap. These finding will help us to vary the electronic and magnetic properties of the pure h‐BN and SiC sheets which can be used for the opto‐electronic and spintronic applications.

Achieving High Thermal Conductivity in Epoxy Resin Composites by Synergistically Utilizing Al2O3 Framework and BN Sheet as Fillers

AbstractThe application of high thermal conductive Epoxy resin (EP) is an efficient way to improve the heat dissipation in electronic device. In this work, the thermal conductivity of EP is significantly improved by synergistically utilizing Al2O3 framework (AF) and boron nitride sheet (BN) as fillers. The polyurethane foams with different pore sizes are used to prepare AF for the first time. The microstructure characterization demonstrates the successful preparation of AF/EP and AF‐BN/EP with different AF pore size. The thermal conductivity of AF/EP is superior to that of Al2O3/EP composites with randomly distributed Al2O3 nanoparticles. The smaller pore of AF is beneficial to achieving a greater thermal conductivity in AF/EP composites. Especially, by combing BN with AF can further improve the thermal conductivity of AF‐BN/EP composites. The optimal value of 1.18 W m−1 K−1 (5.42 times high than pure EP) is obtained for 60 ppi‐AF‐20 wt% BN/EP composite. Besides, the dielectric property shows that by combining of AF and BN increases the permittivity, as well as low dielectric loss. The high thermal conductivity and excellent dielectric property are simultaneously achieved by synergistically utilizing AF and BN fillers, the resultant EP composites have great potential to be used in electronic devices.

Density functional theory study of the hydrogen evolution reaction in haeckelite boron nitride quantum dots

To satisfy arising energy needs and to handle the forthcoming worldwide climate transformation, the major research attention has been drawn to environmentally friendly, renewable and abundant energy resources. Hydrogen plays an ideal and significant role is such resources, due to its non-carbon based energy and production through clean energy. In this work, we have explored catalytic activity of a newly predicted haeckelite boron nitride quantum dot (haeck-BNQD), constructed from the infinite BN sheet, for its utilization in hydrogen production. Density functional theory calculations are employed to investigate geometry optimization, electronic and adsorption mechanism of haeck-BNQD using Gaussian16 package, employing the hybrid B3LYP and wB97XD functionals, along with 6–31G(d,p) basis set. A number of physical quantities such as HOMO/LUMO energies, density of states, hydrogen atom adsorption energies, Mulliken populations, Gibbs free energy, work functions, overpotentials, etc., have been computed and analysed in the context of the catalytic performance of haeck-BNQD for the hydrogen-evolution reaction (HER). Based on our calculations, we predict that the best catalytic performance will be obtained for H adsorption on top of the squares or the octagons of haeck-BNQD. We hope that our prediction of most active catalytic sites on haeck-BNQD for HER will be put to test in future experiments.

Screening of transition metal single-atom catalysts doped on γ-graphyne-like BN sheet for efficient nitrogen reduction reaction

Ammonia is an important industrial raw material. To promote the production of ammonia, it is urgent to develop efficient catalysts for nitrogen reduction reactions (NRR). Here, we have reported a novel electrocatalyst: γ -graphyne-like BN sheet-supported single metal atom (M/ γ BN, M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Ru) for NRR and studied the effect of Hubbard U correction in single-atom catalysts. The results of adsorption show that Ti/ γ BN, V/ γ BN, and Ru/ γ BN have the best adsorption energy for nitrogen. A detailed analysis of the NRR mechanism indicates that V/ γ BN has the lowest energy barrier in the rate-determining step when it follows a distal mechanism. Further analysis shows that the superior catalytic performance in V/ γ BN sheet is mainly attributed to the electron donation and back-donation mechanism. More interestingly, V/ γ BN greatly inhibited HER selectivity. By analyzing the doping structure and adsorption system, it can be found that when considering Hubbard U correction, there will be an obvious correlation between energy and distance. This study not only provides a basis for understanding the mechanism of nitrogen reduction reaction catalyzed by single-atom catalysts but also provides a new design idea for the rational design of high-efficiency NRR catalysts. • A novel BN based single-atom catalyst, Metal/γ-graphyne-like BN as an NRR electrocatalyst. • V/γBN follows the distal mechanism with low overpotential (0.190 V) and barrier (0.412 eV). • Excellent NRR catalytic activity comes from electron donation and back - donation mechanism.

Phenyl- and naphthyl-type heteroatom substitution blocks in naphthylene-[formula omitted]: A DFT study

Two-dimensional naphthylene-γ is a recently proposed carbon allotrope based on the concatenation of phenyl- and naphthyl-like blocks through tetragonal rings. This system is a narrow-gap semiconductor, which is also suitable to be cast into a boron-nitride configuration since it is a bipartite structure featuring only even-membered rings. It turns out BN configurations of naphthylene-γ can potentially result in systems suitable to be embedded into nanoelectronics applications, since they are expected to exhibit robust band gaps. With this motivation, we investigate the electronic properties of several hybrid systems hypothetically obtained by replacing part of naphthylene-γ’s C atoms by BN sectors with different concentrations. Our first principles simulations are based on density functional theory and show that the energy gap for these systems does not vary monotonically with increasing BN concentration. In fact, strategical choices for the sites undergoing C-to-BN substitution result in specific modifications in the electronic signature of the systems. We also investigated full-BN naphthylene-γ sheets which show band gaps significantly different from those of hexagonal-BN. We further investigated nanoribbons based on these BN sheets, showing that they closely follow the properties of their parent 2D structure, as they feature frontier states internally located over the ribbon structures.

Preparation and Properties of Epoxy Composites with Multi-Scale BN Sheets

Epoxy resin is one of the most widely used thermosetting polymers and commonly applied in power electronics field. The intrinsic properties of epoxy can be improved by the introduction of inorganic filler, thus fabricating a composite material. In this paper, different scales of modified boron nitride (BN, 1 μm, 10 μm) were used to improve the thermal conductivity of epoxy resin. The surfaces BN were modification by a silane coupling agent to improve the compatibility between BN and epoxy resin. The effects of micro-and nano-BN sheets on the microstructure, breakdown strength, thermal and mechanical properties of epoxy resin composite were studied. The characterization of its morphology by scanning electron microscopy shows that nano-BN distribution is in the middle of micro-BN, forming a better bridging effect. The data of the breakdown strength and thermal conductivity indicated that when the content of micro-BN is 30 wt% and nano-BN is 20 wt%, the thermal conductivity of BN/epoxy composite was 1.52 W/m·K. In addition, the breakdown strength is 77.1 kV/mm. Thus, this type of BN-filled BN/EP composites with remarkable insulation and thermal conductivity properties would have potential for power engineering materials.

High orientation structure in UHMWPE/BN composites continuously obtained by elongational flow field leading to superior thermal conductivity

AbstractUltra‐high‐molecular‐weight polyethylene/boron nitride (BN) composites have been continuously prepared successfully by eccentric rotor extruder (ERE) based on elongational flow. Optical microscopy (OM), scanning electron microscopy (SEM), x‐ray diffraction (XRD), thermal conductivity test, heat‐dissipation test, and tensile test were performed to investigate the orientation structure, thermal conductivity, mechanical properties, and insulation properties. The orientation factor and thermal conductivity of the composites prepared by ERE were 79.3 and 3.75 W·m−1·K−1, which were much higher than those of composites prepared with a torque mixer (14.7 and 2.73 W·m−1·K−1, respectively). OM and SEM showed that the BN sheets were in contact inside the composites and formed an efficient thermal conductivity network. Besides, the composites prepared by ERE had satisfactory mechanical and insulation properties (&gt;1013 Ω·cm). This study provides experimental and theoretical guidance for industrial preparation of polymer/layered‐filler functional composites.

Front Cover: Single Atoms Anchored in Hexagonal Boron Nitride for Propane Dehydrogenation from First Principles (ChemCatChem 9/2022)

The Cover Feature shows propane dehydrogenation on an Ru single atom anchored at the N vacancy on the hexagonal BN (h-BN) sheet. In their Research Article, C. Xiong et al. investigate the stability of Pt, Au, and Ru single atoms anchored at B and N vacancies on h-BN and their potential for propane dehydrogenation using first principles density function theory and molecular dynamics. They find that Pt single atom at the B vacancy in h-BN and Ru single atom at the N vacancy in h-BN are very stable and show excellent activity for propane dehydrogenation, as evidenced by low energy barriers for both dehydrogenation steps. Their work suggests that Pt and Ru single atoms anchored at vacancy sites in h-BN could be promising catalysts for propane dehydrogenation. More information can be found in the Research Article by C. Xiong et al.

Superior efficiency of BN/Ce2O3/TiO2 nanofibers for photocatalytic hydrogen generation reactions

One-dimensional BN/Ce2O3/TiO2 heteroarchitectures with high visible-light photocatalytic activity have been successfully obtained by an electrospinning technique. The properties of the prepared nanofibers were controlled using different ratios of cerium. The results of XPS characterization revealed that the Ce element is present in the valence state + III on the surface of the TiO2 nanofibers. Rietveld refinement of XRD data reveals that introducing small concentrations of Ce3+ (<3.0 at%) into the electrospinning solution leads to the formation of small amounts of rutile and brookite phases, a decrease in the crystallite size of the main anatase phase and a slight decrease in the c parameter and unit cell volume of the anatase phase. In contrast, only the anatase phase, which has a similar crystallite size and lattice parameters to that formed in the undoped sample, is observed when 3 at.% Ce is used. These results suggest that Ce3+ ions did not substitute Ti4+ ions in the lattice of both anatase and rutile phases, which can be explained by the large difference in the ionic radius of Ti4+ and Ce3+ ((r (Ti4+) = 60.5 pm, r (Ce3+) = 101.7 pm). Scanning electron microscopy demonstrates that the diameter of the obtained nanofibers decreases from 240 nm for pristine TiO2 to 101 nm, 70 nm, 40 nm for 2% Ce/TiO2 (CET2), BN/TiO2 (BT) and BN/2% Ce/TiO2 (BCET2), respectively. The d-spacing decreased by 0.3 nm after Ce incorporation as demonstrated by high-resolution transmission electron microscopy. XPS proved the presence of BN nanosheets along with Ce2O3 and TiO2 into the nanofibers. Compared with the pure TiO2 nanofibers (NF), the obtained Ce/Ti ratio of 2% (molar ratio) showed an enhancement of the visible-light photocatalytic activity to water splitting, which is 46 times higher than that of bare TiO2 NF. The Ce2O3 might improve the separation of photogenerated electrons and holes derived from the coupling effect of TiO2 and cerium oxide. This work also examines the modification of TiO2 (anatase) properties with hexagonal boron nitride (h-BN) and the impact this coupling has on photocatalytic activity. XPS proved the presence of BN nanosheets along with Ce2O3 and TiO2 into the nanofibers. The electron transfer rate was improved by BN exfoliation. The photocatalytic results indicated that the BN/Ce2O3/TiO2 nanofibers improve hydrogen production up to 5100 μmol/g for 6 h under visible light, which could be due to the presence of BN sheets that enhanced the separation of the photo-induced electron–hole pairs in TiO2 and increased the specific surface area compared to pure TiO2 and Ce2O3/TiO2 nanofibers. Moreover, the BN/Ce2O3/TiO2 could be easily recycled without decrease in the photocatalytic activity because of its one-dimensional nanostructure nature. Moreover, the present work focuses on the ternary composite of BN/Ce2O3/TiO2 for optimization of electronic and phonon transport properties using the state-of-the-art density functional theory (DFT). The calculated electronic density of states (DOS) modulus shows an excellent agreement compared with available theoretical and experimental data for hydrogen production.

Atomic-Level Structure of Mesoporous Hexagonal Boron Nitride Determined by High-Resolution Solid-State Multinuclear Magnetic Resonance Spectroscopy and Density Functional Theory Calculations

Mesoporous hexagonal boron nitride (p-BN) has received significant attention over the last decade as a promising candidate for water cleaning/pollutant removal and hydrogen storage applications. Here, high-resolution solid-state NMR spectroscopy and plane-wave density-functional theory (DFT) calculations are used to obtain an atomic-level description of p-BN. 1H–15N or 1H–14N heteronuclear (HETCOR) correlation experiments recorded with either conventional NMR at room temperature or dynamic nuclear polarization surface-enhanced spectroscopy (DNP-SENS) at ca. 100 K reveal NB2H, NBH2, NBH3+ species residing on the edges of BN sheets. Ultra-high field 35.2 T 11B NMR spectroscopy was used to resolve 11B NMR signals from BN3, BN2Ox(OH)1–x (x = 0–1), BNOx(OH)2–x (x = 0–2), BOx(OH)3–x (x = 0–3), and BOx(OH)4–x– (x = 0–4). Importantly, 2D 11B dipolar double-quantum–single-quantum homonuclear correlation spectra reveal that many pore/defect sites are composed of boron oxide/hydroxide clusters connected to the BN framework through BN2O units. 1D and 2D 11B{15N} HETCOR NMR experiments, in addition to plane-wave DFT calculations of nine different structural models, further confirm the assignment of all NMR signals. The detailed structure determination of the pore and edge/defect sites within p-BN should further enable the rational design and development of next-generation p-BN-based materials. In addition, the techniques outlined here should be applicable to determine structure within other porous and/or boron-based materials.