Boron Nitride Nanofibers Research Articles

High-surface area active boron nitride nanofiber rich in oxygen vacancies enhanced the interface stability of all-solid-state composite electrolytes

Solid electrolytes are the most promising candidate for replacing liquid electrolytes due to their safety and chemical stability advantages. However, a single inorganic or organic solid electrolyte cannot meet the requirements of commercial all-solid-state batteries (ASSBs), which motivates the composite polymer electrolyte (CPE). Herein, a CPE of boron nitride nanofiber (BNNF) with a high specific surface area, rich pore structure, and poly (ethylene oxide) (PEO) are reported. Anions strongly adsorb on the surface of BNNF through electrostatic interactions based on oxygen vacancies, promoting the dissociation of lithium salts at the two-phase interface. The three-dimensional (3D) BNNF network provides three advantages in the CPE, including (i) improving ionic conductivity through strong interaction between polymers and fillers, (ii) improving mechanical properties through weaving a robust skeleton, and (iii) improving stability through a rapid and uniform thermal dispersion pathway. Therefore, the CPE with BNNF delivers high ionic conduction of 4.21 × 10−4 S cm−1 at 60°C and excellent cycling stability (plating/stripping cycles for 2000 h with a low overpotential of ∼40 mV), which results in excellent electrochemical performance of LiFePO4 (LFP) full cell assembled with CPE-5BNNF-1300 (152.7 mAh g−1 after 200 cycles at 0.5 C, and 134.8 mAh g−1 at 2.0 C). Furthermore, when matched with high-voltage LiNi0.6Co0.2Mn0.2O2 (NCM622), it also exhibits an outstanding rate capacity of 120.4 mAh g−1 at 1.0 C. This work provides insight into the BNNF composite electrolyte and promotes its practical application for ASSBs.

Constructing multifunctional polyvinyl alcohol composite hydrogels with human-like skin properties using polyaniline-coated boron nitride nanofibers

Flexible conductive nanofibers play a crucial role in constructing hydrogels with human-like skin properties. However, it is still a challenge to construct flexible conductive nanofibers with good comprehensive properties. In this paper, we prepare composite fibers with excellent comprehensive properties by coating polyaniline (PANI) on the surface of flexible boron nitride nanofiber (BNNFs) template. BNNFs-PANI/PVA multifunctional composite hydrogels are created through the integration of BNNFs-PANI as nanofillers with soft poly (vinyl alcohol) (PVA) matrix using a one-pot self-assembly method. The composite hydrogels exhibit outstanding plasticity, self-adhesion, and self-healing properties, with a self-healing efficiency reaching up to 96% within 120 s. Furthermore, the tensile strength of the composite hydrogels has been enhanced by 36%, with the elongation at break exceeding 1500%. The compressive strength of the composite hydrogels at 60% strain is increased by 62%. Beyond these mechanical and self-healing features similar to human skin, the composite hydrogels also can serve as electronic pen for painting on a touchable electronic screen, simulating the function of human skin. Moreover, the dynamic changes in the abundant conductive network contribute to the composite hydrogels’ high strain sensitivity. Compared with pure PVA hydrogels, it is improved by 29%. Notably, the strain sensitivity of the composite hydrogels is higher than that of most reported hydrogel sensors. Therefore, the composite hydrogels also can be employed as a real-time human motion sensor, capable of detecting and distinguishing various human movements. We believe that employing BNNFs as templates for crafting highly flexible and conductive nanofibers will foster the advancement of flexible conductive nanomaterials with comprehensive properties. Furthermore, the outstanding properties of the prepared composite hydrogels contribute to the ongoing development of conductive hydrogels with skin-like functionalities.

Nanostructured silver-boron nitride hybrid materials: Toward high-performance antibacterial hydrogels with enhanced mechanical and thermal properties

Silver nanoparticles (AgNPs) are grown uniformly on the surface of white porous boron nitride nanofibers (BNNFs) via a thermal reduction method to overcome the issue of nanoparticle aggregation. The optical characteristics of the AgNPs are retained, with different colors present depending on reduction temperature. This mainly depends on the white appearance of BNNFs. In addition, compared to boron nitride (BN) nanosheets and nanospheres, abundant pore structure and high specific surface area of the BNNFs enable superior AgNPs loading without agglomeration. The prepared AgNPs-loaded BNNFs (Ag-BNNFs) are then incorporated into poly (vinyl alcohol) (PVA) hydrogels fabricated through cyclic freeze-thaw techniques to develop antibacterial Ag-BNNFs/PVA composite hydrogels. The addition of 3 wt% Ag-BNNFs increases the tensile strength by 73.1% and compressive strength by 92.8% relative to the unmodified PVA hydrogels. Thermal stability also improves considerably, with the maximum PVA decomposition rate shifting from 280.9°C to 323.6°C in the composite hydrogels. Importantly, a potent bactericidal effect against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are achieved, with 99.5% and 100% inhibition after 24 h exposure to the Ag-BNNFs/PVA composite hydrogels, respectively. This work demonstrates a new method of dispersing AgNPs with BNNFs, and the resulting Ag-BNNFs effectively enhance the mechanical properties, thermal stability and antibacterial activity of PVA hydrogels.

Cellulose nanofibers based composite membrane with high solar radiation and heat conduction for agricultural thermal dissipation application

Thermal dissipation materials that can emit thermal radiation and enhance thermal conductivity are critical for agricultural thermal management and the establishment of an energy efficient society. Here, cellulose nanofibers based composite membranes are prepared by extraction, homogenization, alkali treatment, and steam modification using rice straw as raw materials for agricultural thermal management. The composite membranes not only achieve a radiative cooling effect with high solar emissivity (0.89) for outdoor thermal management but also enables a synergetic effect with high thermal conductivity (2.103 W·m−1·K−1) to reduce the internal temperature of agricultural films, which is 7.2 °C cooler than mulch films. The alkali treatment process enables the formation of hydrogen bonds between boron nitride and cellulose nanofibers, thereby significantly enhancing the composite membrane's mechanical properties. The composite membranes exhibited excellent mechanical strength due to the new hydrogen bonds between boron nitride and cellulose nanofibers. Therefore, this work provides new ideas for exploring the comprehensive utilization of agricultural waste and the working mechanism for the preparation of agricultural waste-based materials, as well as a low-carbon development path of “agriculture-environment-energy”.

Boron Nitride Nanofibers as Catalysts for High-Efficiency Aerobic Oxidative Desulfurization

Boron Nitride Nanofibers as Catalysts for High-Efficiency Aerobic Oxidative Desulfurization

Atomically Dispersed Aluminum Sites in Hexagonal Boron Nitride Nanofibers for Boosting Adsorptive Desulfurization Performance.

The exploitation of highly efficient and cost-effective selective adsorbents for adsorptive desulfurization (ADS) remains a challenge. Fortunately, single-atom adsorbents (SAAs) characterized by maximized atom utilization and atomically dispersed adsorption sites have great potential to solve this problem as an emerging class of adsorption materials. Herein, aiming at improving the efficiency of ADS performance via the economical and feasible strategy, the desirable SAAs have been fabricated by uniformly anchoring aluminum (Al) atoms on hexagonal boron nitride nanofibers (BNNF) via an in situ pyrolysis method. Remarkably, Al-BN-1.0 exhibited a superior adsorption capacity of 46.1 mg S/g adsorbent for dibenzothiophene, with a 45% increase in adsorption capacity compared to the pristine BNNF. Additionally, it demonstrated excellent adsorption of other thiophene sulfides. Moreover, the ADS mechanisms have been investigated through special adsorption experiments combined with density functional theory (DFT) calculations. It was demonstrated that the superior ADS performance and selectivity of Al-BN-1.0 originate from the sulfur-aluminum (S-Al) and π-π interactions cooperating synergistically. This work would cast light on a novel fabrication strategy for the SAAs based on the two-dimensional material with a tunable metal site configurations and densities for varied selective adsorption and separation.

Boron nitride nanofibers enhanced composite PEO-based solid-state polymer electrolytes for lithium metal batteries

Polyethylene oxide (PEO)-based solid-state polymer electrolytes (SPEs) are limited by their poor cyclic stability and inferior ionic conductivity for applicating in high-safety, long-cycling and high-energy-density lithium metal batteries. Herein, porous boron nitride nanofibers (BNNFs) are filled into PEO-based SPE, which significantly suppresses Li dendrites growth and enhances the electrochemical performance of Li metal battery. BNNFs with high porosity have more active sites to connect with PEO, which can effectively reduce the crystallinity of the PEO matrix and enhance its ionic conductivity. Moreover, owing to the hardness and good stability of BNNFs, BNNFs/PEO/LiTFSI electrolyte exhibits a wider electrochemical window, better mechanical property and higher thermal stability compared with PEO/LiTFSI electrolyte. Consequently, the Li symmetric cell composed of 1% BNNFs/PEO/LiTFSI performs good cyclic stability (>1800 h), and the Li||1% BNNFs/PEO/LiTFSI||LFP full battery shows obviously improved performances in charge-discharge polarization voltage, discharge specific capacity, rate performance and cyclic stability than the Li||PEO/LiTFSI||LFP battery.

Boron nitride nanofiber/Zn-doped hydroxyapatite/polycaprolactone scaffolds for bone tissue engineering applications.

In this study, Zn doped hydroxyapatite (Zn HA)/boron nitride nanofiber (BNNF)/poly-ε-caprolactone (PCL) composite aligned fibrous scaffolds are produced with rotary jet spinning (RJS) for bone tissue engineering applications. It is hypothesized that addition of Zn HA and BNNF will contribute to cell viability as well as mechanical and osteogenic properties of the PCL scaffolds. Zn HA was synthesized by mixing Ca and P sources followed by sonication and aging whereas BNNF was obtained by the reaction of melamine with boric acid followed by freeze-drying for annealing of fibers. It is found that incorporation of both Zn HA and BNNF in PCL fibers resulted in higher calcium phosphate (CaP) precipitation on the scaffolds. Also, in vitro cell culture studies showed that presence of both Zn HA and BNNF also had synergistic effect for enhanced proliferation and osteogenic activity of Saos-2 cells. Mechanical properties of PCL-Zn HA-BNNF were found similar to that of non-load bearing bones. Furthermore, the presence of Zn HA and BNNF had synergistic effects to cell attachment, proliferation and spreading without causing cytotoxic effect on cells. The highest ALP activity was obtained in the PCL-Zn HA- BNNF group at days 7 and 14 due to release of zinc, calcium, phosphate and boron. Considering its mechanical and bioactivity properties, PCL-Zn HA-BNNF composite scaffolds hold promise as non-load bearing bone substitutes.

Porous boron nitride nanofibers enhanced sodium acrylate and acrylamide copolymer hydrogels for effective adsorption of Pb2.

A new composite hydrogel adsorbent for adsorption of Pb2+ has been prepared by combining porous boron nitride nanofibers (BNNFs) and the acrylamide and sodium acrylate copolymer (P(AANa-co-AM)) via a chemical crosslinking method. Porous BNNFs with abundant hydroxyl functional groups can form hydrogen bond interactions with carboxyl and amino functional groups of the copolymer in the composite hydrogel and carry and dissipate forces for the composite hydrogels. So the mechanical performances of the copolymer hydrogels can be effectively improved, which is very valuable for the practical application of the composite hydrogel to remove Pb2+ from waste water. The thermal stability and swelling performance of the pure copolymer hydrogels were also greatly improved. This is not only because of the strong hydrogen bond interactions but also the good thermal stability and flexibility of BNNFs. The composite hydrogel adsorbent shows superior adsorption capacity for Pb2+ (490.2 mg g-1) to most of the reported hydrogel adsorbents. The chemisorption dominates the whole adsorption process according to the pseudo-second-order kinetic and the Langmuir models. The composite hydrogel adsorbent also shows good reusability. Therefore, we believe that the prepared composite hydrogels will play an important role in removing Pb2+ from wastewater.

Effects of a porous boron nitride nanofiber on nano-mechanical properties in shallow surface of WC-Si3N4 composite

The nanoindentation technique has been applied to materials research for decades, such as WC, Si3N4, and other ceramics or composites. However, nano-mechanical properties in shallow surfaces were often unstable, especially for ceramics-based composites. In this paper, the mechanical properties of WC-10 wt.% Si3N4 without and with the addition of ultrafine porous boron nitride nanofiber were investigated by nanoindentation continuous stiffness measurement in this study. The effects of the porous fiber on elastic modulus and hardness were revealed, which led to more stable and regular profiles of the elastic modulus and hardness versus displacement curves. The curves were cut out and shown before the 30 nm displacement of the tip, which displayed the regularity of the profiles caused by the porous fiber more directly. The values were statistically analyzed at intervals of 10 nm after 30 nm displacement, and then lower standard deviations were observed. The different Si3N4 cracks made from Vickers indentation on the composites were photographed and associated with the regularity of the curves after the fiber addition. It’s considered that the regularity effects on mechanical properties of the porous boron nitride nanofiber on ceramics composites can be helpful in thin film studies, which are also in difficulties of mechanical properties scattering on the nanometer scale using continuous stiffness measurement.

Interdependent effects of surface and flexoelectricity on the electromechanical behavior of BNRC nanoplate

The present work deals with the static and dynamic behavior of boron-nitride (BN) reinforced piezoelectric nanocomposite subjected to mechanical load while considering flexoelectric and surface effects. Based on the modified Kirchhoff plate theory and Navier's solution, an analytical model is derived to investigate the electromechanical response of simply supported (SS) boron-nitride reinforced nanocomposite (BNRC) plates. In addition, a micromechanical model by employing the Mori-Tanaka (MT) approach is derived to investigate the effective elastic and piezoelectric properties of the BNRC lamina. The BNRC lamina is composed of BN nanofiber and polyimide matrix, such that the BN nanofibers are oriented along the 3-direction. Our outcomes reveal that the incorporation of the BN nanofiber shows a substantial enhancement in the effective longitudinal and transverse piezo-elastic coefficients of the BNRC lamina. Further, the outcomes of the analytical model by adopting the Kirchhoff plate theory illustrate that the effects of flexoelectricity and surface show significant enhancement in the stiffness of the composite at the nanoscale, although the surface effect is more pronounced when compared with the flexoelectric effect. Based on the present analysis, we observed that the effects of flexoelectricity and surface influence the static and vibrational properties of BNRC. Thus, at the nanoscale, these size-dependent properties cannot be neglected. This work presents an opportunity for the development of high-performance and efficient BNRC nanoplates.

Synergistic effect of hexagonal boron nitride and carbon nanofibers on tribological behavior of nanolubricant

The lubrication of the wind bearings is crucial for maintaining the efficiency and lifetime of the wind turbines. In this work, nanolubricant samples containing hexagonal boron nitride (h-BN), carbon nanofibers (CNFs), and carbon nanotubes (CNTs) were prepared and applied to friction pairs to study the tribological properties at different speeds and under different loads. The polyalphaolefin (PAO) sample with 6 wt% of CNF and 6 wt% of h-BN demonstrated the lowest and most stable average friction coefficient of GCr15/40Cr pair. Considering reduction of both wear loss and friction coefficient, the sample with only CNF is more suitable for low-load and low-speed working conditions. While the sample loaded with both h-BN and CNF is more suitable for high-load and high-speed working conditions.

Negatively charged insulated boron nitride nanofibers directing subsurface zinc deposition for dendrite-free zinc anodes

Negatively charged insulated boron nitride nanofibers directing subsurface zinc deposition for dendrite-free zinc anodes

Pd nanoparticles anchored on porous boron nitride nanofibers as highly active and stable electrocatalysts for formic acid oxidation

Direct formic acid fuel cells (DFAFCs) are promising power generation technologies for various electronic devices. The design of efficient and stable electrocatalysts for the formic acid oxidation reaction (FAOR) plays an important role for the commercial applications of the DFAFCs. Herein, porous boron nitride (BN) supported Pd nanoparticles (NPs) have been developed as unique and effective composite catalysts for FAOR. Porous BN nanofibers (BNNFs) has been utilized as a functional support to anchor of Pd NPs. The high specific surface area and rich porosity of BNNFs play a key role for the well-dispersion and stabilization of Pd NPs with uniform ultra-small size (~2.32 nm) on their surface. The developed Pd/BNNFs composite catalyst exhibits excellent catalytic activity for FAOR with the mass activity of 725 mA mg−1Pd and a very low onset potential (about −0.12 V). Comparative experiments confirm that the microstructure of porous BN carrier greatly affects the electrocatalytic behaviors of the composite catalyst in FAOR. As compared with the composite catalyst using BN microfibers (BNMFs) as a support, the developed Pd/BNNFs catalyst shows superior catalytic activity and long-term stability owing to the larger specific surface area of BNNFs and stronger interaction between Pd NPs and support. This study not only illustrates that porous BN is a desirable catalyst carrier for catalytic FAOR but also provides new ideas for the design of novel BN-based catalysts.

Amino-silane co-functionalized h-BN nanofibers with anti-corrosive function for epoxy coating

In this research, hexagonal boron nitride nanofibers co-functionalized with polydopamine and (3-aminopropyl) triethoxysilane (Fh-BNNFs) are used for developing anti-corrosion solvent-based nanocomposite epoxy coatings. The h-BNNFs are successfully synthesized byutilizing inexpensive precursors of melamine and boric acid. The prepared nanomaterials are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, thermal gravimetric analysis, field emission scanning electron microscopy, and N2 adsorption/desorption isotherms. The corrosion resistance of the pure and nanocomposite epoxy coatings is investigated by electrochemical impedance spectroscopy, Potentiodynamic polarization tests, salt spray, and pull-off adhesion measurements. The results indicate that the epoxy nanocomposite coatings containing optimum amount of the Fh-BNNFs show superior corrosion resistance. Moreover, density functional theory (DFT) method is applied to investigate the energetics and interaction mechanisms at each interface within the epoxy matrix.

Anchoring Copper Single Atoms on Porous Boron Nitride Nanofiber to Boost Selective Reduction of Nitroaromatics.

Single-atom catalysts have received widespread attention for their fascinating performance in terms of metal atom efficiency as well as their special catalysis mechanisms compared to conventional catalysts. Here, we prepared a high-performance catalyst of single-Cu-atom-decorated boron nitride nanofibers (BNNF-Cu) via a facile calcination method. The as-prepared catalyst shows high catalytic activity and good stability for converting different nitro compounds into their corresponding amines both with and without photoexcitation. By combined studies of synchrotron radiation analysis, high-resolution high-angle annular dark-field transmission electron microscopy studies, and DFT calculations, dispersion and coordination of Cu atoms as well as their catalytic mechanisms are explored. The BNNF-Cu catalyst is found to have a record high turnover frequency compared to previously reported non-precious-metal-based catalysts. While the performance of the BNNF-Cu catalyst is only of the middle range level among the state-of-the-art precious-metal-based catalysts, due to the much lower cost of the BNNF-Cu catalyst, its cost efficiency is the highest among these catalysts. This work provides a choice of support material that can promote the development of single-atom catalysts.

Enhanced adsorption of fluoroquinolone antibiotics on Cu-modified porous boron nitride nanofibers in aqueous solution

The microecology and human health threats caused by the abuse of antibiotics are increasingly serious, for which it is urgent to develop highly efficient adsorbents. In the current study, Cu modified porous boron nitride nanofibers (BNNF-Cu) with uniform distributions and stable structures were successfully synthesized. The surface area of BNNF-Cu can reach to 737.194 m2 g−1, which includes porous microstructure and rich surface groups. The removal performance of BNNF-Cu as an adsorbent for ofloxacin (OFL) in aqueous solution was systemically studied. Due to the addition of modifier copper, the adsorption capacities for fluoroquinolones pollutants including OFL, norfloxacin (NOR) and enrofloxacin (ENR) were greatly enhanced. The adsorption kinetic data and equilibrium adsorption isotherms are in line with the pseudo-second-order and the Freundlich models (R2 = 0.999), respectively, indicating that the adsorption of OFL onto BNNF-Cu was mainly multilayer chemisorption. Significantly, the adsorbent exhibits excellent removal percentage for OFL (99.74%) and the maximum adsorption capacity can reach to 305.32 mg g−1 at the pollutant concentration of 100 mg L−1. In addition, the influences of pH, temperatures and salinity on adsorption were also further researched. The outstanding removal efficiency can be maintained after several cycles, which proves excellent reusability. Finally, the BNNF-Cu adsorbent can offer a wide range of possibilities to eliminate antibiotics efficiently in industrial wastewater.

Porous boron nitride nanofibers as effective nanofillers for poly(vinyl alcohol) composite hydrogels with excellent self-healing performances.

New composite hydrogels with excellent self-healing properties were prepared by combining poly(vinyl alcohol) (PVA) and boron nitride nanofibers (BNNFs) via a facile one-pot assembly method. One-dimensional porous BNNFs with high aspect ratio, abundant hydroxyl functional groups, especially excellent flexibility which has been first demonstrated in experiments, can act as a decent inorganic nanofillers to effectively improve the mechanical and self-healing properties of PVA hydrogels. Both the tensile and compression performances of hydrogels have been greatly improved by the trace addition of BNNFs (only ∼1.25 wt%). Compared with other BN nanofillers with spherical particles and lamellar morphologies, BNNFs with high aspect ratios and good flexibility play a unique role in the preparation of PVA composite hydrogels with cross-linked three-dimensional polymeric networks. This can be explained by the different topological structures of composite hydrogels formed. The abundant hydroxyl functional groups can form a lot of reversible hydrogen bonds with the molecular chains of PVA, so the as-prepared hydrogels have a high self-healing efficiency. The best healing efficiency of the composite hydrogels with 2.25 wt% BNNFs reaches as high as 97.31% after self-healing for 30 minutes. The good flexibility of BNNFs is beneficial to the movement of the PVA chain, which is beneficial to the self-healing process of composite hydrogels. The outstanding self-healing performance is very important for the application of composite hydrogels in the biomedical field and wearable flexible devices.

Enhance the thermal conductivity and maintain insulation property of epoxy via constructing a three-dimensional network by doping hexagonal boron nitride and carbon nanofiber

Enhance the thermal conductivity and maintain insulation property of epoxy via constructing a three-dimensional network by doping hexagonal boron nitride and carbon nanofiber

Mechanical Properties of WC-Si3N4 Composites With Ultrafine Porous Boron Nitride Nanofiber Additive

WC-10 wt.% Si3N4 composites toughened with ultrafine porous boron nitride nanofiber (0, 0.01, 0.05, 0.1, and 0.15 wt.%) were prepared for the first time by spark plasma sintering. Compared with the WC-Si3N4 composite sintered in the same condition, the obtained WC-10 wt.% Si3N4 composites with ultrafine porous boron nitride were found to possess better hardness and fracture toughness. In addition, the Si3N4 phase in the UPBNNF toughened composites did not exhibit traditional catastrophic fracture as indicated in most investigations. In this study, the phenomena are discussed, and a probable mechanism is elucidated. It is deduced that the approach could be extended to materials with a feature of internal liquid phase during the sintering process and could improve hardness and fracture toughness.