Porous Boron Nitride Research Articles

Preparation of Poly(allylamine Hydrochloride) Grafted Porous Boron Nitride Fibers for Efficient Cr(VI) Adsorption from Aqueous Solution.

Cr(VI) pollution poses great harm to the cyclic utilization of groundwater and surface water resources. Efficient adsorbent materials have great potential to change this situation and assist in the restoration of ecosystems. This work chooses porous boron nitride fibers (pBN) with stable physical and chemical properties as the matrix, 3-aminopropyltriethoxysilane (APTES) as the coupling agent, and uses a one-step crosslinking method to graft poly(allylamine hydrochloride) (PAH) onto pBN, forming pBN-AS@PAH with fascinating Cr(VI) adsorption capacity. PAH is uniformly covered and modified on the surface of pBN, and the composite with high specific surface area (383.33 m2/g), large pore volume (0.37 cm3/g), and abundant amino groups. Its equilibrium adsorption capacity for Cr(VI) can reach up to 123.32 mg/g, and the adsorption behavior follows the quasi second-order kinetic model and Langmuir model, indicating the chemical adsorption process of monolayer. The adsorption style belongs to a spontaneous exothermic process and has the optimal adsorption effect at a pH of ~2. Additionally, after cycling for 5 times, the decrease rate of adsorption capacity is less than 10 %, showing an excellent reusability.

Adsorbent Properties of Porous Boron Nitride and Activated Carbon: A Comparative Study.

Porous boron nitrides possess beneficial properties such as high thermal and chemical stability which are critical for applications in adsorption processes. In order to assess possible fields of applications, trace-level adsorption isotherms of different hydrocarbons on two synthesized porous boron nitrides and two commercial activated carbons are compared. By normalizing the adsorptive loadings on the micropore surface area, superior adsorption performances of the BN materials on polar and aromatic adsorptives with up to 50% higher loadings compared to the activated carbons can be shown. Nonpolar adsorptives, on the other hand, feature higher specific loadings on the activated carbon. Consequently, the size of the micropore surface appears to be decisive for nonpolar adsorptives, while the higher polarity of the boron nitrides is the dominant influencing factor for the adsorption of polar and aromatic components. For an energetic study of the adsorbents, calorimetric experiments were performed to identify and discuss adsorbent-adsorptive interactions. While the initial heat of adsorption of the nonpolar n-hexane is lower on the boron nitride than on the activated carbon due to a less favorable spatial arrangement, toluene shows comparable values on both adsorbent classes and the polar acetone shows higher values on the polar boron nitride. Considering technical applications in adsorption technology, the thermal stability of the boron nitrides is investigated using spontaneous ignition temperatures and points of initial oxidation. Here, the porous boron nitrides with oxidation temperatures above 900 °C show about 400 °C higher values and thus a significantly higher thermal stability.

Enhanced Phosphate Adsorption by Cerium-Doped Porous Boron Nitride Nanosheets

Enhanced Phosphate Adsorption by Cerium-Doped Porous Boron Nitride Nanosheets

Controllable synthesis of porous boron nitride fibers modified by cobalt and nickel oxides for efficient ceftriaxone sodium adsorption from aqueous solution.

Antibiotics can easily enter the water environment through direct or indirect approach, causing environmental pollution and endangering the health of organisms. Therefore, development of highly efficient adsorbent materials to adsorb and remove antibiotics is necessary. Here, cobalt oxide and nickel oxide are uniformly and tightly bonded on the surface of porous boron nitride fibers (PBNFs-NiCo), significantly increasing the number of functional groups (B-O and N-H) and hydrogen bond receptors within PBNFs. The total pore volume and specific surface area of resulting PBNFs-NiCo can reach up to 0.48 cm3/g and 720.3 m2/g, respectively. Encouraged by the unique micromorphology and chemical composition mentioned above, PBNFs-NiCo exhibits excellent ceftriaxone sodium (CS) adsorption ability, showing the adsorption capacity and removal efficiency up to 410.9 mg/g and 96.5%, respectively. Chemical adsorption plays an important role in their adsorption behavior, abiding by Langmuir adsorption theory and pseudo-second-order kinetic equation. Importantly, PBNFs-NiCo exhibits fascinating adsorption effects in surroundings with pH ranging from 4 to 6, 25 °C and varying salt concentrations. This work would establish a practical and feasible foundation for the practical application of PBNFs-NiCo for CS adsorption in aqueous solution.

Hydrogen permselective membrane prepared by plasma treatment of porous ceramic substrates

Abstract Demand for hydrogen is increasing as we move toward a decarbonized society. Membrane separation methods have attracted attention as a way to reduce the cost of hydrogen production. In this study, we focused on boron nitride (BN) as a chemically stable porous substrate material. CVD treatment at 250°C has been investigated for porous BN, but selectivity did not develop. Therefore, we focused on atmospheric pressure plasma as a treatment method. The objective of this study is to develop a membrane with high hydrogen selective permeance by immersion in silicon alkoxide after plasma treatment. After plasma treatment for 100 s, the H2 permeance was 3.52×10−6 [mol m−2 s−1 Pa−1] and the H2/N2 permeance ratio was 18.25. Since molecular hydrogen can pass between the BN crystal faces, it is considered that silica reacted with the hydroxy groups formed on BN by plasma treatment and blocked the space between crystals. Therefore, it is suggested that the performance of the separation membrane changes depending on the number and distribution of hydroxyl groups by plasma treatment, and further stabilization is needed.

Effects of Phosphorus Doping on Amorphous Boron Nitride's Chemical, Sorptive, Optoelectronic, and Photocatalytic Properties.

Amorphous porous boron nitride (BN) represents a versatile material platform with potential applications in adsorptive molecular separations and gas storage, as well as heterogeneous and photo-catalysis. Chemical doping can help tailor BN's sorptive, optoelectronic, and catalytic properties, eventually boosting its application performance. Phosphorus (P) represents an attractive dopant for amorphous BN as its electronic structure would allow the element to be incorporated into BN's structure, thereby impacting its adsorptive, optoelectronic, and catalytic activity properties, as a few studies suggest. Yet, a fundamental understanding is missing around the chemical environment(s) of P in P-doped BN, the effect of P-doping on the material features, and how doping varies with the synthesis route. Such a knowledge gap impedes the rational design of P-doped porous BN. Herein, we detail a strategy for the successful doping of P in BN (P-BN) using two different sources: phosphoric acid and an ionic liquid. We characterized the samples using analytical and spectroscopic tools and tested them for CO2 adsorption and photoreduction. Overall, we show that P forms P-N bonds in BN akin to those in phosphazene. P-doping introduces further chemical/structural defects in BN's structure, and hence more/more populated midgap states. The selection of P source affects the chemical, adsorptive, and optoelectronic properties, with phosphoric acid being the best option as it reacts more easily with the other precursors and does not contain C, hence leading to fewer reactions and C impurities. P-doping increases the ultramicropore volume and therefore CO2 uptake. It significantly shifts the optical absorption of BN into the visible and increases the charge carrier lifetimes. However, to ensure that these charges remain reactive toward CO2 photoreduction, additional materials modification strategies should be explored in future work. These strategies could include the use of surface cocatalysts that can decrease the kinetic barriers to driving this chemistry.

Fiber Optic Sensor Coated with Multiple Layers of Hexagonal Boron Nitride Nanosheets (BNNS) for the Detection of Volatile Organic Compounds.

Nowadays, volatile organic compound (VOC) detection is imperative to ensure environmental safety in industry and indoor environments, as well as to monitor human health in medical diagnosis. Gas sensors with the best sensor response, selectivity, and stability are in high demand. Simultaneously, the advancement of nanotechnology facilitates novel nanomaterial-based gas sensors with superior sensor characteristics and low power consumption. Recently, boron nitride, a 2D material, has emerged as an excellent candidate for gas sensing and demonstrated exceptional sensing characteristics for new-generation gas sensing devices. Herein, ultrathin porous boron nitride nanosheets (BNNSs) with large lateral sizes were synthesized using a facile synthesis approach, and their material characteristics were investigated utilizing a variety of analytical techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. A BNNS-coated cladding-modified fiber optic sensor (FOS) probe was prepared and employed for VOC (ammonia, ethanol, and acetone) sensing across concentrations varying from 0 to 300 ppm. The BNNSs-coated FOS demonstrated better selectivity toward 300 ppm ammonia, and specifically annealed BNNSs displayed a maximum sensor response of 55% along with a response/recovery times of 15 s/34 s compared to its counterparts. The superior ammonia sensing performances could be attributed to the formation of ultrathin nanosheets and a porous surface with slit-like features in hexagonal boron nitride.

Cement based nanofiltration membrane of porous boron nitride and graphene oxide for effective oil/water separation

The development of effective filters for crude oil/water separation presents a critical environmental challenge in the face of oil spills. Porous membrane separation stands as a vital technique for removing organic solvents, oils, and dyes from water. In this study, we designed and fabricated a nanofiltration membrane composed of graphene oxide (GO) and boron nitride (BN) incorporated into a cement-based matrix to enhance the selectivity and efficiency of unidirectional flux transportation. The integration of GO, with its rich functional groups, and BN, known for its hydrophobic properties, within the cement matrix, resulted in an improved water permeation rate. Moreover, the inclusion of BN flakes in the cement matrix significantly enhances its mechanical strength, reaching up to 15.93 MPa (∼35 % greater than pristine cement), establishing it as a robust nanofiltration membrane for simultaneous flux enhancement and water purification. This innovative filter demonstrated remarkable separation efficiency, achieving up to 99 % oil removal while allowing the passage of water. To gain a deeper understanding of our experimental findings, we conducted ab initio investigations into the adsorption behavior of water and oil components, including ethanethiol, thiophene, and toluene molecules, on h-BN, GO, and their defective structures (Stone-Wales defect). Our results affirm that porous h-BN and GO nanosheets, characterized by their high specific surface areas, exhibit remarkable sorption capabilities. This nanoengineered membrane showcases substantial adsorption capacity alongside physisorption characteristics suitable for recycling, thereby holding significant potential for the development of functional porous structural materials in the realm of high-performance, cost-effective, and environmentally sustainable water treatment solutions.

Separation and reutilization of heavy metal ions in wastewater assisted by p-BN adsorbent

Extracting heavy metal ions from wastewater has significant implications for both environmental remediation and resource preservation. However, the conventional adsorbents still suffer from incomplete ion removal and low utilization efficiency of the recovered metals. Herein, we present an extraction and reutilization method assisted by porous boron nitride (p-BN) containing high-density N atoms for metal recovery with simultaneous catalyst formation. The p-BN exhibits stable and efficient metal adsorption performance, particularly for ultra-trace-level water purification. The distribution coefficients towards Pb2+, Cd2+, Co2+ and Fe3+ can exceed 106 mL g−1 and the residual concentrations that reduced from 1 mg L−1 to 0.8–1.3 μg L−1 are much lower than the acceptable limits in drinking water standards of World Health Organization. Meanwhile, the used p-BN after Co ion adsorption can be directly adopted as a high-efficiency catalyst for activating peroxymonosulfate (PMS) in organic pollutant degradation without additional post-treatment, avoiding the secondary metal pollution and the problems of neglected manpower and energy consumption. Moreover, a flow-through multistage utilization system assisted by p-BN/polyvinylidene fluoride (PVDF) membrane is constructed for achieving both metal ion separation and reutilization in the removal of organic pollutants, providing a new avenue for sustainable wastewater remediation.

A novel study on the adsorption of low concentration Cd(II) and Ni(II) using porous boron nitride: effectiveness, coexisting anion interference, and regeneration

A novel study on the adsorption of low concentration Cd(II) and Ni(II) using porous boron nitride: effectiveness, coexisting anion interference, and regeneration

Oxygen-Activated Boron Nitride for Selective Photocatalytic Coupling of Methanol to Ethylene Glycol.

The controllable photocatalytic C-C coupling of methanol to produce ethylene glycol (EG) is a highly desirable but challenging objective for replacing the current energy-intensive thermocatalytic process. Here, we develop a metal-free porous boron nitride catalyst that demonstrates exceptional selectivity in the photocatalytic production of EG from methanol under mild conditions. Comprehensive experiments and calculations are conducted to thoroughly investigate the reaction mechanism, revealing that the OB3 unit in the porous BN plays a critical role in the preferential activation of C-H bond in methanol to form ⋅CH2OH via a concerted proton-electron transfer mechanism. More prominent energy barriers are observed for the further dehydrogenation of the ⋅CH2OH intermediate on the OB3 unit, inhibiting the formation of some other by-products during the catalytic process. Additionally, a small downhill energy barrier for the coupling of ⋅CH2OH in the OB3 unit promotes the selective generation of EG. This study provides valuable insights into the underlying mechanisms and can serve as a guide for the design and optimization of photocatalysts for efficient and selective EG production under mild conditions.

Oxygen‐Activated Boron Nitride for Selective Photocatalytic Coupling of Methanol to Ethylene Glycol

AbstractThe controllable photocatalytic C−C coupling of methanol to produce ethylene glycol (EG) is a highly desirable but challenging objective for replacing the current energy‐intensive thermocatalytic process. Here, we develop a metal‐free porous boron nitride catalyst that demonstrates exceptional selectivity in the photocatalytic production of EG from methanol under mild conditions. Comprehensive experiments and calculations are conducted to thoroughly investigate the reaction mechanism, revealing that the OB3 unit in the porous BN plays a critical role in the preferential activation of C−H bond in methanol to form ⋅CH2OH via a concerted proton‐electron transfer mechanism. More prominent energy barriers are observed for the further dehydrogenation of the ⋅CH2OH intermediate on the OB3 unit, inhibiting the formation of some other by‐products during the catalytic process. Additionally, a small downhill energy barrier for the coupling of ⋅CH2OH in the OB3 unit promotes the selective generation of EG. This study provides valuable insights into the underlying mechanisms and can serve as a guide for the design and optimization of photocatalysts for efficient and selective EG production under mild conditions.

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.

Ball milling synthesis of Fe3O4 nanoparticles-functionalized porous boron nitride with enhanced cationic dye removal performance.

Enhancement of the adsorption performance and recyclability of adsorbents is a crucial aspect of water treatment. Herein, we used one-dimensional porous boron nitride (PBN) as a carrier to load Fe3O4 nanoparticles for the preparation of Fe3O4 nanoparticles-functionalized porous boron nitride (Fe3O4/PBN) via a ball milling method. The high-energy ball milling promoted the creation of a negatively charged PBN surface and facilitated the uniform distribution of Fe3O4 nanoparticles on the surface of PBN. The adsorption performance of Fe3O4/PBN toward cationic dyes could be significantly improved while no enhancement was observed for anionic dyes. The great adsorption performance of Fe3O4/PBN is due to its surface functional groups and surface defects formed in the ball milling process. Moreover, the strong interaction force between Fe3O4/PBN and cationic dyes promotes rapid initial adsorption due to their negatively charged surface. Magnetic measurements demonstrated that Fe3O4/PBN is superparamagnetic. The composites with low loadings of Fe3O4 nanoparticles could be quickly separated from the aqueous solution under a low applied magnetic field, improving their recyclability. This work highlights the role of ball milling in improving the adsorption performance of Fe3O4/PBN and greatly promotes the practical application of Fe3O4/PBN in the field of environmental purification.

Highly Porous Boron Nitride as a Metal-Free Heterogeneous Catalyst for Cycloaddition of CO2 to Epoxides

Boron nitride has received much attention as an emerging heterogeneous catalyst. Porous boron nitride catalysts were synthesized using boric acid (B) and urea (U) at various molar ratio via pyrolysis...

Boron nitride microfiber reinforced polyacrylic acid hydrogels with excellent self-adhesion, fast pH response, and strain sensitivity.

Hydrogels are widely utilized in the sensor field, but their inadequate adhesion presents a significant obstacle. Herein, a new multifunctional BNMFs/PAA composite hydrogel was prepared via the incorporation of one-dimensional porous boron nitride microfibers (BNMFs) and polyacrylic acid (PAA) hydrogels. BNMFs, as a reinforcing filler, play a very important role in enhancing the properties of the composite hydrogels. In particular, the porous micrometer structure plays a unique role in improving the adhesion properties of PAA hydrogels. The steric hindrance and the rich hydroxyl functional groups coming from BNMFs are key factors for the excellent adhesion of the composite hydrogels. The composite hydrogels show strong adhesion to various substrate materials. For iron plates and biological tissues, the adhesion energy can reach 1377 J m-2 and 317 J m-2, respectively. In addition, the developed BNMFs/PAA composite hydrogels exhibit excellent mechanical properties. The fracture strain of the composite hydrogels is increased by 2.4 times compared to pure PAA hydrogels. The hydrogen bonds formed between BNMFs and PAA are conducive to the mechanical properties of the BNMFs/PAA composite hydrogels. Meanwhile, BNMFs as fillers play a role in carrying and dissipating force. Furthermore, the BNMFs/PAA composite hydrogels have excellent strain and pH response characteristics. This is because the crosslinking network of the composite hydrogels becomes loose after the addition of BNMFs, resulting in rapid ion transport pathways. Therefore, the developed BNMFs/PAA composite hydrogels will have broad application prospects in the fields of motion monitoring, intelligent skin and biological adhesives.

Easy preparation of porous boron nitride with excellent cycle stability for water purification

The structure of hexagonal boron nitride (h-BN) is similar to that of graphite, which has strong reducibility and adsorbability. In this study, boron nitride precursor was made using melamine as a nitrogen source and boric acid as a source of boron under hydrothermal conditions, and the precursor was subsequently burned to create porous BN at a certain temperature. Effect of NH4HCO3 content on the porosity and structure of the materials was investigated to improve the adsorption performance of h-BN. The morphology, composition and structure of the materials were analyzed by scanning electron microscope, energy spectrum analyzer and X-ray diffraction. According to the findings, BN has a greater specific surface area of 169.29 m2/g under optimal preparation circumstances, which increases its capacity for adsorption. When the concentration of methylene blue was 200 mg/L, the adsorption capacity of the material reached to 377 mg/g in 120 min. In addition, the remarkable anti-oxidation and structural stability of the employed BN materials make it simple to regenerate them through burning or ethanol elution. In five cycles, the adsorption performance did not decrease.

Porous boron nitride nanosheets via pyrolysis of melamine phosphate and borate assembly for water purification

Development of porous micro-nanomaterials with excellent physical and chemical stability as adsorbents for effective water cleanup still has huge practical implications. Here, hierarchically porous boron nitride nanosheets (BNNSs) with abundant active groups (-OH and –NH2) and defective structures were prepared via the incorporation of phosphoric acid into melamine borate (M·2B) to form a melamine phosphate and borate assembly and subsequent pyrolysis. Phosphoric acid can interact with melamine through hydrogen bonding, which not only changes the micromorphology of porous BN materials but also regulates their chemical compositions and bonding states. The resulting porous BNNSs show a specific surface area as high as 1477.923 m2/g and a large pore volume. Encouraged by these characteristics, the resulting porous BNNSs exhibit remarkable adsorption capabilities for methylene blue (MB) in alkaline solution up to 750 mg/g and oxytetracycline (OTC) in acidic solution up to 128 mg/g. Additionally, they have excellent cyclic adsorption performance, suggesting a high practical value in wastewater purification. Therefore, this work not only presents the practical application of porous BNNSs in sewage treatment but also provides a designing scheme for preparing variety micro- and nano-BN materials by regulating and controlling the transformation of melamine salts.

The outstanding electrochemical performance of porous hexagonal boron nitride as a K-ion battery anode

Within the current piece of research, we propose a porous model of hexagonal boron nitride (h-BN) monolayer (h-BNML) through DFT calculations in order develop an anode material for KIBs. We in particular focused on the impact of the pore on the diffusion of K ions and upon the storage process. We created the porous model of the h-BNML by using a pure h-BNML structure via the removal of B atoms which mimics the formation of the pore. Based on the DFT calculations, there was no change in the original planar structure of the h-BNML after the formation of the pore. There was a dramatic change in the electronic and structural attributes of the h-BNML indie the poor based on the introduced vacancies, which allowed the K-ion to adhere effectively within the pore. Based calculations demonstrated the interaction between the K ions and the pores through electrostatic attraction. The model exhibited the ability to keep a high number of K ions at its surface without any change in the initial planar structure of h-BN, which was closely associated with an increased theoretical specific capacity, which increased with porosity. Hence, the pore formation increased the diffusion of K ions in comparison with the pure h-BNML. This can be insightful to designing enhanced anode materials for KIBs. Finally, the current work can provide insights into tailoring porous BN materials for application in KIBs.

2D/2D combination effects of pBN/gC3N4/TiO2 nanocomposites for photocatalytic CO2 conversion with alternative cationic scavengers

In this study, a series of pBN/gCN and pBN/gCN/TiO2 ternary nanocomposites was successfully fabricated by integrating 2D porous boron nitride and 2D graphitic carbon nitride with TiO2 using different amounts of gCN. First-principles DFT calculations were used for the first time to explore the electronic structure and electron flow in the ternary nanocomposites. The successful junctions of pBN/gCN/TiO2 were determined by analytical techniques, and all the results agreed that pBN, gCN, and TiO2 had interfacial connections with the efficient separation of photogenerated electrons and holes, thereby supplying plentiful photoinduced electrons to CO2R. In the photocatalytic CO2 reduction test, the light source was the principal component of the reactor; thus, we used visible light of different intensities (15 W, 75 W, and 100 W). In NaHCO3 solvent with a TEA electron donor, the CH3OH rates over TBCN2 were 13.79, 15.59, and 14.02 %, respectively. The enhanced efficiency of photocatalytic CO2 reduction is not only explained by the excellent capture of CO2 and the activation performance of TBCN2 with 2D/2D junctions, but also by the rapid charge separation and transfer of photogenerated charge carriers. Hence, this work demonstrates the use of 2D pBN and gCN with TiO2 ternary nanocomposites as novel and efficient catalysts for CO2R.