Nitride Aerogels Research Articles

Unveiling N-doped carbon nitride aerogel for efficient electrocatalytic water splitting application

Unveiling N-doped carbon nitride aerogel for efficient electrocatalytic water splitting application

Robust and Density Tunable Kevlar/Hexagonal Boron Nitride Microribbon Aerogels with Excellent Thermal, Mechanical, and Oil-Absorption Properties.

With rapid advancements in aerospace and supersonic aircraft technology, there is a growing demand for multifunctional thermal protective materials. Aerogels, known for their low density and high porosity, have garnered significant attention in this regard. However, developing a lightweight multifunctional aerogel that combines exceptional thermal and mechanical properties through a straightforward and time-efficient method remains a significant challenge. Herein, a facile and universal approach is developed for the preparation of Kevlar/hexagonal boron nitride (h-BN) aerogels, in which a spin-assisted method is applied to create robust microribbons and further accelerate solvent displacement. The resulting microribbon scaffold, with its entangled nanofiber-nanosheet morphologies, exhibits sufficient strength to prevent volume shrinkage during drying, thereby allowing precise control over aerogel density. The porous hybrid aerogels, featuring controllable geometric characteristics and tailored densities ranging from 6.9 to 100 mg cm-3, can be successfully fabricated. These aerogels exhibit excellent thermal insulation properties, and the thermal conductivities of the as-prepared KBX aerogels have a wide distribution in the range of 0.0269-0.0450 W m-1 k-1. The thermal stability of the hybrid aerogels is enhanced to 566 °C. Moreover, the resulting hybrid aerogels exhibit an ultrahigh bearing ratio, supporting more than 2000 times their own weight while maintaining stable structural integrity. These aerogels also demonstrate high compressive strength, hydrophobicity, and excellent sorption performance for various oils and solvents. Additionally, the oil-saturated aerogels can be easily recovered through heat treatment or combustion in air. The features endow hybrid Kevlar/h-BN aerogels with significant potential for applications in thermal management, environmental protection, and neutron protection.

Preparation of three dimensional boron nitride-aluminum oxide dual thermal network resin-based composite materials and their performance study

With the gradual miniaturization and integration of electronic devices, the design and development of new high thermal conductivity polymer-based composite materials are crucial for enhancing the performance of modern electronic devices. In this study, three-dimensional boron nitride (3D-BN) aerogels with vertically aligned structures were prepared using the ice templating method, serving as the primary thermal conductive network. Subsequently, aluminum oxide (Al2O3)/epoxy resin (EP) nanofluids were infiltrated into the aerogel’s air pores using vacuum impregnation. The Al2O3 particles in contact with each other formed the secondary thermal conductive network. Thus, a 3D BN-Al2O3/EP composite material with a dual thermal conductive network structure was successfully fabricated. The composite material exhibited a high thermal conductivity coefficient of 1.077 Wm−1K−1 when loaded with 17.67 wt% BN and 26.23 wt% Al2O3, representing a 496 % increase compared to pure EP and a 211 % increase compared to 3D-BN/EP composite materials. Furthermore, this composite material demonstrated excellent thermal stability and mechanical properties. This work provides a new direction for designing novel polymer-based composite materials with low filler loading and high thermal conductivity performance.

Modification of boron nitride aerogels with APTES for enhanced iodine capture performance

Development of effective iodine capture materials and techniques is crucial for addressing the diverse applications of iodine and its significance in various contexts, including nuclear pollution control. This study presents the creation of a new 3-Aminopropyltriethoxysilane (APTES)-modified boron nitride (BN) aerogel designed for effective iodine capture. The internal structural units of BN aerogel, specifically the one-dimensional BN fibers, have been successfully functionalized with amine groups, resulting in the formation of an amine-rich SiOx capping layer on the surface of these fibers. The APTES modification not only establishes a stable connection within the internal BN fibers network but also imparts the material with a significant number of iodine capture sites. The resulting aerogel demonstrates an impressive iodine vapor capture capacity of 313.64 wt% at 350 K and atmospheric pressure, and up to 1028.96 mg/g in iodine/n-hexane solution, surpassing the capabilities of pure BN aerogel and most existing iodine capture materials. The excellent iodine capture performance of APTES-modified BN aerogel suggests its promising potential for future applications in iodine capture.

Dual Cross‐Linked Magnetic MXene Aerogel with High Strength and Durability Enables Multifunctionality

AbstractThe construction of lightweight yet robust, durable magnetic transition metal carbides and/or nitride (MXene) aerogels is highly desired for assembling high‐performance, multifunctional architectures. However, the fabrication and application of magnetic MXene aerogels is severely restricted by their inferior mechanical strength and poor water/oxygen resistance. Here, sustainable cellulose nanofibrils (CNFs) are employed for assisting in the physical and chemical dual cross‐linking to strongly bind the MXenes and MOF‐derived magnetic nanoparticles. The dual‐crosslinked magnetic MXene aerogels (D‐MMAs) achieve a density as low as 12 mg cm−3, and acquire a significantly improved mechanical strength of up to 1311% over physically crosslinked ones, as well as remarkably improved hydrophobicity, and oxidation stability. Furthermore, the multifunctional integration of efficient and tunable electromagnetic wave (EMW) absorption, remarkable photothermal conversion, thermal insulation, prominent oil‐water separation, thin/thick oil and dye absorption capability, and the remote magnetic controllability is accomplished. Notably, the D‐MMA performs a maximum absorption intensity of −63.9 dB, and accomplishes a specific reflection loss of −1105 dB mm−1, comparable to the best MXene‐based EMW absorbers ever reported. Given its facile, scalable, and sustainable manufacturing approach, the multifunctional D‐MMAs hold great application prospects in various fields of next‐generation electronics, special equipment protection, defense, and aerospace.

Laser Ablation‐Induced Boron Nitride Aerogels with Intrinsic Photoluminescence for Efficient Information Encryption

AbstractBoron nitride (BN) aerogels, dual interconnecting network of BN nanoscale building blocks, and plenty of air within these nanoscale building blocks, have great potential in many emerging fields. However, fast synthesis and emerging applications, e.g., information encryption, are still challenging for advancing BN aerogels. Herein, intrinsic photoluminescent BN aerogels with programmable patterns are developed via laser ablating of melamine diborate (M2B) aerogel. The obtained BN aerogel exhibited typical hollow‐microsphere structures and blue fluorescence phenomenon, which are totally different from BN aerogels reported elsewhere. This BN aerogel exhibited excellent thermal insulation properties (0.027 W mK−1), transient fluorescence feature (3 ns average radiative lifetime), high quantum yield (18.45%), and excellent weather ability (e.g., resistance to high temperature, solar irradiation, and humidness). By programming the laser moving path, different fluorescent patterns (e.g., various security labels, secret matching keys, quick response codes) of BN aerogels can be processed, which promises excellent information encryption in the field of Internet of Things, etc. The results may inspire researchers to fabricate more aerogels with this fast laser‐ablation strategy and the resulting intrinsic fluorescent BN aerogels may find significant applications in some emerging fields.

Nanoflower-like graphitic carbon nitride aerogel: Artful cyanuric acid-controlled synthesis and enhanced photocatalytic hydrogen evolution activity

The previously reported studies on cyanuric acid-assembly strategy usually ignores the promoting function of cyanuric acid in the production of g-C3N4, limiting the development of molecular assembly strategies. In this study, a cyanuric acid-controlled synthesis strategy involving the pre-assembly of cyanuric acid with melamine and subsequent one-step calcination was developed to produce a three-dimensional (3D) nanoflower-like graphitic carbon nitride (g-C3N4) aerogel. Some cyanuric acid molecules underwent a polycondensation reaction with melamine during the pre-assembly process and finally polymerized into the g-C3N4 structure during subsequent calcination. Meanwhile, the remaining cyanuric acid molecules assembled with melamine via hydrogen-bond interactions and underwent incomplete decomposition during subsequent calcination, which not only promoted the production of 3D nanoflower-like aerogel structures, but also introduced the carbonyl (CO) and hydroxyl (–OH) groups onto the g-C3N4 surface, resulting in the successful generation of a 3D nanoflower-like oxygen-modified g-C3N4 aerogel. Moreover, the fabricated g-C3N4 aerogel exhibited a greatly enhanced H2 production rate (1573 μmol h−1 g−1), which is ∼ 6.6 times higher than that of bulk g-C3N4 (239 μmol h−1 g−1) owing to the synergistic promotion function of ultrathin nanoflower-like aerogel and oxygen modification structures. This strategy provides a theoretical basis for the development of highly efficient g-C3N4 photocatalysts via molecular assembly.

Boron nitride aerogels incorporated with metal nanoparticles: Multifunctional platforms for iodine capture and detection

Radioactive iodine vapors produced by nuclear fission can pose a significant risk to human health and the environment. Effective monitoring of iodine vapor leakage, capture and storage of radioactive iodine vapor are of great importance for the safety of the nuclear industry. Herein, we report a novel structure-function integrated solid iodine vapor adsorbent based on metal-modified boron nitride (BN) aerogel. Metal-modified BN aerogels incorporated with Cu/Ag nanoparticles (named as BN-Cu and BN-Ag, respectively) are successfully prepared by a metal-induced, ultrasonic-assisted, and in-situ transformation method. The metal-modified BN aerogels show improved mechanical properties in both of the maximum stress and residual deformation. Remarkably, due to the greatly enhanced “host-guest” and “guest-guest” effects by the introduction of metal nanoparticles, the BN-Cu and BN-Ag aerogels exhibit record-breaking iodine vapor adsorption capacities among inorganic adsorbents (1739.8 and 2234.13 wt% respectively), which are even higher than that of most organic adsorbents. Furthermore, an integrated iodine adsorption detection device based on metal-modified aerogels is constructed to realize real-time detection of the electrical properties of aerogels during iodine adsorption. This work provides a foundation for the development of BN aerogels as multifunctional platforms for effective iodine capture and detection. It also introduces new ideas for the use of structural-functional integrated materials in the prevention and control of radioactive iodine pollution.

Super‐White Boron Nitride Aerogel‐Enabled High‐Energy Laser Irradiation Protection

AbstractAerogels are ultralight solid materials with three‐dimensional interconnected porous structures that offer considerable advantages for various protective applications. Lasers have led to various technological revolutions in aerospace, medical science, and industrial manufacturing. However, shielding against high‐energy laser irradiation using aerogels has rarely been reported. A super‐white (reflectivity >98%) boron nitride (BN) aerogel constructed using BN nanoribbons is developed in this study for high‐energy laser protection. Large numbers of BN nanoribbons serve as randomized and disordered optical nanobarriers for intense backlight scattering, which contribute to high broadband reflectivity. Combined with the low thermal conductivity of the aerogel structure and the excellent high‐temperature stability of BN, the resulting BN aerogel exhibits a high protective threshold of 2.1 × 104 W cm−2. Moreover, the BN aerogel possesses a soft porous network and a low thermal expansion coefficient, which is promising for tolerating the thermal stress and shock of local high‐temperature fields caused by laser irradiation. The successful laser shielding by the super‐white BN aerogel may be helpful for designing and fabricating advanced aerogel‐based lightweight anti‐laser materials.

Ultrafast self-assembly of supramolecular hydrogels toward novel flame-retardant separator for safe lithium ion battery

Traditional polyolefin separators for lithium-ion batteries (LIBs) often experience limited thermal stability and intrinsic flammability, resulting in great safety risks during their usage. Therefore, it is highly important to develop novel flame-retardant separators for safe LIBs with high performance. In this work, we report a flame-retardant separator derived from boron nitride (BN) aerogel with a high BET surface area of 1127.3 m2 g−1. The aerogel was pyrolyzed from a melamine-boric acid (MBA) supramolecular hydrogel, which was self-assembled at an ultrafast speed. The in-situ evolution details of the nucleation-growth process of the supramolecules could be observed in real-time using a polarizing microscope under ambient conditions. The BN aerogel was further composited with bacterial cellulose (BC) to form a BN/BC composite aerogel with excellent flame-retardant performance, electrolyte-wetting ability and high mechanical property. By using the BN/BC composite aerogel as the separator, the developed LIBs exhibited high specific discharge capacity of 146.5 mAh g−1 and excellent cyclic performance, maintaining 500 cycles with a capacity degradation of only 0.012% per cycle. The high-performance flame-retardant BN/BC composite aerogel represents a promising candidate for separators not only in LIBs but also in other flexible electronics.

Chemically bonded multi-nanolayer inorganic aerogel with a record-low thermal conductivity in a vacuum.

Inorganic aerogels have exhibited many superior characteristics with extensive applications, but are still plagued by a nearly century-old tradeoff between their mechanical and thermal properties. When reducing thermal conductivity by ultralow density, inorganic aerogels generally suffer from large fragility due to their brittle nature or weak joint crosslinking, while enhancing the mechanical robustness by material design and structural engineering, they easily sacrifice thermal insulation and stability. Here, we report a chemically bonded multi-nanolayer design and synthesis of a graphene/amorphous boron nitride aerogel to address this typical tradeoff to further enhance mechanical and thermal properties. Attributed to the chemically bonded interface and coupled toughening effect, our aerogels display a low density of 0.8mg cm-3 with ultrahigh flexibility (elastic compressive strain up to 99% and bending strain up to 90%), and exceptional thermostability (strength degradation <3% after sharp thermal shocks), as well as the lowest thermal conductivities in a vacuum (only 1.57mW m-1 K-1 at room temperature and 10.39mW m-1 K-1 at 500°C) among solid materials to date. This unique combination of mechanical and thermal properties offers an attractive material system for thermal superinsulation at extreme conditions.

Constructing BN/BN composite aerogels with strong hydrophobic properties and improved heat transfer capability

Boron nitride (BN) aerogels is a class of three-dimensional (3D) hierarchical network structure assembled from BN micro/nanostructures. The construction of BN/BN composite aerogel by introducing of BN micro/nano-structural units into the 3D BN aerogel scaffold provides an effective strategy for obtaining BN aerogel with improved all-round properties. Here, a novel kind of BN/BN composite aerogels has been developed by vacuum impregnation of ammonia borane (AB) into fiber-based BN aerogels, followed by high-temperature pyrolysis. The introducing of AB into BN aerogels makes the formation of unique AB/BN composite aerogels, and the high-temperature decomposition of AB results in the obtaining of a series of multifunctional composites, i.e. BN/BN composite aerogels. As compared with the porous BN microfibers in original BN aerogel, the self-assembled fibers in BN/BN composite aerogel are densely covered with high crystalline BN nanoflakes, which are generated by the AB decomposition. The obtained BN/BN composite aerogels have shown excellent thermal stability, significantly improved hydrophobic effect and heat transfer capability. This work provides a new idea for the future research and development of BN composite aerogels.

Environmentally friendly self-assembly strategy to fabricate novel S and O co-doped carbon nitride aerogel photocatalyst with improved photocatalytic degradation capability

A novel S and O co-doped g-C3N4 aerogel (remarked as SOCNA) photocatalyst is devised and fabricated via hydrothermal shearing combined with self-assembly strategy without applying any cross-linking reagents and harmful solvents but water. SOCNA with different morphologies and O doping amounts are explored by adjusting hydrothermal time, and further the shearing and assembly mechanisms of SOCNA are elucidated. SOCNA not only displays superior removal efficiencies for the colored dyes methylene blue (97.66 %, 15 min) and rhodamine B (96.43 %, 30 min), but also the degradation rate of colorless tetracycline hydrochloride reaches as high as 92.22 % within 40 min. The influence of different concentrations and pH values of the liquids on the photo-degradation efficiencies of three pollutants by using SOCNA is systematically discussed. Compared with ordinary g-C3N4, the strengthened photocatalytic activity of SOCNA can be attributed to large surface area, more charge and mass transfer channels, regulating the energy band structure via S and O doping, broadening the spectral capture range and prolonging the life of photo-induced carriers. Besides, the degradation cycle measurements of three pollutants reveal that SOCNA holds recyclable stability. Hence, the study offers an efficient and environmentally friendly strategy for the development of other heteroatom co-doped aerogel photocatalysts.

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.

High thermal conductive shape-stabilized phase change materials based on water-borne polyurethane/boron nitride aerogel

Phase change materials (PCMs) applied in energy storage and temperature control system are important for energy conservation and environmental protection. In this work, structure-adjustable water-borne polyurethane (WPU)/boron nitride (BN) aerogels were synthesized via directional freeze-drying method, and used as supporting scaffolds to confine paraffin wax (PW) and obtain composite phase change materials. The three-dimensional (3D) porous thermal conductivity network of BN was derived by the in-situ ice crystal mound in aerogel, which endows the PW/WPU/BN composite PCM-2.5 with high thermal conductivity (0.96 W m−1 K−1) and high energy storage density (140.04 J/g). Shape-stabilized PCMs with high thermal conductivity and excellent electrical insulation prepared by the simple method have great potential for the thermal management of electronic products.

Scalable Fabrication of Thermally Conductive Layered Nacre-like Self-Assembled 3D BN-Based PVA Aerogel Framework Nanocomposites.

In this study, three-dimensional (3D) polyvinyl alcohol (PVA)/aligned boron nitride (BN) aerogel framework nanocomposites with high performance were fabricated by a facile strategy. The boron nitride powder was initially hydrolyzed and dispersed with a chemically crosslinked plasticizer, diethyl glycol (DEG), in the PVA polymer system. The boron nitride and DEG/PVA suspensions were then mixed well with different stoichiometric ratios to attain BN/PVA nanocomposites. Scanning electron microscopy revealed that BN platelets were well dispersed and successfully aligned/oriented in one direction in the PVA matrix by using a vacuum-assisted filtration technique. The formed BN/PVA aerogel cake composite showed excellent in-plane and out-of-plane thermal conductivities of 0.76 W/mK and 0.61 W/mK with a ratio of BN/PVA of (2:1) in comparison with 0.15 W/mK for the pure PVA matrix. These high thermal conductivities of BN aerogel could be attributed to the unidirectional orientation of boron nitride nanoplatelets with the post-two days vacuum drying of the specimens at elevated temperatures. This aerogel composite is unique of its kind and displayed such high thermal conductivity of the BN/PVA framework without impregnation by any external polymer. Moreover, the composites also presented good wettability results with water and displayed high electrical resistivity of ~1014 Ω cm. These nanocomposites thus, with such exceptional characteristics, have a wide range of potential uses in packaging and electronics for thermal management applications.

Compressive and thermally stable boron nitride aerogels as multifunctional sorbents.

Boron nitride (BN) aerogels are three-dimensional bulk materials with exceptional performances in a wide range of areas. However, detailed investigations into the relationship of synthesis, structure, and properties are rare. This study demonstrates the feasibility of tuning the performance of the aerogel by simply altering the relative amount of the precursors in the synthesis, which subsequently leads to the formation of aerogels with distinctive properties such as specific surface areas, porosity, and compressibility. The applications of these structurally different aerogels are exemplified by investigating in a series of important industrial-related areas, such as oil absorption/desorption, direct combustion, adsorptive desulfurisation, and CO2 capture. The study raises the application prospects of BN aerogels in gas-phase catalysis and thermal superinsulation materials.

Synthesis of Nanostructured Boron Nitride Aerogels by Rapid Pyrolysis of Melamine Diborate Aerogels via Induction Heating: From Composition Adjustment to Property Studies

Synthesis of Nanostructured Boron Nitride Aerogels by Rapid Pyrolysis of Melamine Diborate Aerogels via Induction Heating: From Composition Adjustment to Property Studies

Calcium-Doped Boron Nitride Aerogel Enables Infrared Stealth at High Temperature Up to 1300 °C

HighlightsA calcium-doped boron nitride (Ca-BN) aerogel was synthesized by introducing Ca into crystal structure of BN building blocks.The aerogels exhibited superior high-temperature stability and could resist the burning of butane flame (~1300 °C) in air atmosphere.Ca-BN aerogel, together with Al foil, can effectively hide thermal target at high temperature up to 1300 °C.

Ice template method assists in obtaining carbonized cellulose/boron nitride aerogel with 3D spatial network structure to enhance the thermal conductivity and flame retardancy of epoxy-based composites

Ice template method assists in obtaining carbonized cellulose/boron nitride aerogel with 3D spatial network structure to enhance the thermal conductivity and flame retardancy of epoxy-based composites