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Hexagonal boron nitride (h -BN) materials with excellent physicochemical stability and processibility have been considered as promising engineering materials. However, their practical applications are rather limited by the difficulty in constructing the well-bonded h -BN ceramic. Herein, we present a reaction welding strategy for facile preparation of well-bonded h -BN fibers (BNFs) network by using ethanolamine (ETA) containing alcoholic hydroxyl and primary amine groups as crosslinking agent. The formed >B-O-H 2 C-H 2 C-H 2 N|→B< bond bridges through the esterification and intramolecular coordination (N|→B) reactions between ETA molecules and BNFs containing surface hydroxyls, play an essential role in the construction of the thermodynamically stable >B-N-B< covalent bond between BNFs. Based on this synthetic strategy and a room-temperature molding process followed by a calcination step, a series of resilient BNFs ceramics with high processibility, typical diamagnetism, low dielectric constant (∼ 2.1) and loss, good resistance to temperature different, corrosion, oxidation and abrasion are produced. Besides, they also exhibit excellent strain and damage tolerance, the maximum compression strain and strength can reach up to 38% and ∼ 33 MPa, respectively. Significantly, the deliberately designed BNFs vessel can be successfully used for the alloying of high melting point metals, showing both structural/chemical robustness and good reusability. This ingenious design for well-bonded BNFs network not only is a good model for exploring the welding way for h -BN powders, but also opens up numerous opportunities for practical applications. • A well-bonded boron nitride fibers network is prepared via chemical welding approach. • Ethanolamine (ETA) with bifunctional groups is selected as crosslinking agent. • Bond bridges are formed through esterification and intramolecular coordination reactions. • BNFs ceramics with processibility and excellent physicochemical stability are obtained. [ABSTRACT FROM AUTHOR]

Because they have a high application potential in the thermal management of insulation environments, high-quality hexagonal boron nitride (h-BN)-based multiphase ceramics have been highly desired. However, so far, their synthesis is still full of challenges. Here, a kind of boron nitride nanosheets (BNNSs)/glass (GS) composite ceramics was prepared by a pressureless sintering method at a lower temperature of 900 °C. Due to a tightly bonded interaction between BNNSs and GS, the formed BNNSs/GS ceramics exhibit excellent multifunction performance. They have an outstanding compressive strength in the range of 19 ∼ 64 MPa and Vickers hardness ranging from 50 to 179 HV. For the BNNSs/GS ceramics with BNNS's filling fraction of 90 wt%, their maximum side-surface TC values are 12.01 ± 0.18 W m−1 K−1 at 25 °C and 13.64 ± 0.37 W m−1 K−1 at 300 °C, respectively. In the ultra-high frequency range of 26.5 ∼ 40 GHz, the dielectric constant values of the BNNSs/GS ceramics are primarily between 2 and 3, and the corresponding loss tangent values are < 0.3. In addition, based on the remarkable integrity of their structure, these BNNSs/GS ceramics exhibit outstanding thermal-shock stability and prominent thermal management capacity during lots of heating/cooling-testing cycles. Therefore, we believe this kind of BNNSs/GS ceramic system will have great application potential in the new-generation thermal management and/or insulation packaging fields. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur (Li‐S) batteries are one of the most promising high‐energy‐density storage systems. However, serious capacity attenuation and poor cycling stability induced by the shuttle effect of polysulfide intermediates can impede the practical application of Li‐S batteries. Herein we report a novel sulfur cathode by intertwining multi‐walled carbon nanotubes (CNTs) and porous boron nitride fibers (BNFs) for the subsequent loading of sulfur. This structural design enables trapping of active sulfur and serves to localize the soluble polysulfide within the cathode region, leading to low active material loss. Compared with CNTs/S, CNTs/BNFs/S cathodes deliver a high initial capacity of 1222 mAh g−1 at 0.1 C. Upon increasing the current density to 4 C, the cell retained a capacity of 482 mAh g−1 after 500 cycles with a capacity decay of only 0.044 % per cycle. The design of CNTs/BNFs/S gives new insight on how to optimize cathodes for Li‐S batteries. [ABSTRACT FROM AUTHOR]

A novel two-step method is developed for the facile preparation of hollow nano-spherical boron nitride (BN). BN nanospheres prepared by the traditional chemical vapor deposition reaction of ammonia and trimethyl borate were hollowed out. The average size of solid BN nanospheres precursor was ~ 130 nm. Boron nitride phase, morphology, and surface functionalization characterization along with the measurement of O content, and surface functionality were used to illustrate the final differences among various cavitating BN nanospheres treated with different gas flows at a higher temperature. Several possible formation mechanisms for the BN cavitating structures were proposed. This work provides direction for the controllable preparation of hollow-type BN particles. [ABSTRACT FROM AUTHOR]

[Display omitted] • BNNSs/rGO heterostructure is synthesized by self-assembly crosslinking approach. • The mediator can suppress the shuttle effect of LiPSs by superior adsorption. • It can markedly catalyze the conversion of liquid-phase LiPSs and solid-phase Li 2 S. • BNNSs/rGO-based Li-S batteries show improved electrochemical reaction kinetics. Lithium-sulfur (Li-S) battery with high theoretical specific capacity (1675 mAh/g), has been deemed as one of the most potential candidates of secondary energy storage system. However, the large-scale applications of Li-S batteries have been obstructed by internally sluggish multi-step redox reaction and terrible shuttle effect of lithium polysulfides (LiPSs). Herein, boron nitride nanosheets/reduced graphene oxide (BNNSs/rGO) heterostructure prepared by self-assembly crosslinking method has been designed to modify commercial separator for Li-S batteries. The hierarchical pores, physical and chemical cross-links within heterostructure can significantly enhance the adsorption capacity for LiPSs, uniquely physical and electronic interaction between BNNSs and rGO can effectively catalyze the conversion of sulfurated species. Benefiting from the synergistic adsorption-catalysis effect, BNNSs/rGO not only greatly inhibits the shuttle behaviors, but also considerably accelerates the electrochemical reaction kinetics for LiPSs and Li 2 S. Attributed to these merits, Li-S battery with BNNSs/rGO heterostructure mediator delivers superiorly reversible capacity as high as 915.0 mAh/g at 1 C. Even at high sulfur loading of 3.9 mg cm−2, the cell delivers ultra-stable specific capacity of 629.1 mAh/g at 1 C, and still maintains 605.5 mAh/g over 500 cycles corresponding to a capacity fade of merely 0.0075% per cycle. [ABSTRACT FROM AUTHOR]

[Display omitted] • B/N co-doping rGO/BNNSs heterostructure is prepared by an in-situ reaction strategy. • The heterostructure has fast thermal diffusion and strong LiPSs-blocking capability. • It can significantly enhance the catalytic conversion of both LiPSs and Li 2 S. • The heterostructure-based Li-S cell delivers advanced rate and cycling performances. The practical applications of lithium-sulfur (Li-S) batteries are obstructed by low sulfur utilization and poor cycling stability caused by notorious shuttle effect of soluble lithium polysulfide (LiPSs) and sluggish redox reaction kinetics. Herein, a creative B/N co-doping reduced graphene oxide/boron nitride nanosheets (B/N co-doping rGO/BNNSs) heterostructure prepared by a facile in-situ pyrolysis reaction strategy, is rationally designed as a multifunctional coating for high-performance Li-S batteries. The modified separator with B/N co-doping rGO/BNNSs displays excellent flexibility, thermal conductivity and electrolyte wettability. The superior shielding effect to LiPSs provided by the high density of B-N, B-C and C-N polar bonds and hierarchical pore structures, not only enhance the utilization of sulfur but also prevent the Li-anode from corrosion by LiPSs. Meanwhile, the improved electrochemical kinetics resulting from B/N co-doping sites and rGO/BNNSs heterostructure, effectively promote Li-ions diffusion and catalyze the redox kinetics of Li 2 S and LiPSs. Encouraged by the synergistic effect, the Li-S battery with B/N co-doping rGO/BNNSs coating shows a reversible capacity of 966.6 mAh g−1 at 1C. Upon increased current density of 4C, a desirable initial discharge capacity of 741.5 mAh g-1can be acquired with ultralow capacity decay of 0.015% per cycle after 500 cycles. Even under high sulfur areal loading configuration, the cell still has remarkable cycling stability. The fundamental explorations on inhibiting LiPSs shuttle and promoting various sulfur species conversion demonstrate the great potential of B/N co-doping rGO/BNNSs in practical Li-S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • The formation mechanism of porous BN foams (BNFs) is studied in-depth. • BNFs exhibit hierarchical pore structures and robust mechanical integrity. • BNFs possess high adsorption capacities for CO 2 , liquid nitrogen and naphthalene. • BNFs are designed as permeation-separation and filtration-adsorption columns. Boron nitride (BN) bulk adsorbents replace their powder ones, which indeed make up for many shortcomings of BN's powders in practical adsorption application and become the most promising BN-based multifunctional adsorption materials. However, the difficulty of synthesis greatly limits their development. Here, we prepare a series of highly porous BN foams (BNFs), via a facile compression forming and controllable high-temperature nitriding method. The BNFs have hierarchical pore characteristics, including abundant micropores (~40 vt.%), and various mesopores and macropores (~60 vt.%), while they possess a robust three-dimensional integrality with maximum compression strength up to ~ 2.2 MPa. These properties make the BNFs kinds of desired bulk adsorbents for application in advanced multifunctional adsorption. Firstly, they can capture various gas molecules, including ultrahigh CO 2 capacities of ~ 3.05 mmol/g (0 °C) and ~ 1.75 mmol/g (25 °C), naphthalene of ~ 155 wt% (80 °C) and 89 wt% (20 °C), and liquid nitrogen quantity of ~6.6-times weight of their own weight. In addition, the BNFs with a well hydrophobic-lipophilic surface exhibit remarkable adsorption for a wide range of organic reagents and oils, up to very high capacity of 600–1830 wt%, and show high-end permeation-separation and filtration-adsorption application in oil–water systems. Moreover, as a kind of static block adsorbents, the BNFs also have outstanding pollutant adsorption performances for S 8 and Li 2 S x in organic solvents, and the Ni(II) ions and methylene blue molecules in water. We believe that our new BNFs materials will be of great significance to lead the BN-based bulk adsorbents for continuous application in more sophisticated fields. [ABSTRACT FROM AUTHOR]

A template-free pyrolysis route has been developed using condensation-assembly precursors made of trimethoxyboroxane (TMB) and melamine (M) to cater the requirements of an industrial real-world environment. The precursors contain abundant B–N bonds and exhibit a high level of interconnectivity, resulting in 3D-PBN with enhanced mechanical properties and the ability to be easily customized in terms of shape. Moreover, 3D-PBN demonstrates rapid adsorption kinetics and excellent reusability, efficiently removing up to 270% of its own weight of fuel within 30 s and being readily regenerated through simple calcination. Even after undergoing 50 cycles, the mechanical properties remain at a remarkable 80%, while the adsorption performance exceed 95%. Furthermore, a comprehensive analysis of thermal behavior from precursor to 3D-PBN has been conducted, leading to the proposal of a molecular-scale evolution process comprising four major steps. This understanding enables us to control the phase reaction and regulate the composition of the products, which is crucial for determining the characteristics of the final product. Three-dimensionally porous boron nitride is prepared by pyrolysis of the preformed condensation-assembly melamine-trimethoxyboroxine precursor, and exhibit an efficient oil clearance capacity. [Display omitted] • Generation of C–N–B–O basic unit interconnected precursors by condensation assembly. • Three-dimensional porous boron nitride (3D-PBN) with excellent overall performance. • Revealing the complete reaction process on a molecular scale. • 3D-PBN maintains high efficiency after 50 cycles of oil removal. [ABSTRACT FROM AUTHOR]