Heterogeneous metal-catalyzed chemical conversions with a recyclable catalyst are very ideal and challenging for sustainable organic synthesis.A new bipyridyl-Mo(IV)-carbon nitride(CN-K/Mo-Bpy)was prepared by supporti...Heterogeneous metal-catalyzed chemical conversions with a recyclable catalyst are very ideal and challenging for sustainable organic synthesis.A new bipyridyl-Mo(IV)-carbon nitride(CN-K/Mo-Bpy)was prepared by supporting molybdenum complex on C_(3)N_(4)-K and characterized by FT-IR,XRD,SEM,XPS and ICP-OES.Heterogeneous CN–Mo-Bpy catalyst can be applied to the direct amination of nitroarenes and arylboronic acid,thus constructing various valuable diarylamines in high to excellent yields with a wide substrate scope and good functional group tolerance.It is worth noting that this heterogeneous catalyst has high chemical stability and can be recycled for at least five times without reducing its activity.展开更多
Lowering the synthesis temperature of boron nitride nanotubes(BNNTs)is crucial for their development.The primary reason for adopting a high temperature is to enable the effective activation of highmelting-point solid ...Lowering the synthesis temperature of boron nitride nanotubes(BNNTs)is crucial for their development.The primary reason for adopting a high temperature is to enable the effective activation of highmelting-point solid boron.In this study,we developed a novel approach for efficiently activating boron by introducing alkali metal compounds into the conventional MgO–B system.This approach can be adopted to form various low-melting-point AM–Mg–B–O growth systems.These growth systems have improved catalytic capability and reactivity even under low-temperature conditions,facilitating the synthesis of BNNTs at temperatures as low as 850℃.In addition,molecular dynamics simulations based on density functional theory theoretically demonstrate that the systems maintain a liquid state at low temperatures and interact with N atoms to form BN chains.These findings offer novel insights into the design of boron activation and are expected to facilitate research on the low-temperature synthesis of BNNTs.展开更多
Recent advancements in thermal conductivity modulating strategies have shown promising enhancements to the thermal management capabilities of two-dimensional materials.In this article,both the iterative Boltzmann tran...Recent advancements in thermal conductivity modulating strategies have shown promising enhancements to the thermal management capabilities of two-dimensional materials.In this article,both the iterative Boltzmann transport equation solution and the two-temperature model were employed to investigate the efficacy of targeted phonon excitation applied to hexagonal boron nitride(hBN).The results indicate significant modifications to hBN's thermal conductivity,achieving increases of up to 30.1%as well as decreases of up to 59.8%.These findings validate the reliability of the strategy,expand its scope of applicability,and establish it as a powerful tool for tailoring thermal properties across a wider range of fields.展开更多
Single-wall carbon nanotubes(SWCNTs)have attracted significant attention as a thermal management material because of their high thermal conductivity and excellent thermal stability.However,decreasing the great thermal...Single-wall carbon nanotubes(SWCNTs)have attracted significant attention as a thermal management material because of their high thermal conductivity and excellent thermal stability.However,decreasing the great thermal contact resistance at the tube-tube junctions of SWCNT assemblies is a prerequisite for its practical applications.We report a strategy to address this issue by welding the junctions of SWC-NTs together and introducing hexagonal boron nitride(h-BN)encapsulating layers to the surface of the SWCNT bundles.By changing the partial pressure of the BN precursor in a two-step atmospheric-pressure chemical vapor deposition process,amorphous BN nanoparticles and crystalline h-BN were deposited to weld and encapsulate the SWCNT network in sequence.The introduction of the BN led to an in-plane thermal conductivity∼3.8 times higher than that of the SWCNT film,as measured by optothermal Ra-man method.Molecular dynamics simulations demonstrate that the BN welding and encapsulating facil-itate thermal transport by reducing thermal resistance at the tube-tube junctions.Our work brings new insights into facilitating the heat transport in low-dimensional nanomaterial assemblies through struc-tural design.展开更多
Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin ...Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin manipulation.This study investigates defect formation in h-BN using focused helium ion beam(He^(+)FIB)irradiation and post-annealing treatments.We demonstrate that helium ion irradiation at doses up to 2×10^(9) ions/μm^(2) does not induce phase transitions or amorphization.Spectroscopic analyses,including differential reflectance spectroscopy(DRS),photoluminescence(PL),and Raman spectroscopy,reveal substantial defect formation and structural modifications.Notably,the irradiation induces a softening of in-plane and interlayer phonon modes,characterized by frequency redshifts of 10.5 cm^(-1) and 3.2 cm^(-1),respectively.While high-temperature thermal annealing mitigates lattice defects and facilitates single-photon emission,the E_(2g) peak width remains 38%broader and the shear mode peak width is 60%broader compared to pre-annealing conditions in the Raman spectra,indicating residual structural degradation.These findings provide insights into defect engineering mechanisms in h-BN,offering guidance for optimizing processing conditions and advancing quantum and optoelectronic device technologies.展开更多
Negatively charged boron vacancy(V_(B)^(-))spin defects are stable in nanoscale hexagonal boron nitride(hBN)flakes,which can be easily integrated into two-dimensional materials and devices to serve as both sensors and...Negatively charged boron vacancy(V_(B)^(-))spin defects are stable in nanoscale hexagonal boron nitride(hBN)flakes,which can be easily integrated into two-dimensional materials and devices to serve as both sensors and protective materials.Ion irradiation is frequently employed to create V_(B)^(-)spin defects in hBN.However,the optimal ion irradiation parameters remain unclear,even though they play a crucial role in determining the depth and density of the defects,which in turn affect sensing sensitivity.In this work,we optimize the carbon ion irradiation parameters for creating V_(B)^(-)spin defects by varying the irradiation dose and the incident angle.For 30 keV carbon ion irradiation,the optimal irradiation dose to create a V_(B)^(-)ensemble is determined to be 4×10^(13)ions/cm^(2),and both continuous and pulsed optically detected magnetic resonance measurements are used to estimate the magnetic sensitivity and spin coherence properties.Moreover,the incident angle of energetic ions is found to influence both the depth and density distributions of the V_(B)^(-)ensemble,a factor that is often overlooked.These results pave the way for improving the performance of quantum sensors based on hBN spin defects by optimizing the irradiation parameters.展开更多
The miniaturization and high-power density of electronic devices presents new challenges in thermal management.The precise control of microstructure arrangement,particularly in boron nitride nanosheets(BNNS),is essent...The miniaturization and high-power density of electronic devices presents new challenges in thermal management.The precise control of microstructure arrangement,particularly in boron nitride nanosheets(BNNS),is essential for achieving efficient heat dissipation in highly thermally conductive composites within electrically insulating package.In this work,manganese ferrite was hydrothermally synthesized on BNNS,creating a layered structure in a magnetically responsive nanohybrid material named BNNS@M.This material was then integrated into a waterborne polyurethane(WPU)solution and shaped under a magnetic field to produce thermally conductive film.By altering the magnetic field direction,the mi-crostructure orientation of BNNS@M was controlled,resulting in anisotropic thermally conductive com-posite films with horizontal and vertical orientations.Specifically,under a vertical magnetic field,the film 30-Ve-BNNS@WPU,containing 30 wt.%BNNS@M,achieved a through-plane thermal conductivity of 8.5 W m^(−1)K^(−1)and an in-plane thermal conductivity of 1.8 W m^(−1)K^(−1),showcasing significant anisotropic thermal conductivity.Meanwhile,these films demonstrated excellent thermal stability,mechanical per-formance,and flame retardancy.Furthermore,employing Foygel’s theory elucidated the impact of filler arrangement on thermal conductivity mechanisms and the actual application of 5 G device chips and LED lamps emphasizing the potential of these thermally conductive films in thermal management appli-cations.This investigation contributes valuable design concepts and foundations for the development of anisotropic thermally conductive composites suitable for electron thermal management.展开更多
Solid electrolytes are the most promising candidate for replacing liquid electrolytes due to their safetyand chemical stability advantages. However, a single inorganic or organic solid electrolyte cannot meetthe requi...Solid electrolytes are the most promising candidate for replacing liquid electrolytes due to their safetyand chemical stability advantages. However, a single inorganic or organic solid electrolyte cannot meetthe requirements of commercial all-solid-state batteries (ASSBs), which motivates the composite polymerelectrolyte (CPE). Herein, a CPE of boron nitride nanofiber (BNNF) with a high specific surface area, richpore structure, and poly (ethylene oxide) (PEO) are reported. Anions strongly adsorb on the surface ofBNNF through electrostatic interactions based on oxygen vacancies, promoting the dissociation of lithiumsalts at the two-phase interface. The three-dimensional (3D) BNNF network provides three advantagesin the CPE, including (i) improving ionic conductivity through strong interaction between polymers andfillers, (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 highionic conduction of 4.21 × 10^(−4) S cm^(−1) at 60 ℃ and excellent cycling stability (plating/stripping cyclesfor 2000 h with a low overpotential of ∼40 mV), which results in excellent electrochemical performanceof LiFePO_(4) (LFP) full cell assembled with CPE-5BNNF-1300 (152.7 mAh g^(−1) after 200 cycles at 0.5 C, and134.8 mAh g^(−1) at 2.0 C). Furthermore, when matched with high-voltage LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2) (NCM622), italso exhibits an outstanding rate capacity of 120.4 mAh g^(−1) at 1.0 C. This work provides insight into theBNNF composite electrolyte and promotes its practical application for ASSBs.展开更多
Polysiloxane-based thermally conductive composites are essential for electronic heat management,but they face challenges such as limited thermal conductivity enhancement and low improvement efficiency.In this work,a n...Polysiloxane-based thermally conductive composites are essential for electronic heat management,but they face challenges such as limited thermal conductivity enhancement and low improvement efficiency.In this work,a novel liquid crystal crosslinker(LCC)based on biphenyl liquid crystal moieties was synthe-sized.Liquid crystal polydimethylsiloxane(LC-PDMS)with intrinsic highλwas prepared by crosslinking vinyl/methyl-hydrogen functionalized PDMS by LCC at its liquid crystal transition temperature,and boron nitride nanosheets(BNNs)with different particle sizes were used to prepare BNNs/LC-PDMS composites.When the mass ratio of LCC to vinyl-terminated PDMS is 2:1,the LC-PDMS exhibitsa well-ordered liquid crystal phase,and itsλ_(Ⅱ)reachesthe maximum value of 0.34 W(m K)^(-1),approximately 1.7 times that of general PDMS(0.20 W(m K)^(-1)).Theλ_(Ⅱ)of BNNs/LC-PDMS composites increases with the addition of BNNs,and when the mass fraction of BNNs reaches 30 wt%,with a 1:9 mass ratio of small BNNs(1μm)to large BNNs(10μm),the composite achieves the highestλ_(Ⅱ)of 12.50 W(m K)^(-1),a 68.5%increase com-pared to BNNs/PMDS composites containing the same amount of BNNs(7.42 W(m K)^(-1)).Additionally,BNNs/LC-PDMS composites also demonstrate excellent electrical insulation properties and low density,making them promising candidates for applications in highly integrated electronics fields.展开更多
The rapid expansion of marine industries has created an urgent demand for advanced engineering materials with superior multifunctional performance.While Cu-Ni alloys demonstrate favorable stability and tribological ch...The rapid expansion of marine industries has created an urgent demand for advanced engineering materials with superior multifunctional performance.While Cu-Ni alloys demonstrate favorable stability and tribological characteristics,their practical applications are constrained by compromised thermal conductivity and insufficient mechanical strength due to the solid solution of a high amount of Ni in the Cu matrix.Cu-Ni matrix composites reinforced with hexagonal boron nitride(h-BN)have garnered significant attention due to their potential for tailored mechanical and thermal properties.However,challenges such as BN agglomerations in Cu-Ni matrix and poor interfacial bonding hinder their practical applications.To address these limitations,this study proposes an innovative fabrication strategy for boron nitride nanosheets(BNNSs)reinforced Cu-Ni composites by integrating the in situ synthesis of BNNSs on Cu powders via chemical vapor deposition with powder metallurgy.Benefited by the in situ strategy,BNNSs with high crystallinity distribute uniformly within the Cu matrix and have an intimate interfacial bonding without voids or other types of defects.Remarkably,the BNNSs/Cu-30%Ni composite achieves simultaneous enhancement in strength and ductility,exhibiting an ultimate tensile strength of 417 MPa and fracture elongation of 17.5%,representing 30%and 118%improvements over pure Cu-Ni alloys,respectively.This exceptional mechanical synergy originates from threefold strengthening mechanisms:grain refinement,mobile dislocation pinning,and efficient stress transfer via robust interfaces.The microstructural analysis confirms that homogenous distribution of BNNSs optimized stress distribution,mitigating strain localization in the composites.Fractographic examination demonstrates uniformly distributed dimples containing embedded BNNSs,indicative of effective crack bridging and deflection during failure.Furthermore,the composite possesses excellent corrosion resistance comparable to matrix alloys,while achieving 21.23%enhancement in thermal conductivity and 20%reduction in coefficient of friction.The scalable fabrication protocol successfully resolves longstanding challenges in BNNSs dispersion and interfacial bonding,offering a viable pathway for designing high-performance CMCs for marine applications.展开更多
The research on materials capable of manipulating thermal conductivity continues to fuel the development of thermal controlling devices.Here,using ab initio calculations and the Boltzmann transport equation,we demonst...The research on materials capable of manipulating thermal conductivity continues to fuel the development of thermal controlling devices.Here,using ab initio calculations and the Boltzmann transport equation,we demonstrate that the thermal conductivity of semi-fluorinated hexagonal boron nitride(h-BN)can be reversibly manipulated at 300 K,and the ratio for the regulation of thermal conductivity reaches up to 11.23.Such behavior originates from the high sensitivity of thermal conductivity to magnetic ordering.Semi-fluorinated h-BN is a paramagnetic material at room temperature due to its Curie temperature of 270 K.Impressively,semi-fluorinated h-BN can be modulated into a ferromagnetic system by adding an external magnetic field of 11.15 T,resulting in greatly and reversibly tunable thermal conductivity at room temperature.Furthermore,in-depth analyses of phonon properties show that compared with the paramagnetic phase,both ferromagnetic and antiferromagnetic semi-fluorinated h-BN significantly reduce phonon scattering and anharmonicity,thereby enhancing thermal conductivity.The results qualify semi-fluorinated h-BN as a potential candidate for thermal switching applications at room temperature.展开更多
Weak water stability and lithium reactivity are two major stability issues of sulfide solid-state electrolytes(SSEs)for all-solid-state lithium metal batteries.Here,we report on nano-sized boron nitride(BN)-coated Li_...Weak water stability and lithium reactivity are two major stability issues of sulfide solid-state electrolytes(SSEs)for all-solid-state lithium metal batteries.Here,we report on nano-sized boron nitride(BN)-coated Li_(5.7)PS_(4.7)Cl_(1.3)(BN@LPSC1.3)sulfide SSE,which exhibits reduced H_(2)S emission and improved ionic conductivity retention after relative humidity 1.2%-1.5%ambient condition exposure.Furthermore,BN can partially react with lithium metal to create stable Li_(3)N,resulting in BN@LPSC1.3 showing reduced reactivity against lithium metal and a higher critical current density of 2.2mA/cm^(2).The Li/BN@LPSC/Li symmetrical battery also shows considerably greater stability for>2000 h at a current density of 0.1mA/cm^(2).Despite the high cathode mass loading of 13.38mg/cm^(2),the LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/BN@LPSC1.3/Li all-solidstate lithium metal battery achieves 84.34%capacity retention even after 500 cycles at 0.1 C and room temperature(25℃).展开更多
Boron nitride containing hydroxyl groups efficiently catalysed oxidative dehydrogenation of ethane to ethylene,offering rather high selectivity（95%） but only small amount of CO2 formation（0.4%） at a given ethane c...Boron nitride containing hydroxyl groups efficiently catalysed oxidative dehydrogenation of ethane to ethylene,offering rather high selectivity（95%） but only small amount of CO2 formation（0.4%） at a given ethane conversion of 11%.Even at high conversion level of 63%,the selectivity of ethylene retained at 80%,which is competitive with the energy-demanding industrialized steam cracking route.A long-term test for 200 h resulted in stable conversion and product selectivity,showing the excellent catalytic stability.Both experimental and computational studies have identified that the hydrogen abstraction of B-OH groups by molecular oxygen dynamically generated the active sites and triggered ethane dehydrogenation.展开更多
Boron nitride(BN) nanostructures with complementary functions to their carbon counterparts are one of the most intriguing nanomaterials.Here we devote a compact review on the syntheses of BN nanomaterials:typical zero...Boron nitride(BN) nanostructures with complementary functions to their carbon counterparts are one of the most intriguing nanomaterials.Here we devote a compact review on the syntheses of BN nanomaterials:typical zero-dimensional(OD) fullerenes and nanoparticles,one-dimensional(1D) nanotubes and nanoribbons,two-dimensional(2D) nanosheets as well as three-dimensional(3D) nanoporous BN.Combining low-dimensional quantum confinement and surface effects with unique physical and chemical properties of BN,e.g.excellent electric insulation,wide band gap,and high chemical and thermal stability,BN nanomaterials have drawn particular attention in a variety of potential applications,e.g.luminescence,functional composites,hydrogen accumulators,and advanced insulators,which are also reviewed.展开更多
The aim of this paper was to study the reaction between a Ti-6Al-4V alloy and boron nitride based investment shell molds used for investment casting titanium. In BN based investment shell molds, the face coatings are ...The aim of this paper was to study the reaction between a Ti-6Al-4V alloy and boron nitride based investment shell molds used for investment casting titanium. In BN based investment shell molds, the face coatings are made of pretreated hexagonal boron nitride （hBN） with a few yttria （Y2O3） and colloidal yttria as binder. The Ti-6Al-4V alloy was melted in a controlled atmosphere induction furnace with a segment water-cooled copper crucible. The cross-section of reaction interface between Ti alloys and shell mold was investigated by electron probe micro-analyzer （EPMA） and microhardness tester. The results show that the reaction is not serious, the thickness of the reacting layer is about 30-50 μm, and the thickness of α-case is about 180-200 pro. Moreover the α-case formation mechanism was also discussed.展开更多
Hexagonal boron nitride(h-BN),with unique structural and properties,has shown enormous potentitoward variety of possible applications.By virtue of partially-ionic character of BN chemical bonds anusually large specifi...Hexagonal boron nitride(h-BN),with unique structural and properties,has shown enormous potentitoward variety of possible applications.By virtue of partially-ionic character of BN chemical bonds anusually large specific surface area,h-BN-related nanostructures exhibit appealing adsorption propertiewhich can be widely applied for separation and purification towards energy and environment treatmenIn this review,recent progress in designing h-BN micro,nano-structure,controlled synthesis,performancoptimizing as well as energy and environment-related adsorption applications are summarized.Strategieto tailor the h-BN can be classified as morphology control,element doping,defect control and surfacmodification,focusing on how to optimize the adsorption performance.In order to insight the intrinsimechanism of tuning strategies for property optimization,the significant adsorption applications of h-Btowards hydrogen storage,CO2 capture,pollutants removal from water and adsorption desulfurization arpresented.展开更多
Oxidative desulfurization(ODS)has been proved to be an efficient strategy for the production of clean fuel oil.Numerous metal-based materials have been employed as excellent ODS catalysts,but being hindered by their h...Oxidative desulfurization(ODS)has been proved to be an efficient strategy for the production of clean fuel oil.Numerous metal-based materials have been employed as excellent ODS catalysts,but being hindered by their high-cost and potential secondary pollution.In this work,we employed graphene analogous hexagonal boron nitride(h-BN)as a metal-free catalyst for ODS with hydrogen peroxide(H2O2)as the oxidant.The h-BN catalyst was characterized and proved to be a few-layered structure with relatively high specific surface areas.The h-BN catalyst showed a 99.4%of sulfur removal in fuel oil under the optimized reaction conditions.Besides,the h-BN can be recycled for 8 times without significant decrease in the catalytic performance.Detailed mechanism analysis found that it is the boron radicals in h-BN activated H2O2 to generate·OH species,which can readily oxidize sulfides to corresponding sulfones for separation.This work would provide another choice in choosing metal-free catalysts for ODS.展开更多
Boron nitride(BN)aerogels,composed of nanoscale BN building units together with plenty of air in between these nanoscale building units,are ultralight ceramic materials with excellent thermal/electrical insulation,gre...Boron nitride(BN)aerogels,composed of nanoscale BN building units together with plenty of air in between these nanoscale building units,are ultralight ceramic materials with excellent thermal/electrical insulation,great chemical stability and high-temperature oxidation resistance,which offer considerable advantages for various applications under extreme conditions.However,previous BN aerogels cannot resist high temperature above 900℃ in air atmosphere,and hightemperature oxidation resistance enhancement for BN aerogels is still a great challenge.Herein,a calcium-doped BN(Ca-BN)aerogel with enhanced high-temperature stability(up to~1300℃ in air)was synthesized by introducing Ca atoms into crystal structure of BN building blocks via high-temperature reaction between calcium phosphate and melamine diborate architecture.Such Ca-BN aerogels could resist the burning of butane flame(~1300℃)and keep their megashape and microstructure very well.Furthermore,Ca-BN aerogel serves as thermal insulation layer,together with Al foil serving as both low-infrared-emission layer and high-infrared-reflection layer,forming a combination structure that can effectively hide high-temperature target(heated by butane flame).Such successful chemical doping of metal element into crystal structure of BN may be helpful in the future design and fabrication of advanced BN aerogel materials,and further extending their possible applications to extremely high-temperature environments.展开更多
Supported-Au catalysts show excellent activity in CO oxidation,where the nature of the support has a significant impact on catalytic activity.In this work,a hexagonal boron nitride(BN)support with a high surface area ...Supported-Au catalysts show excellent activity in CO oxidation,where the nature of the support has a significant impact on catalytic activity.In this work,a hexagonal boron nitride(BN)support with a high surface area and adequately exposed edges was obtained by the ball-milling technique.Thereafter,impregnation of the BN support with Cu(NO3)2 followed by calcination under air at 400℃ yielded a CuO-modified support.After Au loading,the obtained Au-CuO_(x)/BN catalyst exhibited high CO oxidation activity at low temperatures with a 50%CO conversion temperature(T50%)of 25℃ and a complete CO conversion temperature(T100%)of 80℃,well within the operational temperature range of proton exchange membrane fuel cells.However,the CO oxidation activity of Au/BN,prepared without CuO_(x) for comparison,was found to be relatively low.Our study reveals that BN alone disperses both Cu and Au nanoparticles well.However,Au nanoparticles on the surface of BN in the absence of CuO species tend to aggregate upon CO oxidation reactions.Conversely,Au nanoparticles supported on the surface of CuO-modified BN remain small with an average size of~2.0 nm before and after CO oxidation.Moreover,electron transfer between Au and Cu species possibly favors the stabilization of highly dispersed Au nanoparticles on the BN surface and also enhances CO adsorption.Thus,our results demonstrate that thermally stable and conductive CuO-modified BN is an excellent support for the preparation of highly dispersed and stable Au catalysts.展开更多
The amorphous boron nitride ceramic powders were prepared at 750-950 ℃ by the low-cost urea route, and the effects of preparation temperatures, molar ratios of the raw materials and oxidation treatment on the composi...The amorphous boron nitride ceramic powders were prepared at 750-950 ℃ by the low-cost urea route, and the effects of preparation temperatures, molar ratios of the raw materials and oxidation treatment on the composition, structure and surface morphology of the products were investigated through FT-IR, XRD and SEM. The results show that the products ceramize and crystallize gradually with the increase of the temperature. When the molar ratio and reaction temperature are 3：2 and 850 ℃, respectively, the products have high purity, compact structure and nice shape. The oxidation treatment at 450 ℃ will not impair the composition and structure of boron nitride but effectively remove the impurities.展开更多
基金support for this work by Hebei Education Department(No.JZX2024004)Central Guidance on Local Science and Technology Development Fund of Hebei Province(No.236Z1404G)+3 种基金the National Natural Science Foundation of China(Nos.22301060 and 21272053)China Postdoctoral Science Foundation(No.2023M730914)the Natural Science Foundation of Hebei Province(Biopharmaceutical Joint Fund No.B2022206008)Project of Science and Technology Department of Hebei Province(No.22567622H)。
文摘Heterogeneous metal-catalyzed chemical conversions with a recyclable catalyst are very ideal and challenging for sustainable organic synthesis.A new bipyridyl-Mo(IV)-carbon nitride(CN-K/Mo-Bpy)was prepared by supporting molybdenum complex on C_(3)N_(4)-K and characterized by FT-IR,XRD,SEM,XPS and ICP-OES.Heterogeneous CN–Mo-Bpy catalyst can be applied to the direct amination of nitroarenes and arylboronic acid,thus constructing various valuable diarylamines in high to excellent yields with a wide substrate scope and good functional group tolerance.It is worth noting that this heterogeneous catalyst has high chemical stability and can be recycled for at least five times without reducing its activity.
基金supported by the National Natural Science Foundation of China(No.51972162)the Fundamental Research Funds for the Central Universities(No.2024300440).
文摘Lowering the synthesis temperature of boron nitride nanotubes(BNNTs)is crucial for their development.The primary reason for adopting a high temperature is to enable the effective activation of highmelting-point solid boron.In this study,we developed a novel approach for efficiently activating boron by introducing alkali metal compounds into the conventional MgO–B system.This approach can be adopted to form various low-melting-point AM–Mg–B–O growth systems.These growth systems have improved catalytic capability and reactivity even under low-temperature conditions,facilitating the synthesis of BNNTs at temperatures as low as 850℃.In addition,molecular dynamics simulations based on density functional theory theoretically demonstrate that the systems maintain a liquid state at low temperatures and interact with N atoms to form BN chains.These findings offer novel insights into the design of boron activation and are expected to facilitate research on the low-temperature synthesis of BNNTs.
基金supported by the National Key Research and Development Project of China(Grant No.2018YFE0127800)。
文摘Recent advancements in thermal conductivity modulating strategies have shown promising enhancements to the thermal management capabilities of two-dimensional materials.In this article,both the iterative Boltzmann transport equation solution and the two-temperature model were employed to investigate the efficacy of targeted phonon excitation applied to hexagonal boron nitride(hBN).The results indicate significant modifications to hBN's thermal conductivity,achieving increases of up to 30.1%as well as decreases of up to 59.8%.These findings validate the reliability of the strategy,expand its scope of applicability,and establish it as a powerful tool for tailoring thermal properties across a wider range of fields.
基金supported by the National Key R&D Program of China(No.2022YFA1203303)the National Natural Science Foundation of China(Nos.52472054,52130209,and 52072376).
文摘Single-wall carbon nanotubes(SWCNTs)have attracted significant attention as a thermal management material because of their high thermal conductivity and excellent thermal stability.However,decreasing the great thermal contact resistance at the tube-tube junctions of SWCNT assemblies is a prerequisite for its practical applications.We report a strategy to address this issue by welding the junctions of SWC-NTs together and introducing hexagonal boron nitride(h-BN)encapsulating layers to the surface of the SWCNT bundles.By changing the partial pressure of the BN precursor in a two-step atmospheric-pressure chemical vapor deposition process,amorphous BN nanoparticles and crystalline h-BN were deposited to weld and encapsulate the SWCNT network in sequence.The introduction of the BN led to an in-plane thermal conductivity∼3.8 times higher than that of the SWCNT film,as measured by optothermal Ra-man method.Molecular dynamics simulations demonstrate that the BN welding and encapsulating facil-itate thermal transport by reducing thermal resistance at the tube-tube junctions.Our work brings new insights into facilitating the heat transport in low-dimensional nanomaterial assemblies through struc-tural design.
基金supported by the National Natural Science Foundation of China(Grant Nos.11727902,12074372,12174385,12334014,and 12304112).
文摘Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin manipulation.This study investigates defect formation in h-BN using focused helium ion beam(He^(+)FIB)irradiation and post-annealing treatments.We demonstrate that helium ion irradiation at doses up to 2×10^(9) ions/μm^(2) does not induce phase transitions or amorphization.Spectroscopic analyses,including differential reflectance spectroscopy(DRS),photoluminescence(PL),and Raman spectroscopy,reveal substantial defect formation and structural modifications.Notably,the irradiation induces a softening of in-plane and interlayer phonon modes,characterized by frequency redshifts of 10.5 cm^(-1) and 3.2 cm^(-1),respectively.While high-temperature thermal annealing mitigates lattice defects and facilitates single-photon emission,the E_(2g) peak width remains 38%broader and the shear mode peak width is 60%broader compared to pre-annealing conditions in the Raman spectra,indicating residual structural degradation.These findings provide insights into defect engineering mechanisms in h-BN,offering guidance for optimizing processing conditions and advancing quantum and optoelectronic device technologies.
基金supported by the National Key Research and Development Program Project(2024YFF0726104)Key Laboratory of Modern Optical Technologies of the Education Ministry of China,Soochow University(Grant No.KJS2135)+1 种基金a China Postdoctoral Science Foundation Funded Project(Grant No.2024M751236)the Jiangxi Provincial Natural Science Foundation(Grant No.20232BAB211030).
文摘Negatively charged boron vacancy(V_(B)^(-))spin defects are stable in nanoscale hexagonal boron nitride(hBN)flakes,which can be easily integrated into two-dimensional materials and devices to serve as both sensors and protective materials.Ion irradiation is frequently employed to create V_(B)^(-)spin defects in hBN.However,the optimal ion irradiation parameters remain unclear,even though they play a crucial role in determining the depth and density of the defects,which in turn affect sensing sensitivity.In this work,we optimize the carbon ion irradiation parameters for creating V_(B)^(-)spin defects by varying the irradiation dose and the incident angle.For 30 keV carbon ion irradiation,the optimal irradiation dose to create a V_(B)^(-)ensemble is determined to be 4×10^(13)ions/cm^(2),and both continuous and pulsed optically detected magnetic resonance measurements are used to estimate the magnetic sensitivity and spin coherence properties.Moreover,the incident angle of energetic ions is found to influence both the depth and density distributions of the V_(B)^(-)ensemble,a factor that is often overlooked.These results pave the way for improving the performance of quantum sensors based on hBN spin defects by optimizing the irradiation parameters.
基金supported by the National Natural Science Foundation of China(No.22268025)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011985)the Applied Basic Research Program of Yunnan Province(Nos.202201AT070115,202201BE070001–031).
文摘The miniaturization and high-power density of electronic devices presents new challenges in thermal management.The precise control of microstructure arrangement,particularly in boron nitride nanosheets(BNNS),is essential for achieving efficient heat dissipation in highly thermally conductive composites within electrically insulating package.In this work,manganese ferrite was hydrothermally synthesized on BNNS,creating a layered structure in a magnetically responsive nanohybrid material named BNNS@M.This material was then integrated into a waterborne polyurethane(WPU)solution and shaped under a magnetic field to produce thermally conductive film.By altering the magnetic field direction,the mi-crostructure orientation of BNNS@M was controlled,resulting in anisotropic thermally conductive com-posite films with horizontal and vertical orientations.Specifically,under a vertical magnetic field,the film 30-Ve-BNNS@WPU,containing 30 wt.%BNNS@M,achieved a through-plane thermal conductivity of 8.5 W m^(−1)K^(−1)and an in-plane thermal conductivity of 1.8 W m^(−1)K^(−1),showcasing significant anisotropic thermal conductivity.Meanwhile,these films demonstrated excellent thermal stability,mechanical per-formance,and flame retardancy.Furthermore,employing Foygel’s theory elucidated the impact of filler arrangement on thermal conductivity mechanisms and the actual application of 5 G device chips and LED lamps emphasizing the potential of these thermally conductive films in thermal management appli-cations.This investigation contributes valuable design concepts and foundations for the development of anisotropic thermally conductive composites suitable for electron thermal management.
基金financially supported by the Science and Tech-nology Innovation Base Project(No.226Z3606G)the National Natural Science Foundation of China(No.51802073)+3 种基金the Hebei Province Graduate Student Innovation Ability Training Project(No.CXZZBS2023040)the Hebei Province Eighth Batch of“100 People Plan”Project(No.E2018050008)the Natural Science Foundation of Hebei Province(No.E2018202129)Hebei Key Laboratory of Boron Nitride and Nano Materials.
文摘Solid electrolytes are the most promising candidate for replacing liquid electrolytes due to their safetyand chemical stability advantages. However, a single inorganic or organic solid electrolyte cannot meetthe requirements of commercial all-solid-state batteries (ASSBs), which motivates the composite polymerelectrolyte (CPE). Herein, a CPE of boron nitride nanofiber (BNNF) with a high specific surface area, richpore structure, and poly (ethylene oxide) (PEO) are reported. Anions strongly adsorb on the surface ofBNNF through electrostatic interactions based on oxygen vacancies, promoting the dissociation of lithiumsalts at the two-phase interface. The three-dimensional (3D) BNNF network provides three advantagesin the CPE, including (i) improving ionic conductivity through strong interaction between polymers andfillers, (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 highionic conduction of 4.21 × 10^(−4) S cm^(−1) at 60 ℃ and excellent cycling stability (plating/stripping cyclesfor 2000 h with a low overpotential of ∼40 mV), which results in excellent electrochemical performanceof LiFePO_(4) (LFP) full cell assembled with CPE-5BNNF-1300 (152.7 mAh g^(−1) after 200 cycles at 0.5 C, and134.8 mAh g^(−1) at 2.0 C). Furthermore, when matched with high-voltage LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2) (NCM622), italso exhibits an outstanding rate capacity of 120.4 mAh g^(−1) at 1.0 C. This work provides insight into theBNNF composite electrolyte and promotes its practical application for ASSBs.
基金support from the National Nat-ural Science Foundation of China(No.52403114)the Technolog-ical Base Scientific Research Projects(Highly Thermally Conduc-tive Nonmetal Materials)+3 种基金the Innovation Capability Support Pro-gram of Shaanxi(No.2024RS-CXTD-57)the Natural Science Foun-dation of Chongqing(No.2023NSCQ-MSX2547)the Fundamental Research Funds for the Central Universities(No.D5000240077)the Shaanxi Coal Chemical Industry Technology Research In-stitute Co.,Ltd.(No.2023YJY-Y-HZ-XS-NX003).
文摘Polysiloxane-based thermally conductive composites are essential for electronic heat management,but they face challenges such as limited thermal conductivity enhancement and low improvement efficiency.In this work,a novel liquid crystal crosslinker(LCC)based on biphenyl liquid crystal moieties was synthe-sized.Liquid crystal polydimethylsiloxane(LC-PDMS)with intrinsic highλwas prepared by crosslinking vinyl/methyl-hydrogen functionalized PDMS by LCC at its liquid crystal transition temperature,and boron nitride nanosheets(BNNs)with different particle sizes were used to prepare BNNs/LC-PDMS composites.When the mass ratio of LCC to vinyl-terminated PDMS is 2:1,the LC-PDMS exhibitsa well-ordered liquid crystal phase,and itsλ_(Ⅱ)reachesthe maximum value of 0.34 W(m K)^(-1),approximately 1.7 times that of general PDMS(0.20 W(m K)^(-1)).Theλ_(Ⅱ)of BNNs/LC-PDMS composites increases with the addition of BNNs,and when the mass fraction of BNNs reaches 30 wt%,with a 1:9 mass ratio of small BNNs(1μm)to large BNNs(10μm),the composite achieves the highestλ_(Ⅱ)of 12.50 W(m K)^(-1),a 68.5%increase com-pared to BNNs/PMDS composites containing the same amount of BNNs(7.42 W(m K)^(-1)).Additionally,BNNs/LC-PDMS composites also demonstrate excellent electrical insulation properties and low density,making them promising candidates for applications in highly integrated electronics fields.
基金financial support of the National Key R&D Program of China(No.SQ2024YFA1200082)the National Natural Science Foundation of China(No.52371013)the Natural Science Foundation of Tianjin City(No.22JCZDJC00020).
文摘The rapid expansion of marine industries has created an urgent demand for advanced engineering materials with superior multifunctional performance.While Cu-Ni alloys demonstrate favorable stability and tribological characteristics,their practical applications are constrained by compromised thermal conductivity and insufficient mechanical strength due to the solid solution of a high amount of Ni in the Cu matrix.Cu-Ni matrix composites reinforced with hexagonal boron nitride(h-BN)have garnered significant attention due to their potential for tailored mechanical and thermal properties.However,challenges such as BN agglomerations in Cu-Ni matrix and poor interfacial bonding hinder their practical applications.To address these limitations,this study proposes an innovative fabrication strategy for boron nitride nanosheets(BNNSs)reinforced Cu-Ni composites by integrating the in situ synthesis of BNNSs on Cu powders via chemical vapor deposition with powder metallurgy.Benefited by the in situ strategy,BNNSs with high crystallinity distribute uniformly within the Cu matrix and have an intimate interfacial bonding without voids or other types of defects.Remarkably,the BNNSs/Cu-30%Ni composite achieves simultaneous enhancement in strength and ductility,exhibiting an ultimate tensile strength of 417 MPa and fracture elongation of 17.5%,representing 30%and 118%improvements over pure Cu-Ni alloys,respectively.This exceptional mechanical synergy originates from threefold strengthening mechanisms:grain refinement,mobile dislocation pinning,and efficient stress transfer via robust interfaces.The microstructural analysis confirms that homogenous distribution of BNNSs optimized stress distribution,mitigating strain localization in the composites.Fractographic examination demonstrates uniformly distributed dimples containing embedded BNNSs,indicative of effective crack bridging and deflection during failure.Furthermore,the composite possesses excellent corrosion resistance comparable to matrix alloys,while achieving 21.23%enhancement in thermal conductivity and 20%reduction in coefficient of friction.The scalable fabrication protocol successfully resolves longstanding challenges in BNNSs dispersion and interfacial bonding,offering a viable pathway for designing high-performance CMCs for marine applications.
基金supported by the Postdoctoral Fellowship Program(Grade C)China Postdoctoral Science Foundation(Grant No.GZC20241421)the Sichuan Science and Technology Program(Grant No.2025ZNSFSC0864)the Fundamental Re search Funds for the Central Universities(Grant No.2682025CX029).
文摘The research on materials capable of manipulating thermal conductivity continues to fuel the development of thermal controlling devices.Here,using ab initio calculations and the Boltzmann transport equation,we demonstrate that the thermal conductivity of semi-fluorinated hexagonal boron nitride(h-BN)can be reversibly manipulated at 300 K,and the ratio for the regulation of thermal conductivity reaches up to 11.23.Such behavior originates from the high sensitivity of thermal conductivity to magnetic ordering.Semi-fluorinated h-BN is a paramagnetic material at room temperature due to its Curie temperature of 270 K.Impressively,semi-fluorinated h-BN can be modulated into a ferromagnetic system by adding an external magnetic field of 11.15 T,resulting in greatly and reversibly tunable thermal conductivity at room temperature.Furthermore,in-depth analyses of phonon properties show that compared with the paramagnetic phase,both ferromagnetic and antiferromagnetic semi-fluorinated h-BN significantly reduce phonon scattering and anharmonicity,thereby enhancing thermal conductivity.The results qualify semi-fluorinated h-BN as a potential candidate for thermal switching applications at room temperature.
基金financial support from the Science and Technology Project of Shenzhen(Nos.JCYJ20210324094206019 and JCYJ20210324094000001).
文摘Weak water stability and lithium reactivity are two major stability issues of sulfide solid-state electrolytes(SSEs)for all-solid-state lithium metal batteries.Here,we report on nano-sized boron nitride(BN)-coated Li_(5.7)PS_(4.7)Cl_(1.3)(BN@LPSC1.3)sulfide SSE,which exhibits reduced H_(2)S emission and improved ionic conductivity retention after relative humidity 1.2%-1.5%ambient condition exposure.Furthermore,BN can partially react with lithium metal to create stable Li_(3)N,resulting in BN@LPSC1.3 showing reduced reactivity against lithium metal and a higher critical current density of 2.2mA/cm^(2).The Li/BN@LPSC/Li symmetrical battery also shows considerably greater stability for>2000 h at a current density of 0.1mA/cm^(2).Despite the high cathode mass loading of 13.38mg/cm^(2),the LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/BN@LPSC1.3/Li all-solidstate lithium metal battery achieves 84.34%capacity retention even after 500 cycles at 0.1 C and room temperature(25℃).
基金supported by the National Natural Science Foundation of China (21225312, U1462120, 21473206)Cheung Kong Scholars Programme of China (T2015036)~~
文摘Boron nitride containing hydroxyl groups efficiently catalysed oxidative dehydrogenation of ethane to ethylene,offering rather high selectivity（95%） but only small amount of CO2 formation（0.4%） at a given ethane conversion of 11%.Even at high conversion level of 63%,the selectivity of ethylene retained at 80%,which is competitive with the energy-demanding industrialized steam cracking route.A long-term test for 200 h resulted in stable conversion and product selectivity,showing the excellent catalytic stability.Both experimental and computational studies have identified that the hydrogen abstraction of B-OH groups by molecular oxygen dynamically generated the active sites and triggered ethane dehydrogenation.
基金financial support of International Center for Young Scientists(ICYS)World Premier International Center for Materials Nanoarchitectonics(WPI-MANA) in National Institute for Materials Science(NIMS)financial support from KAKENHI project(Grant-in-Aid for Young Scientists,26820322) of Japan Society for the Promotion of Science(JSPS)
文摘Boron nitride(BN) nanostructures with complementary functions to their carbon counterparts are one of the most intriguing nanomaterials.Here we devote a compact review on the syntheses of BN nanomaterials:typical zero-dimensional(OD) fullerenes and nanoparticles,one-dimensional(1D) nanotubes and nanoribbons,two-dimensional(2D) nanosheets as well as three-dimensional(3D) nanoporous BN.Combining low-dimensional quantum confinement and surface effects with unique physical and chemical properties of BN,e.g.excellent electric insulation,wide band gap,and high chemical and thermal stability,BN nanomaterials have drawn particular attention in a variety of potential applications,e.g.luminescence,functional composites,hydrogen accumulators,and advanced insulators,which are also reviewed.
文摘The aim of this paper was to study the reaction between a Ti-6Al-4V alloy and boron nitride based investment shell molds used for investment casting titanium. In BN based investment shell molds, the face coatings are made of pretreated hexagonal boron nitride （hBN） with a few yttria （Y2O3） and colloidal yttria as binder. The Ti-6Al-4V alloy was melted in a controlled atmosphere induction furnace with a segment water-cooled copper crucible. The cross-section of reaction interface between Ti alloys and shell mold was investigated by electron probe micro-analyzer （EPMA） and microhardness tester. The results show that the reaction is not serious, the thickness of the reacting layer is about 30-50 μm, and the thickness of α-case is about 180-200 pro. Moreover the α-case formation mechanism was also discussed.
基金financially supported by the National Natural Science Foundation of China (Nos. 21606113, 21676128, and 21722604)the International Postdoctoral Exchange Fellowship by China Postdoctoral Science Foundation (No. 20170055)
文摘Hexagonal boron nitride(h-BN),with unique structural and properties,has shown enormous potentitoward variety of possible applications.By virtue of partially-ionic character of BN chemical bonds anusually large specific surface area,h-BN-related nanostructures exhibit appealing adsorption propertiewhich can be widely applied for separation and purification towards energy and environment treatmenIn this review,recent progress in designing h-BN micro,nano-structure,controlled synthesis,performancoptimizing as well as energy and environment-related adsorption applications are summarized.Strategieto tailor the h-BN can be classified as morphology control,element doping,defect control and surfacmodification,focusing on how to optimize the adsorption performance.In order to insight the intrinsimechanism of tuning strategies for property optimization,the significant adsorption applications of h-Btowards hydrogen storage,CO2 capture,pollutants removal from water and adsorption desulfurization arpresented.
基金All authors appreciate the financial support from the National Key R&D Program of China(2017YFB0306504)the National Natural Science Foundation of China(No.21722604,21878133 and 21908082)+2 种基金China Postdoctoral Science Foundation(No.2019M651743)Natural Science Foundation of Jiangsu Province(BK20190852,BK20190854)Natural Science Foundation for Jiangsu Colleges and Universities(19KJB530005).
文摘Oxidative desulfurization(ODS)has been proved to be an efficient strategy for the production of clean fuel oil.Numerous metal-based materials have been employed as excellent ODS catalysts,but being hindered by their high-cost and potential secondary pollution.In this work,we employed graphene analogous hexagonal boron nitride(h-BN)as a metal-free catalyst for ODS with hydrogen peroxide(H2O2)as the oxidant.The h-BN catalyst was characterized and proved to be a few-layered structure with relatively high specific surface areas.The h-BN catalyst showed a 99.4%of sulfur removal in fuel oil under the optimized reaction conditions.Besides,the h-BN can be recycled for 8 times without significant decrease in the catalytic performance.Detailed mechanism analysis found that it is the boron radicals in h-BN activated H2O2 to generate·OH species,which can readily oxidize sulfides to corresponding sulfones for separation.This work would provide another choice in choosing metal-free catalysts for ODS.
基金financially supported by the Royal Society Newton Advanced Fellowship(NA170184)the National Natural Science Foundation of China(52173052)the Natural Science Foundation of Jiangsu Province(BK20210133).
文摘Boron nitride(BN)aerogels,composed of nanoscale BN building units together with plenty of air in between these nanoscale building units,are ultralight ceramic materials with excellent thermal/electrical insulation,great chemical stability and high-temperature oxidation resistance,which offer considerable advantages for various applications under extreme conditions.However,previous BN aerogels cannot resist high temperature above 900℃ in air atmosphere,and hightemperature oxidation resistance enhancement for BN aerogels is still a great challenge.Herein,a calcium-doped BN(Ca-BN)aerogel with enhanced high-temperature stability(up to~1300℃ in air)was synthesized by introducing Ca atoms into crystal structure of BN building blocks via high-temperature reaction between calcium phosphate and melamine diborate architecture.Such Ca-BN aerogels could resist the burning of butane flame(~1300℃)and keep their megashape and microstructure very well.Furthermore,Ca-BN aerogel serves as thermal insulation layer,together with Al foil serving as both low-infrared-emission layer and high-infrared-reflection layer,forming a combination structure that can effectively hide high-temperature target(heated by butane flame).Such successful chemical doping of metal element into crystal structure of BN may be helpful in the future design and fabrication of advanced BN aerogel materials,and further extending their possible applications to extremely high-temperature environments.
文摘Supported-Au catalysts show excellent activity in CO oxidation,where the nature of the support has a significant impact on catalytic activity.In this work,a hexagonal boron nitride(BN)support with a high surface area and adequately exposed edges was obtained by the ball-milling technique.Thereafter,impregnation of the BN support with Cu(NO3)2 followed by calcination under air at 400℃ yielded a CuO-modified support.After Au loading,the obtained Au-CuO_(x)/BN catalyst exhibited high CO oxidation activity at low temperatures with a 50%CO conversion temperature(T50%)of 25℃ and a complete CO conversion temperature(T100%)of 80℃,well within the operational temperature range of proton exchange membrane fuel cells.However,the CO oxidation activity of Au/BN,prepared without CuO_(x) for comparison,was found to be relatively low.Our study reveals that BN alone disperses both Cu and Au nanoparticles well.However,Au nanoparticles on the surface of BN in the absence of CuO species tend to aggregate upon CO oxidation reactions.Conversely,Au nanoparticles supported on the surface of CuO-modified BN remain small with an average size of~2.0 nm before and after CO oxidation.Moreover,electron transfer between Au and Cu species possibly favors the stabilization of highly dispersed Au nanoparticles on the BN surface and also enhances CO adsorption.Thus,our results demonstrate that thermally stable and conductive CuO-modified BN is an excellent support for the preparation of highly dispersed and stable Au catalysts.
基金Funded by the National Natural Science Foundation of China (Nos.50902150 & 90916019)the Graduate Innovation Foundation of the National University of Defense Technology(No.S100103)
文摘The amorphous boron nitride ceramic powders were prepared at 750-950 ℃ by the low-cost urea route, and the effects of preparation temperatures, molar ratios of the raw materials and oxidation treatment on the composition, structure and surface morphology of the products were investigated through FT-IR, XRD and SEM. The results show that the products ceramize and crystallize gradually with the increase of the temperature. When the molar ratio and reaction temperature are 3：2 and 850 ℃, respectively, the products have high purity, compact structure and nice shape. The oxidation treatment at 450 ℃ will not impair the composition and structure of boron nitride but effectively remove the impurities.
