Mn-based layered oxides(KMO)have emerged as one of the promising low-cost cathodes for potassiumion batteries(PIBs).However,due to the multiple-phase transitions and the distortion in the MnO6structure induced by the ...Mn-based layered oxides(KMO)have emerged as one of the promising low-cost cathodes for potassiumion batteries(PIBs).However,due to the multiple-phase transitions and the distortion in the MnO6structure induced by the Jahn-Teller(JT)effect associated with Mn-ion,the cathode exhibits poor structural stability.Herein,we propose a strategy to enhance structural stability by introducing robust metal-oxygen(M-O)bonds,which can realize the pinning effect to constrain the distortion in the transition metal(TM)layer.Concurrently,all the elements employed have exceptionally high crustal abundance.As a proof of concept,the designed K_(0.5)Mn_(0.9)Mg_(0.025)Ti_(0.025)Al_(0.05)O_(2)cathode exhibited a discharge capacity of approximately 100 mA h g^(-1)at 20 mA g^(-1)with 79%capacity retention over 50 cycles,and 73%capacity retention over 200 cycles at 200 mA g^(-1),showcased much better battery performance than the designed cathode with less robust M-O bonds.The properties of the formed M-O bonds were investigated using theoretical calculations.The enhanced dynamics,mitigated JT effect,and improved structural stability were elucidated through the in-situ X-ray diffractometer(XRD),in-situ electrochemical impedance spectroscopy(EIS)(and distribution of relaxation times(DRT)method),and ex-situ X-ray absorption fine structure(XAFS)tests.This study holds substantial reference value for the future design of costeffective Mn-based layered cathodes for PIBs.展开更多
Organofluorines play a crucial role in medicine,agrochemicals,and materials science.Adding fluorine to molecules creates structures with specific beneficial properties or tunes properties through interactions with the...Organofluorines play a crucial role in medicine,agrochemicals,and materials science.Adding fluorine to molecules creates structures with specific beneficial properties or tunes properties through interactions with their environment.Many popular pharmaceuticals and agrochemicals contain fluorine because it enhances hydrogen bonding at protein’s active sites.展开更多
1 As autumn becomes winter,I eagerly anticipate December's reunion with my older brother,Don,at SilverStar Mountain Resort.Our annual“SilverStar time”has reconnected us over the past decade,filling me with excit...1 As autumn becomes winter,I eagerly anticipate December's reunion with my older brother,Don,at SilverStar Mountain Resort.Our annual“SilverStar time”has reconnected us over the past decade,filling me with excitement and reflection.展开更多
The advancement of functional adhesives featuring recyclable and repairable properties is of great significance in interfacial science and engineering.Herein,a series of high-strength,recyclable fluorine-containing ad...The advancement of functional adhesives featuring recyclable and repairable properties is of great significance in interfacial science and engineering.Herein,a series of high-strength,recyclable fluorine-containing adhesives(ESOx-FPF)were designed and synthesized by crosslinking two prepolymers,FPF-B(derived from side-chain fluorinated diol,isocyanate,and aminoboric acid)and ESO-B(synthesized from biobased epoxy soybean oil and aminoboric acid),through dynamic boro-oxygen bonds.The resulting adhesive exhibited an optimal tensile strength of 42 MPa and the shear strength on steel plates reached as high as 3.89 MPa.More importantly,benefiting from the dynamic reversibility of the boron-oxygen bonds along with the hydrogen bonds interaction,ESOx-FPF can be welded with the assistance of solvents and recycled for multiple cycles.The outstanding healing efficiency and excellent reprocessability of these functional adhesives were confirmed by mechanical testing.Moreover,the as-prepared adhesives demonstrated universal and remarkable adhesion to various substrates,such as aromatic polyamide,aluminum plates and polycarbonate,meanwhile,they could be easily disassembled and recycled using ethanol without damaging the substrates surface.This study not only provides a simple strategy for the synthesis of eco-friendly adhesives with weldable and recyclable properties,but also sheds light on the development of other functional materials utilizing dynamic covalent chemistry.展开更多
Low-cost and large-area uniform amorphous Ga_(2)O_(3)(α-Ga_(2)O_(3))solar-blind ultraviolet(UV)detectors have garnered significant attention in recent years.Oxygen vacancy(VO)defects are generally considered as the p...Low-cost and large-area uniform amorphous Ga_(2)O_(3)(α-Ga_(2)O_(3))solar-blind ultraviolet(UV)detectors have garnered significant attention in recent years.Oxygen vacancy(VO)defects are generally considered as the predominant defects affecting the detector performance.Reducing VOconcentration generally results in both low dark current and low photo current,significantly limiting further improvement of the photo-to-dark current ratio(PDCR)parameter.Herein,a delicately optimized atomic layer deposition(ALD)method is revealed having the capability to break through the trade-off in a-Ga_(2)O_(3),achieving both low dark current and high photocurrent simultaneously.For a clear demonstration,a-Ga_(2)O_(3)contrast sample is prepared by magnetron sputtering and compared as well.Combined tests are performed including xray photoelectron spectroscopy,photoluminescence,electron paramagnetic resonance and Fourier-transform infrared spectroscopy.It is found that ALDα-Ga_(2)O_(3)has a lower VOconcentration,but also a lower dangling bonds concentration which are strong non-irradiation recombination centers.Therefore,decrease of dangling bonds is suggested to compensate for the low optical gain induced by low VOconcentration and promote the PDCR to~2.06×10^(6).Our findings firstly prove that the dangling bonds also play an important role in determining the a-Ga_(2)O_(3)detection performance,offering new insights for further promotion ofα-Ga_(2)O_(3)UV detector performance via dual optimization of dangling bonds and VO.展开更多
With the support of the Belt and Road Initiative(BRI),the international reach of traditional Chinese medicine(TCM)is taking shape as a“Silk Road of Health,”opening new pathways for closer connections among peoples.T...With the support of the Belt and Road Initiative(BRI),the international reach of traditional Chinese medicine(TCM)is taking shape as a“Silk Road of Health,”opening new pathways for closer connections among peoples.The journey of TCM,in turn.展开更多
The activation of the N≡N triple bond in N_(2) is a fascinating topic in nitrogen chemistry.The transition metals have been demonstrated to effectively modulate the reactivity of N_(2) molecules under high pressure,l...The activation of the N≡N triple bond in N_(2) is a fascinating topic in nitrogen chemistry.The transition metals have been demonstrated to effectively modulate the reactivity of N_(2) molecules under high pressure,leading to nitrogen-rich compounds.However,their use often results in a significant reduction in energy density.In this work,we propose a series of low-enthalpy nitrogen-rich phases in CN_(x)(x=3,...,7)compounds using a first-principles crystal structure search method.The results of calculations reveal that all these CN compounds are assembled from both CN_(4) tetrahedra and N_(x)(x=1,2,or 5)species.Strikingly,we find that the CN_(4) tetrahedron can effectively activate the N≡N bond through weakening of the π orbital of N_(2) under a pressure of 40 GPa,leading to stable CN polynitrides.The robust structural framework of CN polynitrides containing C-N and N-N bonds plays a crucial role in enhancing their structural stability,energy density,and hardness.Among these polynitrides,CN_(6) possesses not only a very high mass density of 3.19 g/cm^(3),but also an ultrahigh energy density of 28.94 kJ/cm^(3),which represents a significant advance in the development of energetic materials using high-pressure methods.This work provides new insights into the mechanism of N_(2) activation under high pressure,and offers a promising pathway to realize high-performance energetic materials.展开更多
Green bonds, as one of the core tools of green finance, have rapidly developed into a large-scale and far-reaching financial market since the first green bond was issued in 2007. As a direct financing channel for gree...Green bonds, as one of the core tools of green finance, have rapidly developed into a large-scale and far-reaching financial market since the first green bond was issued in 2007. As a direct financing channel for green projects, green bonds have promoted the rapid development of green finance in China, and under the background of “dual carbon”, the demand for green bonds in China has increased significantly. In fact, the Chinese green bond investment market has vast development space. However, due to its late start and immature development, there are doubts about whether green bonds can play a positive role in enhancing the company’s value. Therefore, it is urgent to conduct in-depth analysis of the impact of the company’s issuance of green bonds on its value. In this paper, we used Tobin’s Q to measure company value, and used panel data to explore the impact of issuing green bonds on company value through propensity score matching method. It explored the significant improvement effect of issuing green bonds and increasing their intensity on company value;and then, by analyzing the mediating effect on the impact mechanism of company value, efforts are made to discover that green bonds can enhance company value by alleviating financing constraints and improving information transparency. Finally, based on the conclusions drawn, reasonable suggestions are proposed, which have practical reference value for the development of the green bond market and the construction of a green financial system.展开更多
Constructing multi-dimensional hydrogen bond(H-bond)regulated single-molecule systems with multiemission remains a challenge.Herein,we report the design of a new excited-state intramolecular proton transfer(ESIPT)feat...Constructing multi-dimensional hydrogen bond(H-bond)regulated single-molecule systems with multiemission remains a challenge.Herein,we report the design of a new excited-state intramolecular proton transfer(ESIPT)featured chromophore(HBT-DPI)that shows flexible emission tunability via the multidimensional regulation of intra-and intermolecular H-bonds.The feature of switchable intramolecular Hbonds is induced via incorporating several hydrogen bond acceptors and donors into one single HBT-DPI molecule,allowing the“turn on/off”of ESIPT process by forming isomers with distinct intramolecular Hbonds configurations.In response to different external H-bonding environments,the obtained four types of crystal/cocrystals vary in the contents of isomers and the molecular packing modes,which are mainly guided by the intermolecular H-bonds,exhibiting non-emissive features or emissions ranging from green to orange.Utilizing the feature of intermolecular H-bond guided molecular packing,we demonstrate the utility of this fluorescent material for visualizing hydrophobic/hydrophilic areas on large-scale heterogeneous surfaces of modified poly(1,1-difluoroethylene)(PVDF)membranes and quantitatively estimating the surface hydrophobicity,providing a new approach for hydrophobicity/hydrophilicity monitoring and measurement.Overall,this study represents a new design strategy for constructing multi-dimensional hydrogen bond regulated ESIPT-based fluorescent materials that enable multiple emissions and unique applications.展开更多
Launched in December 2021,the China-Laos Railway(CLR)has created ample opportunities for the development of Laos’crop production,food processing,and manufacturing.A powerful booster to infrastructure connectivity and...Launched in December 2021,the China-Laos Railway(CLR)has created ample opportunities for the development of Laos’crop production,food processing,and manufacturing.A powerful booster to infrastructure connectivity and trade relations between the two countries,the rail project has also opened a door for young people in Laos through vocational training and education cooperation,strengthening the bonds of friendship between the two peoples.展开更多
The intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates(H_(ad))to form strong S-H_(ad) bonds,resu...The intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates(H_(ad))to form strong S-H_(ad) bonds,resulting in a low photocatalytic H_(2) evolution activity.Herein,a cobalt-induced asymmetric electronic distribution is justified as an effective strategy to optimize the electronic configuration of catalytic S sites in NiCoS cocatalysts for highly active photocatalytic H_(2) evolution.To this end,Co atoms are uniformly incorporated in NiS nanoparticles to fabricate homogeneous NiCoS cocatalyst on TiO_(2) surface by a facile photosynthesis strategy.It is revealed that the incorporated Co atoms break the electron distribution symmetry in NiS,thus essentially increasing the electron density of S atoms to form active electron-enriched S^(2+δ)–sites.The electron-enriched S^(2+δ)–sites could interact with Had via an increased antibonding orbital occupancy,which weakens S–Had bonds for efficient H_(ad) adsorption and desorption,endowing the NiCoS cocatalysts with a highly active H_(2) evolution process.Consequently,the optimized NiCoS/TiO_(2)(1:2)photocatalyst displays the highest H_(2) production performance,outperforming the NiS/TiO_(2) and CoS/TiO_(2) samples by factors of 2.1 and 2.5,respectively.This work provides novel insights on breaking electron distribution symmetry to optimize catalytic efficiency of active sites.展开更多
The efficient conversion of lignin into mono-cycloalkanes via both C–O and C–C bonds cleavage are attractive,but challenging due to the high C–C bond dissociation energy.Previous studies have demonstrated that NbO_...The efficient conversion of lignin into mono-cycloalkanes via both C–O and C–C bonds cleavage are attractive,but challenging due to the high C–C bond dissociation energy.Previous studies have demonstrated that NbO_(x)-based catalysts exhibited exceptional capabilities for C_(Ar)–C bond cleavage and broken the limitation of lignin monomers.In this work,we presented an economical multifunctional Pt-Nb/MOR catalyst that achieved an impressive monomer yield of 147%during the depolymerization and hydrodeoxygenation of lignin into mono-cycloalkanes.Reaction pathway studies showed that unlike traditional NbO_(x)-based catalytic system,bicyclohexane was an important intermediate in this system and followed the C_(sp3)–C_(sp3)cleavage pathway after complete cyclic-hydrogenation.Deep investigations demonstrated that the doping of Nb in Pt/MOR not only enhanced the activation of hydrogen by Pt,but also increased the acidity of MOR,both of these are favor for the hydrogenolytic cleavage of C_(sp3)–C_(sp3)bonds.This work provides a low-cost catalyst to obtain high-yield monomers from lignin under relatively mild conditions and would help to design catalysts with higher activity for the valorization of lignin.展开更多
A novel photocatalytic cocatalyst, MoC quantum dots integrated into N-doped carbon microflowers (MoC–NC), was synthesized, establishing a key Mo–N interfacial bond. The Mo–N bond's regulation was achieved by ad...A novel photocatalytic cocatalyst, MoC quantum dots integrated into N-doped carbon microflowers (MoC–NC), was synthesized, establishing a key Mo–N interfacial bond. The Mo–N bond's regulation was achieved by adjusting the pH of Mo-polydopamine precursor solutions. A composite photocatalyst, MoC–NC/CdS (MNS), was formed by in situ growth of nano-CdS on MoC–NC. The pH during synthesis, crucial for Mo–N bond formation, significantly influenced Cr(Ⅵ) reduction and H_(2) evolution performance. The optimal MNS, created at pH 9.0, demonstrated 99.2% reduction efficiency for Cr(Ⅵ) in 20 min and H_(2) evolution rate of 11.4 mmol g^(-1) h^(-1) over 3 h, outperforming Pt/CdS. Mechanistic studies and density functional theory revealed MoC–NC's role in enhancing light absorption, reaction kinetics, and electron transport, attributing to its ultra-small quantum dots and abundant Mo–N bonds.展开更多
Transition-metal-catalyzed cross-electrophile coupling has emerged as a reliable method for constructing carbon–carbon bonds.Herein,we report a general method,cobalt-catalyzed reductive alkynylation,to construct C(sp...Transition-metal-catalyzed cross-electrophile coupling has emerged as a reliable method for constructing carbon–carbon bonds.Herein,we report a general method,cobalt-catalyzed reductive alkynylation,to construct C(sp)-C(sp^(3))and C(sp)-C(sp^(2))bonds.This presented reaction has a broad substrate scope,enabling the efficient cross-electrophile coupling between alkynyl bromides with alkyl halides and aryl or alkenyl(pseudo)halides.This presented reaction is conducted under mild conditions,tolerating many functional groups,thus suitable for the modification and synthesis of biologically active molecules.展开更多
To simultaneously endow thermal conductivity,high glass transition temperature(Tg)and healing capability to glass fiber/epoxy(GFREP)composite,dynamic crosslinked epoxy resin bearing reversibleβ-hydroxyl ester bonds w...To simultaneously endow thermal conductivity,high glass transition temperature(Tg)and healing capability to glass fiber/epoxy(GFREP)composite,dynamic crosslinked epoxy resin bearing reversibleβ-hydroxyl ester bonds was reinforced with boron nitride nanosheets modified glass fiber cloth(GFC@BNNSs).The in-plane heat conduction paths were constructed by electrostatic self-assembly of polyacrylic acid treated GFC and polyethyleneimine decorated BNNSs.Then,the GFC@BNNSs were impregnated with the mixture of lower concentration(3-glycidyloxypropyl)trimethoxysilane grafted BN micron sheets,3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and hexahydro-4-methylphthalic anhydride,which accounted for establishing the through-plane heat transport pathways and avoiding serious deterioration of mechanical performances.The resultant GFREP composite containing less boron nitride particles(17.6 wt%)exhibited superior in-plane(3.29 W·m^(-1)·K^(-1))and through-plane(1.16 W·m^(-1)·K^(-1))thermal conductivities,as well as high Tg of 204℃(Tg of the unfilled epoxy=177℃).The reversible transesterification reaction enabled closure of interlaminar cracks within the composite,achieving decent healing efficiencies estimated by means of tensile strength(71.2%),electrical breakdown strength(83.6%)and thermal conductivity(69.1%).The present work overcame the disadvantages of conventional thermally conductive composites,and provided an efficient approach to prolong the life span of thermally conductive GFREP laminate for high-temperature resistant integrated circuit application.展开更多
Lithium-sulfur batteries(LSBs)are considered promising candidates for next-generation battery technologies owing to their outstanding theoretical energy density and cost-effectiveness.However,the low conductivity and ...Lithium-sulfur batteries(LSBs)are considered promising candidates for next-generation battery technologies owing to their outstanding theoretical energy density and cost-effectiveness.However,the low conductivity and polysulfide shuttling effect of S cathodes severely hamper the practical performance of LSBs.Herein,in situ-generated single layer MXene nanosheet/hierarchical porous carbonized wood fiber(MX/PCWF)composites are prepared via a nonhazardous eutectic activation strategy coupled with pyrolysis-induced gas diffusion.The unique architecture,wherein single layer MXene nanosheets are constructed on carbonized wood fiber walls,ensures rapid polysulfide conversion and continuous electron transfer for redox reactions.The C-Ti-C bonds formed between MXene and PCWF can considerably expedite the conversion of polysulfides,effectively suppressing the shuttle effect.An impressive capacity of 1301.1 m A h g^(-1)at 0.5 C accompanied by remarkable stability is attained with the MX/PCWF host,as evidenced by the capacity maintenance of 722.6 m A h g^(-1)after 500 cycles.Notably,the MX/PCWF/S cathode can still deliver a high capacity of 886.8 m A h g^(-1)at a high S loading of 5.6 mg cm^(-2).The construction of two-dimensional MXenes on natural wood fiber walls offers a competitive edge over S-based cathode materials and demonstrates a novel strategy for developing high-performance batteries.展开更多
In the petrochemical industry process, the relative volatility between the components to be separated is close to one or the azeotrope that systems are difficult to separate. Liquid-liquid extraction is a common and e...In the petrochemical industry process, the relative volatility between the components to be separated is close to one or the azeotrope that systems are difficult to separate. Liquid-liquid extraction is a common and effective separation method, and selecting an extraction agent is the key to extraction technology research. In this paper, a design method of extractants based on elements and chemical bonds was proposed. A knowledge-based molecular design method was adopted to pre-select elements and chemical bond groups. The molecules were automatically synthesized according to specific combination rules to avoid the problem of “combination explosion” of molecules. The target properties of the extractant were set, and the extractant meeting the requirements was selected by predicting the correlation physical properties of the generated molecules. Based on the separation performance of the extractant in liquid-liquid extraction and the relative importance of each index, the fuzzy comprehensive evaluation membership function was established, the analytic hierarchy process determined the mass ratio of each index, and the consistency test results were passed. The results of case study based on quantum chemical analysis demonstrated that effective determination of extractants for the analysis of benzene-cyclohexane systems. The results unanimously prove that the method has important theoretical significance and application value.展开更多
Poly(butylene succinate)(PBS)exhibits many advantages,such as renewability,biodegradability,and impressive thermal and mechanical properties,but is limited by the low melt viscosity and strength resulted from the line...Poly(butylene succinate)(PBS)exhibits many advantages,such as renewability,biodegradability,and impressive thermal and mechanical properties,but is limited by the low melt viscosity and strength resulted from the linear structure.To address this,vitrimeric network was introduced to synthesize PBS vitrimers(PBSVs)based on dynamic imine bonds through melt polymerization of hydroxyl-terminated PBS with vanillin derived imine containing compound and hexamethylene diisocyanate using trimethylolpropane as a crosslinking monomer.PBSVs with different crosslinking degrees were synthesized through changing the content of the crosslinking monomer.The effect of crosslinking degree on the thermal,theological,mechanical properties,and stress relaxation behavior of the PBSVs was studied in detail.The results demonstrated that the melt viscosity,melt strength,and heat resistance were enhanced substantially without obvious depression in crystallizability,thermal stability,and mechanical properties through increasing crosslinking degree.In addition,the PBSVs exhibit thermal reprocessability with mechanical properties recovered by more than 90%even after processing for three times.Furthermore,PBSV with improved melt properties shows significantly improved foamability compared to commercial PBS.This research contributes to the advancement of polymer technology by successfully developing PBS vitrimers with improved properties,showcasing their potential applications in sustainable and biodegradable materials.展开更多
An efficient and scalable electrochemical asymmetric protocol with metal-free catalysts and even without additional oxidants for the cross-dehydrogenative coupling reaction(CDC)of two C(sp^(3))-H bonds is reported.A s...An efficient and scalable electrochemical asymmetric protocol with metal-free catalysts and even without additional oxidants for the cross-dehydrogenative coupling reaction(CDC)of two C(sp^(3))-H bonds is reported.A series of aldehydes including natural products and various substrates containing C(sp^(3))-H bonds including xanthenes,acridines,cycloheptatrienes and even diarylmethane have been shown to undergo asymmetric CDC to afford a series of carbon-carbon bond coupling products with up to 94%yield and 98%ee.Mechanistic studies such as radical clock experiment suggest that the reaction proceeds via nucleophilic attack by enamine under electrochemical conditions.展开更多
In this study,a series of hindered urea bond(HUB)containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the r...In this study,a series of hindered urea bond(HUB)containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the reactive diluent via one-pot procedure.The prepolymers were characterized fully by various techniques.Then,their thermosets were fabricated via UV curing in presence of a photo initiator,and their mechanical property and thermal behavior were investigated and compared.Different from the none HUB containing thermoset,the HUB containing thermosets(defined as PUT)could be recycled and reprocessed by hot press under relatively mild conditions with high recovery ratio of mechanical property.Furthermore,zinc oxide(ZnO)nanoparticles were modified with 3-(trimethoxysilyl)propyl methacrylate and the modified ZnO(defined as ZnO-TPM)was dispersed and polymerized into PUT matrix to prepare their nanocomposites.The influence of ZnO-TPM on the mechanical performance of the composites was evaluated,which indicated that the Young’s modulus and tensile strength increased gradually to the maximum values at ZnO-TPM content of 1 wt%and then decreased.The composites also displayed good reprocessability with improved recovery ratio compared to the pure PUT sample.In addition,the composite materials exhibited strong UV absorption capacity,implying their potential application in the circumstance where UV-shielding was required.展开更多
基金financially supported by the National Natural Science Foundation of China(NSFC)(52274295)the Natural Science Foundation of Hebei Province(E2021501029)+3 种基金the Fundamental Research Funds for the Central Universities(N2423051,N2423053,N2302016,N2423019,N2323013,N2423005)the Science and Technology Project of Hebei Education Department(QN2024238)the Basic Research Program Project of Shijiazhuang City for Universities Stationed in Hebei Province(241790937A)the Science and Technology Project of Qinhuangdao City in 2023.
文摘Mn-based layered oxides(KMO)have emerged as one of the promising low-cost cathodes for potassiumion batteries(PIBs).However,due to the multiple-phase transitions and the distortion in the MnO6structure induced by the Jahn-Teller(JT)effect associated with Mn-ion,the cathode exhibits poor structural stability.Herein,we propose a strategy to enhance structural stability by introducing robust metal-oxygen(M-O)bonds,which can realize the pinning effect to constrain the distortion in the transition metal(TM)layer.Concurrently,all the elements employed have exceptionally high crustal abundance.As a proof of concept,the designed K_(0.5)Mn_(0.9)Mg_(0.025)Ti_(0.025)Al_(0.05)O_(2)cathode exhibited a discharge capacity of approximately 100 mA h g^(-1)at 20 mA g^(-1)with 79%capacity retention over 50 cycles,and 73%capacity retention over 200 cycles at 200 mA g^(-1),showcased much better battery performance than the designed cathode with less robust M-O bonds.The properties of the formed M-O bonds were investigated using theoretical calculations.The enhanced dynamics,mitigated JT effect,and improved structural stability were elucidated through the in-situ X-ray diffractometer(XRD),in-situ electrochemical impedance spectroscopy(EIS)(and distribution of relaxation times(DRT)method),and ex-situ X-ray absorption fine structure(XAFS)tests.This study holds substantial reference value for the future design of costeffective Mn-based layered cathodes for PIBs.
文摘Organofluorines play a crucial role in medicine,agrochemicals,and materials science.Adding fluorine to molecules creates structures with specific beneficial properties or tunes properties through interactions with their environment.Many popular pharmaceuticals and agrochemicals contain fluorine because it enhances hydrogen bonding at protein’s active sites.
文摘1 As autumn becomes winter,I eagerly anticipate December's reunion with my older brother,Don,at SilverStar Mountain Resort.Our annual“SilverStar time”has reconnected us over the past decade,filling me with excitement and reflection.
基金financially supported by the Natural Science Foundation of Shandong Province(No.ZR2022MB034)。
文摘The advancement of functional adhesives featuring recyclable and repairable properties is of great significance in interfacial science and engineering.Herein,a series of high-strength,recyclable fluorine-containing adhesives(ESOx-FPF)were designed and synthesized by crosslinking two prepolymers,FPF-B(derived from side-chain fluorinated diol,isocyanate,and aminoboric acid)and ESO-B(synthesized from biobased epoxy soybean oil and aminoboric acid),through dynamic boro-oxygen bonds.The resulting adhesive exhibited an optimal tensile strength of 42 MPa and the shear strength on steel plates reached as high as 3.89 MPa.More importantly,benefiting from the dynamic reversibility of the boron-oxygen bonds along with the hydrogen bonds interaction,ESOx-FPF can be welded with the assistance of solvents and recycled for multiple cycles.The outstanding healing efficiency and excellent reprocessability of these functional adhesives were confirmed by mechanical testing.Moreover,the as-prepared adhesives demonstrated universal and remarkable adhesion to various substrates,such as aromatic polyamide,aluminum plates and polycarbonate,meanwhile,they could be easily disassembled and recycled using ethanol without damaging the substrates surface.This study not only provides a simple strategy for the synthesis of eco-friendly adhesives with weldable and recyclable properties,but also sheds light on the development of other functional materials utilizing dynamic covalent chemistry.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62404146,12174275,62174113)the Basic and Applied Basic Research Foundation of Guangdong Province,China(Grant Nos.2023A1515110730 and 2023A1515140094)the INTPART Program at the Research Council of Norway(Project number 322382)。
文摘Low-cost and large-area uniform amorphous Ga_(2)O_(3)(α-Ga_(2)O_(3))solar-blind ultraviolet(UV)detectors have garnered significant attention in recent years.Oxygen vacancy(VO)defects are generally considered as the predominant defects affecting the detector performance.Reducing VOconcentration generally results in both low dark current and low photo current,significantly limiting further improvement of the photo-to-dark current ratio(PDCR)parameter.Herein,a delicately optimized atomic layer deposition(ALD)method is revealed having the capability to break through the trade-off in a-Ga_(2)O_(3),achieving both low dark current and high photocurrent simultaneously.For a clear demonstration,a-Ga_(2)O_(3)contrast sample is prepared by magnetron sputtering and compared as well.Combined tests are performed including xray photoelectron spectroscopy,photoluminescence,electron paramagnetic resonance and Fourier-transform infrared spectroscopy.It is found that ALDα-Ga_(2)O_(3)has a lower VOconcentration,but also a lower dangling bonds concentration which are strong non-irradiation recombination centers.Therefore,decrease of dangling bonds is suggested to compensate for the low optical gain induced by low VOconcentration and promote the PDCR to~2.06×10^(6).Our findings firstly prove that the dangling bonds also play an important role in determining the a-Ga_(2)O_(3)detection performance,offering new insights for further promotion ofα-Ga_(2)O_(3)UV detector performance via dual optimization of dangling bonds and VO.
文摘With the support of the Belt and Road Initiative(BRI),the international reach of traditional Chinese medicine(TCM)is taking shape as a“Silk Road of Health,”opening new pathways for closer connections among peoples.The journey of TCM,in turn.
基金supported by the Higher Educational Youth Innovation Science and Technology Program Shandong Province(Grant Nos.2022KJ183 and 2022KJ175)the Natural Science Foundation of Shandong Province(Grant Nos.ZR2023MA016 and ZR2023JQ001)+1 种基金the National Natural Science Foundation of China(Grant Nos.11974208 and 12374012)financial support from the award of Taishan Scholar(Grant No.tsqn202211128).
文摘The activation of the N≡N triple bond in N_(2) is a fascinating topic in nitrogen chemistry.The transition metals have been demonstrated to effectively modulate the reactivity of N_(2) molecules under high pressure,leading to nitrogen-rich compounds.However,their use often results in a significant reduction in energy density.In this work,we propose a series of low-enthalpy nitrogen-rich phases in CN_(x)(x=3,...,7)compounds using a first-principles crystal structure search method.The results of calculations reveal that all these CN compounds are assembled from both CN_(4) tetrahedra and N_(x)(x=1,2,or 5)species.Strikingly,we find that the CN_(4) tetrahedron can effectively activate the N≡N bond through weakening of the π orbital of N_(2) under a pressure of 40 GPa,leading to stable CN polynitrides.The robust structural framework of CN polynitrides containing C-N and N-N bonds plays a crucial role in enhancing their structural stability,energy density,and hardness.Among these polynitrides,CN_(6) possesses not only a very high mass density of 3.19 g/cm^(3),but also an ultrahigh energy density of 28.94 kJ/cm^(3),which represents a significant advance in the development of energetic materials using high-pressure methods.This work provides new insights into the mechanism of N_(2) activation under high pressure,and offers a promising pathway to realize high-performance energetic materials.
文摘Green bonds, as one of the core tools of green finance, have rapidly developed into a large-scale and far-reaching financial market since the first green bond was issued in 2007. As a direct financing channel for green projects, green bonds have promoted the rapid development of green finance in China, and under the background of “dual carbon”, the demand for green bonds in China has increased significantly. In fact, the Chinese green bond investment market has vast development space. However, due to its late start and immature development, there are doubts about whether green bonds can play a positive role in enhancing the company’s value. Therefore, it is urgent to conduct in-depth analysis of the impact of the company’s issuance of green bonds on its value. In this paper, we used Tobin’s Q to measure company value, and used panel data to explore the impact of issuing green bonds on company value through propensity score matching method. It explored the significant improvement effect of issuing green bonds and increasing their intensity on company value;and then, by analyzing the mediating effect on the impact mechanism of company value, efforts are made to discover that green bonds can enhance company value by alleviating financing constraints and improving information transparency. Finally, based on the conclusions drawn, reasonable suggestions are proposed, which have practical reference value for the development of the green bond market and the construction of a green financial system.
基金supported by the National Key R&D Program of China(No.2021YFC2103600)the National Natural Science Foundation of China(Nos.21878156,21978131,22275085,and 22278224)+2 种基金the Natural Science Foundation of Jiangsu Province(Nos.BK20200089 and BK20200691)the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the State Key Laboratory of Materials-Oriented Chemical Engineering(No.KL21-08).
文摘Constructing multi-dimensional hydrogen bond(H-bond)regulated single-molecule systems with multiemission remains a challenge.Herein,we report the design of a new excited-state intramolecular proton transfer(ESIPT)featured chromophore(HBT-DPI)that shows flexible emission tunability via the multidimensional regulation of intra-and intermolecular H-bonds.The feature of switchable intramolecular Hbonds is induced via incorporating several hydrogen bond acceptors and donors into one single HBT-DPI molecule,allowing the“turn on/off”of ESIPT process by forming isomers with distinct intramolecular Hbonds configurations.In response to different external H-bonding environments,the obtained four types of crystal/cocrystals vary in the contents of isomers and the molecular packing modes,which are mainly guided by the intermolecular H-bonds,exhibiting non-emissive features or emissions ranging from green to orange.Utilizing the feature of intermolecular H-bond guided molecular packing,we demonstrate the utility of this fluorescent material for visualizing hydrophobic/hydrophilic areas on large-scale heterogeneous surfaces of modified poly(1,1-difluoroethylene)(PVDF)membranes and quantitatively estimating the surface hydrophobicity,providing a new approach for hydrophobicity/hydrophilicity monitoring and measurement.Overall,this study represents a new design strategy for constructing multi-dimensional hydrogen bond regulated ESIPT-based fluorescent materials that enable multiple emissions and unique applications.
文摘Launched in December 2021,the China-Laos Railway(CLR)has created ample opportunities for the development of Laos’crop production,food processing,and manufacturing.A powerful booster to infrastructure connectivity and trade relations between the two countries,the rail project has also opened a door for young people in Laos through vocational training and education cooperation,strengthening the bonds of friendship between the two peoples.
文摘The intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates(H_(ad))to form strong S-H_(ad) bonds,resulting in a low photocatalytic H_(2) evolution activity.Herein,a cobalt-induced asymmetric electronic distribution is justified as an effective strategy to optimize the electronic configuration of catalytic S sites in NiCoS cocatalysts for highly active photocatalytic H_(2) evolution.To this end,Co atoms are uniformly incorporated in NiS nanoparticles to fabricate homogeneous NiCoS cocatalyst on TiO_(2) surface by a facile photosynthesis strategy.It is revealed that the incorporated Co atoms break the electron distribution symmetry in NiS,thus essentially increasing the electron density of S atoms to form active electron-enriched S^(2+δ)–sites.The electron-enriched S^(2+δ)–sites could interact with Had via an increased antibonding orbital occupancy,which weakens S–Had bonds for efficient H_(ad) adsorption and desorption,endowing the NiCoS cocatalysts with a highly active H_(2) evolution process.Consequently,the optimized NiCoS/TiO_(2)(1:2)photocatalyst displays the highest H_(2) production performance,outperforming the NiS/TiO_(2) and CoS/TiO_(2) samples by factors of 2.1 and 2.5,respectively.This work provides novel insights on breaking electron distribution symmetry to optimize catalytic efficiency of active sites.
文摘The efficient conversion of lignin into mono-cycloalkanes via both C–O and C–C bonds cleavage are attractive,but challenging due to the high C–C bond dissociation energy.Previous studies have demonstrated that NbO_(x)-based catalysts exhibited exceptional capabilities for C_(Ar)–C bond cleavage and broken the limitation of lignin monomers.In this work,we presented an economical multifunctional Pt-Nb/MOR catalyst that achieved an impressive monomer yield of 147%during the depolymerization and hydrodeoxygenation of lignin into mono-cycloalkanes.Reaction pathway studies showed that unlike traditional NbO_(x)-based catalytic system,bicyclohexane was an important intermediate in this system and followed the C_(sp3)–C_(sp3)cleavage pathway after complete cyclic-hydrogenation.Deep investigations demonstrated that the doping of Nb in Pt/MOR not only enhanced the activation of hydrogen by Pt,but also increased the acidity of MOR,both of these are favor for the hydrogenolytic cleavage of C_(sp3)–C_(sp3)bonds.This work provides a low-cost catalyst to obtain high-yield monomers from lignin under relatively mild conditions and would help to design catalysts with higher activity for the valorization of lignin.
基金supported by the National Natural Science Foundation of China(Nos.22078118 and 42277219)the Natural Science Foundation of Guangdong Province,China(No.2023A1515010740).
文摘A novel photocatalytic cocatalyst, MoC quantum dots integrated into N-doped carbon microflowers (MoC–NC), was synthesized, establishing a key Mo–N interfacial bond. The Mo–N bond's regulation was achieved by adjusting the pH of Mo-polydopamine precursor solutions. A composite photocatalyst, MoC–NC/CdS (MNS), was formed by in situ growth of nano-CdS on MoC–NC. The pH during synthesis, crucial for Mo–N bond formation, significantly influenced Cr(Ⅵ) reduction and H_(2) evolution performance. The optimal MNS, created at pH 9.0, demonstrated 99.2% reduction efficiency for Cr(Ⅵ) in 20 min and H_(2) evolution rate of 11.4 mmol g^(-1) h^(-1) over 3 h, outperforming Pt/CdS. Mechanistic studies and density functional theory revealed MoC–NC's role in enhancing light absorption, reaction kinetics, and electron transport, attributing to its ultra-small quantum dots and abundant Mo–N bonds.
基金the National Natural Science Foundation of China(Nos.22371273,22293011 and T2341001)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2023476)the National Science Foundation of Anhui Province(No.2208085J26)。
文摘Transition-metal-catalyzed cross-electrophile coupling has emerged as a reliable method for constructing carbon–carbon bonds.Herein,we report a general method,cobalt-catalyzed reductive alkynylation,to construct C(sp)-C(sp^(3))and C(sp)-C(sp^(2))bonds.This presented reaction has a broad substrate scope,enabling the efficient cross-electrophile coupling between alkynyl bromides with alkyl halides and aryl or alkenyl(pseudo)halides.This presented reaction is conducted under mild conditions,tolerating many functional groups,thus suitable for the modification and synthesis of biologically active molecules.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52033011,51973237 and 52373095)Natural Science Foundation of Guangdong Province,China(Nos.2019B1515120038 and 2021A1515010417)+2 种基金Science and Technology Planning Project of Guangdong Province(No.2020B010179001)Science and Technology Planning Project of Guangzhou City(No.202201011568)GBRCE for Functional Molecular Engineering,and Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.23yxqntd002).
文摘To simultaneously endow thermal conductivity,high glass transition temperature(Tg)and healing capability to glass fiber/epoxy(GFREP)composite,dynamic crosslinked epoxy resin bearing reversibleβ-hydroxyl ester bonds was reinforced with boron nitride nanosheets modified glass fiber cloth(GFC@BNNSs).The in-plane heat conduction paths were constructed by electrostatic self-assembly of polyacrylic acid treated GFC and polyethyleneimine decorated BNNSs.Then,the GFC@BNNSs were impregnated with the mixture of lower concentration(3-glycidyloxypropyl)trimethoxysilane grafted BN micron sheets,3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and hexahydro-4-methylphthalic anhydride,which accounted for establishing the through-plane heat transport pathways and avoiding serious deterioration of mechanical performances.The resultant GFREP composite containing less boron nitride particles(17.6 wt%)exhibited superior in-plane(3.29 W·m^(-1)·K^(-1))and through-plane(1.16 W·m^(-1)·K^(-1))thermal conductivities,as well as high Tg of 204℃(Tg of the unfilled epoxy=177℃).The reversible transesterification reaction enabled closure of interlaminar cracks within the composite,achieving decent healing efficiencies estimated by means of tensile strength(71.2%),electrical breakdown strength(83.6%)and thermal conductivity(69.1%).The present work overcame the disadvantages of conventional thermally conductive composites,and provided an efficient approach to prolong the life span of thermally conductive GFREP laminate for high-temperature resistant integrated circuit application.
基金financially supported by the National Natural Science Foundation of China(31890771)the Young Elite Scientists Sponsorship Program from the National Forestry and Grassland Administration of China(2019132614)+1 种基金the Science and Technology Innovation Program of Hunan Province(2022RC3054)the Hunan Provincial Innovation Foundation for Postgraduate(CX20230758)。
文摘Lithium-sulfur batteries(LSBs)are considered promising candidates for next-generation battery technologies owing to their outstanding theoretical energy density and cost-effectiveness.However,the low conductivity and polysulfide shuttling effect of S cathodes severely hamper the practical performance of LSBs.Herein,in situ-generated single layer MXene nanosheet/hierarchical porous carbonized wood fiber(MX/PCWF)composites are prepared via a nonhazardous eutectic activation strategy coupled with pyrolysis-induced gas diffusion.The unique architecture,wherein single layer MXene nanosheets are constructed on carbonized wood fiber walls,ensures rapid polysulfide conversion and continuous electron transfer for redox reactions.The C-Ti-C bonds formed between MXene and PCWF can considerably expedite the conversion of polysulfides,effectively suppressing the shuttle effect.An impressive capacity of 1301.1 m A h g^(-1)at 0.5 C accompanied by remarkable stability is attained with the MX/PCWF host,as evidenced by the capacity maintenance of 722.6 m A h g^(-1)after 500 cycles.Notably,the MX/PCWF/S cathode can still deliver a high capacity of 886.8 m A h g^(-1)at a high S loading of 5.6 mg cm^(-2).The construction of two-dimensional MXenes on natural wood fiber walls offers a competitive edge over S-based cathode materials and demonstrates a novel strategy for developing high-performance batteries.
基金supported by the National Natural Science Foundation of China(22178190).
文摘In the petrochemical industry process, the relative volatility between the components to be separated is close to one or the azeotrope that systems are difficult to separate. Liquid-liquid extraction is a common and effective separation method, and selecting an extraction agent is the key to extraction technology research. In this paper, a design method of extractants based on elements and chemical bonds was proposed. A knowledge-based molecular design method was adopted to pre-select elements and chemical bond groups. The molecules were automatically synthesized according to specific combination rules to avoid the problem of “combination explosion” of molecules. The target properties of the extractant were set, and the extractant meeting the requirements was selected by predicting the correlation physical properties of the generated molecules. Based on the separation performance of the extractant in liquid-liquid extraction and the relative importance of each index, the fuzzy comprehensive evaluation membership function was established, the analytic hierarchy process determined the mass ratio of each index, and the consistency test results were passed. The results of case study based on quantum chemical analysis demonstrated that effective determination of extractants for the analysis of benzene-cyclohexane systems. The results unanimously prove that the method has important theoretical significance and application value.
基金financially supported by the National Natural Science Foundation of China(No.51973176)the Chongqing Talent Plan for Young Top-Notch Talents(No.CQYC2021059217)the Fundamental Research Funds for the Central Universities(No.SWUXDJH202314)。
文摘Poly(butylene succinate)(PBS)exhibits many advantages,such as renewability,biodegradability,and impressive thermal and mechanical properties,but is limited by the low melt viscosity and strength resulted from the linear structure.To address this,vitrimeric network was introduced to synthesize PBS vitrimers(PBSVs)based on dynamic imine bonds through melt polymerization of hydroxyl-terminated PBS with vanillin derived imine containing compound and hexamethylene diisocyanate using trimethylolpropane as a crosslinking monomer.PBSVs with different crosslinking degrees were synthesized through changing the content of the crosslinking monomer.The effect of crosslinking degree on the thermal,theological,mechanical properties,and stress relaxation behavior of the PBSVs was studied in detail.The results demonstrated that the melt viscosity,melt strength,and heat resistance were enhanced substantially without obvious depression in crystallizability,thermal stability,and mechanical properties through increasing crosslinking degree.In addition,the PBSVs exhibit thermal reprocessability with mechanical properties recovered by more than 90%even after processing for three times.Furthermore,PBSV with improved melt properties shows significantly improved foamability compared to commercial PBS.This research contributes to the advancement of polymer technology by successfully developing PBS vitrimers with improved properties,showcasing their potential applications in sustainable and biodegradable materials.
基金National Natural Science Foundation of China(Nos.22161008,22061003)Guangxi Science and Technology Base and Talent Project(High Level Innovative Talents and Team Training)(Guike No.AD23026094)Guangxi Natural Science Foundation of China(No.2021GXNSFFA220005)for financial support。
文摘An efficient and scalable electrochemical asymmetric protocol with metal-free catalysts and even without additional oxidants for the cross-dehydrogenative coupling reaction(CDC)of two C(sp^(3))-H bonds is reported.A series of aldehydes including natural products and various substrates containing C(sp^(3))-H bonds including xanthenes,acridines,cycloheptatrienes and even diarylmethane have been shown to undergo asymmetric CDC to afford a series of carbon-carbon bond coupling products with up to 94%yield and 98%ee.Mechanistic studies such as radical clock experiment suggest that the reaction proceeds via nucleophilic attack by enamine under electrochemical conditions.
文摘In this study,a series of hindered urea bond(HUB)containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the reactive diluent via one-pot procedure.The prepolymers were characterized fully by various techniques.Then,their thermosets were fabricated via UV curing in presence of a photo initiator,and their mechanical property and thermal behavior were investigated and compared.Different from the none HUB containing thermoset,the HUB containing thermosets(defined as PUT)could be recycled and reprocessed by hot press under relatively mild conditions with high recovery ratio of mechanical property.Furthermore,zinc oxide(ZnO)nanoparticles were modified with 3-(trimethoxysilyl)propyl methacrylate and the modified ZnO(defined as ZnO-TPM)was dispersed and polymerized into PUT matrix to prepare their nanocomposites.The influence of ZnO-TPM on the mechanical performance of the composites was evaluated,which indicated that the Young’s modulus and tensile strength increased gradually to the maximum values at ZnO-TPM content of 1 wt%and then decreased.The composites also displayed good reprocessability with improved recovery ratio compared to the pure PUT sample.In addition,the composite materials exhibited strong UV absorption capacity,implying their potential application in the circumstance where UV-shielding was required.
