Using porous carbon hosts in cathodes of Li-S cells can disperse S actives and offset their poor electrical conductivity.However,such reservoirs would in turn absorb excess electrolyte solvents to S-unfilled regions,c...Using porous carbon hosts in cathodes of Li-S cells can disperse S actives and offset their poor electrical conductivity.However,such reservoirs would in turn absorb excess electrolyte solvents to S-unfilled regions,causing the electrolyte overconsumption,specific energy decline,and even safety hazards for battery devices.To build better cathodes,we propose to substitute carbons by In-doped SnO_(2)(ITO)nano ceramics that own three-in-one functionalities:1)using conductive ITO enables minimizing the total carbon content to an extremely low mass ratio(~3%)in cathodes,elevating the electrode tap density and averting the electrolyte overuse;2)polar ITO nanoclusters can serve as robust anchors toward Li polysulfide(LiPS)by electrostatic adsorption or chemical bond interactions;3)they offer catalysis centers for liquid–solid phase conversions of S-based actives.Also,such ceramics are intrinsically nonflammable,preventing S cathodes away from thermal runaway or explosion.These merits entail our configured cathodes with high tap density(1.54 g cm^(−3)),less electrolyte usage,good security for flame retardance,and decent Li-storage behaviors.With lean and LiNO_(3)-free electrolyte,packed full cells exhibit excellent redox kinetics,suppressed LiPS shuttling,and excellent cyclability.This may trigger great research enthusiasm in rational design of low-carbon and safer S cathodes.展开更多
Two-dimensional carbon-based materials have shown promising electromagnetic wave absorption capabilities in mid-and high-frequency ranges,but face challenges in low-frequency absorption due to limited control over pol...Two-dimensional carbon-based materials have shown promising electromagnetic wave absorption capabilities in mid-and high-frequency ranges,but face challenges in low-frequency absorption due to limited control over polarization response mecha-nisms and ambiguous resonance behavior.In this study,we pro-pose a novel approach to enhance absorption efficiency in aligned three-dimensional(3D)MXene/CNF(cellulose nanofibers)cavities by modifying polarization properties and manipulating resonance response in the 3D MXene architecture.This controlled polarization mechanism results in a significant shift of the main absorption region from the X-band to the S-band,leading to a remarkable reflection loss value of-47.9 dB in the low-frequency range.Furthermore,our findings revealed the importance of the oriented electromagnetic coupling in influencing electromagnetic response and microwave absorption properties.The present study inspired us to develop a generic strategy for low-frequency tuned absorption in the absence of magnetic element participation,while orientation-induced polarization and the derived magnetic resonance coupling are the key controlling factors of the method.展开更多
To explore the distribution of and the mechanical properties(compressive strength)of the hardened body of alkali slag-fly ash cementitious materials,this study was conducted by using the XRD,FTIR,SEM/EDS,and other tes...To explore the distribution of and the mechanical properties(compressive strength)of the hardened body of alkali slag-fly ash cementitious materials,this study was conducted by using the XRD,FTIR,SEM/EDS,and other test methods in three conditions:airtight drying(AD),airtight immersion(AI),and airtight soaking(AS).The 1D distribution law of free of hardened body under standard curing conditions was explored.The experimental results show that under standard curing conditions,the 1D distribution of within 0d-3 d shows a∨-shaped distribution,within 3-7 d show a∧-shaped distribution,and within 7-28 d tends to be balanced.The test results of leaching rate show that the free was the most stable under AD conditions and the hardened body bound the most by XRD,FTIR and SEM/EDS.And the compressive strength of the hardened body was the highest.The compressive strength of 28th reached 95.9 MPa.The definite distribution of provides an important reference for the strength development and durability evaluation of the hardened body of alkaliexcited cementitious materials.展开更多
The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple ...The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple one-step pyrolysis strategy.The experimental results and density functional theory(DFT)calculation show that the formation of FeCo alloy is conducive to promoting electron transfer,and the introduction of S atom can enhance the interaction between FeCo alloy and carbon substrate,thus inhibiting the migration and agglomeration of particles on the surface of carbon material.The FeCo/SNC catalysts show outstanding performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).FeCo/S-NC shows a high half-wave potential(E_(1/2)=0.8823 V)for ORR and a low overpotential at 10 mA cm^(-2)(E_(j=10)=299 mV)for OER.In addition,compared with Pt/C+RuO_(2) assembled Zn-air battery(ZAB),the FeCo/S-NC assembled ZAB exhibits a larger power density(198.8 mW cm^(-2)),a higher specific capacity(786.1 mA h g_(zn)~(-1)),and ultra-stable cycle performance.These results confirm that the optimized composition and the interfacial interaction between catalyst and carbon substrate synergistically enhance the electrochemical performance.展开更多
The development of highly effective metal-zeolite bifunctional catalysts for the hydroisomerization of n-alkanes is a paramount strategy to produce second-generation biofuels with high quality.In this study,polyhexame...The development of highly effective metal-zeolite bifunctional catalysts for the hydroisomerization of n-alkanes is a paramount strategy to produce second-generation biofuels with high quality.In this study,polyhexamethylene biguanide hydrochloride(PHMB)is precisely added to the initial gel to synthesize nanosized ZSM-23 zeolites(Z23-x PH).Due to orientation adsorption and steric hindrance effects of PHMB,each sample of Z23-x PH demonstrates enhanced mesoporosity in comparison with the conventional Z23-C zeolite.Furthermore,the Bronsted acid density of the Z23-x PH samples is also signifi cantly reduced due to a reduction in the distribution of framework Al at T2-T5 sites.The corresponding Pd/23-C and Pd/Z23-x PH bifunctional catalysts with 0.5 wt%Pd loading for n-hexadecane hydroisomerization are prepared by incorporating ZSM-23 zeolites as acid supports.According to the catalytic test results,the suitable addition of PHMB can effectively promote the iso-hexadecane yield.The Pd/Z23-2PH catalyst with an n_(PHMB)/n(_Si)molar ratio of 0.002 demonstrates the highest maximum iso-hexadecane yield of 74.1%at an n-hexadecane conversion of 88.3%.Therefore,the employment of PHMB has provided a simple route for the development of highly effective Pd/ZSM-23 catalysts for n-alkane hydroisomerization.展开更多
Isosorbide is a novel bio-based material derived as a secondary dehydration product of sorbitol.This work focuses on the kinetics of sulfuric acid-catalyzed dehydration of sorbitol under conditions of nonconstant volu...Isosorbide is a novel bio-based material derived as a secondary dehydration product of sorbitol.This work focuses on the kinetics of sulfuric acid-catalyzed dehydration of sorbitol under conditions of nonconstant volume.Herein,the effects of stirring rate,catalyst dosage,reaction temperature,and reaction time on the dehydration reaction of sorbitol were investigated.The yield of isosorbide up to 77.13%was obtained after 1.5 h of reaction time under conditions of 2 kPa,1.0%(mass)catalyst dosage,and 413.15 K.Based on the sorbitol dehydration reaction mechanism and a simplified reaction network,a kinetic model was developed in this work.A good agreement was accomplished between kinetic modeling and experiments between 393.15 and 423.15 K.The fitting results indicate that side reactions with higher activation energies are more affected by reaction temperatures,and the main side reaction that influences the selectivity of isosorbide is the oligomerization reaction among the primary dehydration products of sorbitol.The model fitting of the catalyst amounts effect shows that the effective concentration of sulfuric acid would be reduced with the increase of dosage due to the molecular agglomeration effect.Hopefully,the kinetic experiments and modeling results obtained in this work will be helpful to the design and optimization of the industrial sorbitol dehydration process.展开更多
The exploration of antibiotic-independent phototherapy strategies for the treatment of bacterial biofilm infections has gained significant attention.However,efficient eradication of bacterial biofilms remains a challenge....The exploration of antibiotic-independent phototherapy strategies for the treatment of bacterial biofilm infections has gained significant attention.However,efficient eradication of bacterial biofilms remains a challenge.Herein,a self-regulated pho-totheranostic nanosystem with single wavelength-triggered photothermal therapy(PTT)/photodynamic therapy(PDT)transformation and oxygen supply for multi-modal synergistic therapy of bacterial biofilm infections is presented.This approach combines a eutectic mixture of natural phase-change materials(PCMs)and an aggregation-induced emission(AIE)phototheranostic agent TPA-ICN to form col-loidally stable nanopartcicles(i.e.AIE@PCM NPs).The reversible solid-liquid phase transition of PCMs facilitates the adaptive regulation of the aggregation states of TPA-ICN,enabling a switch between the energy dissipation pathways for enhanced PDT in solid PCMs or enhanced PTT in liquid PCMs.Addition-ally,oxygen-carrying thermoresponsive nanoparticles are also introduced to alleviate the hypoxic microenvironment of biofilms by releasing oxygen upon heating by AIE@PCM NPs with enhanced PTT.The nanosystem exhibits outstanding therapeu-tic efficacy against bacterial biofilms both in vitro and in vivo,with an antibacterial efficiency of 99.99%.This study utilizes a self-regulated theranostic nanoplatform with adaptive PTT/PDT transformation via the phase transition of PCMs and heat-triggered oxygen release,holding great promise in the safe and efficient treatment of bacterial biofilm infections.展开更多
Controlling the growth of bacterial biofilms in a specific pattern greatly enhances the study of cell-to-cell interactions and paves the way for expanding their biolog-ical applications.However,the development of simple...Controlling the growth of bacterial biofilms in a specific pattern greatly enhances the study of cell-to-cell interactions and paves the way for expanding their biolog-ical applications.However,the development of simple,cost-effective,and highly resolved biopatterning approaches remains a persistent challenge.Herein,a pio-neering photodynamic biopatterning technique for the creation of living bacterial biofilms with customized geometries at high resolutions is presented.First of all,an outstanding aggregation-induced emission photosensitizer is synthesized to enable efficient photodynamic bacterial killing at a low concentration.By combining with custom-designed photomasks featuring both opaque and transparent patterns,the viability of photosensitizer-coated bacteria is successfully manipulated by control-ling the degree of light transmittance.This process leads to the formation of living bacterial biofilms with specific patterns replicated from the photomask.Such an innovative strategy can be employed to generate living bacterial biofilms composed of either mono-or multispecies,with a spatial resolution of approximately 24µm.Furthermore,its potential applications in information storage/encryption and antibi-otic screening are explored.This study provides an alternative way to understand and investigate the intricate interactions among bacteria within 3D biofilms,hold-ing great promise in the controlled fabrication of dynamic biological systems for advanced applications.展开更多
The high-pressure structure and elastic properties of calcium azide(Ca(N_(3))_(2))were investigated using in-situ highpressure x-ray diffraction and Raman scattering up to 54 GPa and 19 GPa,respectively.The compressib...The high-pressure structure and elastic properties of calcium azide(Ca(N_(3))_(2))were investigated using in-situ highpressure x-ray diffraction and Raman scattering up to 54 GPa and 19 GPa,respectively.The compressibility of Ca(N_(3))_(2)changed as the pressure increased,and no phase transition occurred within the pressure from ambient pressure up to 54 GPa.The measured zero-pressure bulk modulus of Ca(N_(3))_(2)is higher than that of other alkali metal azides,due to differences in the ionic character of their metal-azide bonds.Using CASTEP,all vibration modes of Ca(N_(3))_(2)were accurately identified in the vibrational spectrum at ambient pressure.In the high-pressure vibration study,several external modes(ext.)and internal bending modes(ν_(2))of azide anions(N_(3)^(-))softened up to~7 GPa and then hardened beyond that pressure.This evidence is consistent with the variation observed in the F_(E)–f_(E)data analyzed from the XRD result,where the slope of the curve changes at 7.1 GPa.The main behaviors under pressure are the alternating compression,rotation,and bending of N_(3)^(-)ions.The bending behavior makes the structure of Ca(N_(3))_(2)more stable under pressure.展开更多
Monodisperse hollow polymer microspheres having various functional groups on the shell-layer, such as carboxylic acid, pyridyl and amide, were prepared by two-stage distillation precipitation polymerization in neat ac...Monodisperse hollow polymer microspheres having various functional groups on the shell-layer, such as carboxylic acid, pyridyl and amide, were prepared by two-stage distillation precipitation polymerization in neat acetonitrile in the absence of any stabilizer or additive, during which monodisperse poly（methacrylic acid） （PMAA） afforded from the first-stage polymerization was utilized as the seeds for the second-stage polymerization. The shell layer with different functional groups was formed during the second-stage copolymerization of either divinylbenzene （DVB） or ethyleneglycol dimethacrylate （EGDMA） as crosslinker and the functional comonomers, in which the hydrogen-bonding interaction between the carboxylic acid group of PMAA core and the functional groups of the corresponding comonomers, including carboxylic acid, amide and pyridyl, played an essential role for the formation of monodisperse core-shell functional microspheres. The hollow polymer microspheres were then developed after the subsequent removal of PMAA cores by dissolution in ethanol under basic condition. Transmission electron microscopy （TEM） and scanning electron microscopy （SEM） were used to determine the morphology of the resultant PMAA core, functional core-shell microspheres and the corresponding hollow polymer microspheres with different functional groups. FT-IR spectra confirmed the successful incorporation of the various functional groups on the shell layer of the hollow polymer microspheres.展开更多
One of the most general methods to enhance the separation of photogenerated carriers for g‐C3N4is to construct a suitable heterojunctional composite,according to the principle of matching energy levels.The interface ...One of the most general methods to enhance the separation of photogenerated carriers for g‐C3N4is to construct a suitable heterojunctional composite,according to the principle of matching energy levels.The interface contact in the fabricated nanocomposite greatly influences the charge transfer and separation so as to determine the final photocatalytic activities.However,the role of interface contact is often neglected,and is rarely reported to date.Hence,it is possible to further enhance the photocatalytic activity of g‐C3N4‐based nanocomposite by improving the interfacial connection.Herein,phosphate-oxygen(P-O)bridged TiO2/g‐C3N4nanocomposites were successfully synthesized using a simple wet chemical method,and the effects of the P-O functional bridges on the photogenerated charge separation and photocatalytic activity for pollutant degradation and CO2reduction were investigated.The photocatalytic activity of g‐C3N4was greatly improved upon coupling with an appropriate amount of nanocrystalline TiO2,especially with P-O bridged TiO2.Atmosphere‐controlled steady‐state surface photovoltage spectroscopy and photoluminescence spectroscopy analyses revealed clearly the enhancement of photogenerated charge separation of g‐C3N4upon coupling with the P-O bridged TiO2,resulting from the built P-O bridges between TiO2and g‐C3N4so as to promote effective transfer of excited electrons from g‐C3N4to TiO2.This enhancement was responsible for the improved photoactivity of the P-O bridged TiO2/g‐C3N4nanocomposite,which exhibited three‐time photocatalytic activity enhancement for2,4‐dichlorophenol degradation and CO2reduction compared with bare g‐C3N4.Furthermore,radical‐trapping experiments revealed that the·OH species formed as hole‐modulated direct intermediates dominated the photocatalytic degradation of2,4‐dichlorophenol.This work provides a feasible strategy for the design and synthesis of high‐performance g‐C3N4‐based nanocomposite photocatalysts for pollutant degradation and CO2reduction.展开更多
Li_(5)Cr_(7)Ti_(6)O_(25) is regarded as a promising anode material for Li-ion batteries(LIBs)because of its low cost and high theoretical capacity.However,the inherently poor conductivity significantly limits the enha...Li_(5)Cr_(7)Ti_(6)O_(25) is regarded as a promising anode material for Li-ion batteries(LIBs)because of its low cost and high theoretical capacity.However,the inherently poor conductivity significantly limits the enhancement of its rate capability and cycling stability,especially at high current densities.In this work,we construct one-dimensional Li_(5)Cr_(7)Ti_(6)O_(25)/C nanofibers by electrospinning method to enhance the kinetic,which realizes high cycling stability.Carbon coating enhances the structure stability,insertion/extraction reversibility of Li-ions and electrochemical reaction activity,and facilitates the transfer of Li-ions.Benefited from the unique architecture and component,the Li_(5)Cr_(7)Ti_(6)O_(25)/C(6.6 wt%)nanofiber shows an excellent rate capability with a reversible de-lithiation capacity of 370.8,290.6,269.2,254.3 and 244.9 m Ah g^(-1) at 200,300,500,800 and 1000 m A g^(-1),respectively.Even at a higher current density of 1 A g^(-1),Li_(5)Cr_(7)Ti_(6)O_(25)/C(6.6 wt%)nanofiber shows high cycling stability with an initial de-lithiation capacity of 237.8 m Ah g^(-1) and a capacity retention rate of about 84%after 500 cycles.The density functional theory calculation result confirms that the introduction of carbon on the surface of Li_(5)Cr_(7)Ti_(6)O_(25) changes the total density of states of Li_(5)Cr_(7)Ti_(6)O_(25),and thus improves electronic conductivity of the composite,resulting in a good electrochemical performance of Li_(5)Cr_(7)Ti_(6)O_(25)/C nanofibers.Li_(5)Cr_(7)Ti_(6)O_(25)/C nanofibers indicate a great potential as an anode material for the next generation of high-performance LIBs.展开更多
A new photon-in/photon-out endstation at beamline 02B02 of the Shanghai Synchrotron Radiation Facility for studying the electronic structure of energy materials has been constructed and fully opened to users.The endst...A new photon-in/photon-out endstation at beamline 02B02 of the Shanghai Synchrotron Radiation Facility for studying the electronic structure of energy materials has been constructed and fully opened to users.The endstation has the capability to perform soft x-ray absorption spectroscopy in total electron yield and total fluorescence yield modes simultaneously.The photon energy ranges from 40 eV to 2000 eV covering the K-edge of most low Z-elements and the L-edge of 3d transition-metals.The new self-designed channeltron detector allows us to achieve good fluorescence signals at the low photon flux.In addition,we synchronously collect the signals of a standard reference sample and a gold mesh on the upstream to calibrate the photon energy and monitor the beam fluctuation,respectively.In order to cross the pressure gap,in situ gas and liquid cells for soft x-ray absorption spectroscopy are developed to study the samples under realistic working conditions.展开更多
The hardening of the buried oxide （BOX） layer of separation by implanted oxygen （SIMOX） silicon-on-insulator （SOI） wafers against total-dose irradiation was investigated by implanting ions into the BOX layers. T...The hardening of the buried oxide （BOX） layer of separation by implanted oxygen （SIMOX） silicon-on-insulator （SOI） wafers against total-dose irradiation was investigated by implanting ions into the BOX layers. The tolerance to total-dose irradiation of the BOX layers was characterized by the comparison of the transfer characteristics of SOI NMOS transistors before and after irradiation to a total dose of 2.7 Mrad（SiO2）. The experimental results show that the implantation of silicon ions into the BOX layer can improve the tolerance of the BOX layers to total-dose irradiation. The investigation of the mechanism of the improvement suggests that the deep electron traps introduced by silicon implantation play an important role in the remarkable improvement in radiation hardness of SIMOX SOI wafers.展开更多
The electrocatalytic oxidation of nitric oxide（NO） at a glass carbon electrode（GC） modified with functionalized single-walled carbon nanotubes（SWCNTs） was investigated by cyclic voltammetry（CV） and electrochem...The electrocatalytic oxidation of nitric oxide（NO） at a glass carbon electrode（GC） modified with functionalized single-walled carbon nanotubes（SWCNTs） was investigated by cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）.It was found that the SWCNT modified electrode could speed greatly up the electron transfer rate compared with the bare GC electrode.After the SWCNT was treated with alkali or mixed acids,the reaction rate and activation energy of NO electrooxidation were changed to different extent.Chemical modification of the SWCNT surface is one of the most powerful methods to change the sensitivity of NO electrooxidation reaction.The modified electrode with SWCNT obtained by the firstly alkali treatment and then the mixed acids treatment was the best one for NO electrooxidation,the result of CV was also confirmed by that of EIS.The anodic processes of NO were recognized more clearly by exploring the reaction mechanism of NO electrooxidation at the SWCNT modified electrode.展开更多
In the search of alternative resources to make commodity chemicals and transportation fuels for a low carbon future,lignocellulosic biomass with over 180-billion-ton annual production rate has been identified as a pro...In the search of alternative resources to make commodity chemicals and transportation fuels for a low carbon future,lignocellulosic biomass with over 180-billion-ton annual production rate has been identified as a promising feedstock.This review focuses on the state-of-the-art catalytic transformation of lignocellulosic biomass into value-added chemicals and fuels.Following a brief introduction on the structure,major resources and pretreatment methods of lignocellulosic biomass,the catalytic conversion of three main components,i.e.,cellulose,hemicellulose and lignin,into various compounds are comprehensively discussed.Either in separate steps or in one-pot,cellulose and hemicellulose are hydrolyzed into sugars and upgraded into oxygen-containing chemicals such as 5-HMF,furfural,polyols,and organic acids,or even nitrogen-containing chemicals such as amino acids.On the other hand,lignin is first depolymerized into phenols,catechols,guaiacols,aldehydes and ketones,and then further transformed into hydrocarbon fuels,bioplastic precursors and bioactive compounds.The review then introduces the transformations of whole biomass via catalytic gasification,catalytic pyrolysis,as well as emerging strategies.Finally,opportunities,challenges and prospective of woody biomass valorization are highlighted.展开更多
Electrochemical reduction of nitrate,a common pollutant in aquatic environment,to valuable ammonia(NO3-RR) using renewably-sourced electricity has attracted widespread interests,with past efforts mainly focused on des...Electrochemical reduction of nitrate,a common pollutant in aquatic environment,to valuable ammonia(NO3-RR) using renewably-sourced electricity has attracted widespread interests,with past efforts mainly focused on designing electrocatalysts with high activity and selectivity.The detailed correlation between catalyst properties and NO3-RR kinetics,nevertheless,is still not fully understood.In this work,we modulate the surface oxygen species of Cu_(2)O via facet engineering,and systematically study the impact of these oxygen species on the NO_(3)^(-)RR activity.Combining advanced spectroscopic techniques,densi ty fu n ctional theory calculations and molecular dynamics simulations,we find that while oxygen vacancies on Cu_(2)O(111) surface promote the adsorption of reactants and reaction intermediates,hydroxyl groups effectively inhibit the side reaction of hydrogen evolution and facilitate the hydrogenation process of NO3-RR.These two effects work in concert to render Cu_(2)O(111) facet the highest NO3-RR activity relative to those from other facets.Our study provides critical insights into the synergistic effect of exposed facets and surface oxygen species on heterogeneous catalysis,and offers a generalizable,facet engineeringbased strategy for improving the performance of a variety of electrocatalysts important for renewable energy conversion.展开更多
Functional failure mode of commercial deep sub-micron static random access memory（SRAM） induced by total dose irradiation is experimentally analyzed and verified by circuit simulation. We extensively characterize th...Functional failure mode of commercial deep sub-micron static random access memory（SRAM） induced by total dose irradiation is experimentally analyzed and verified by circuit simulation. We extensively characterize the functional failure mode of the device by testing its electrical parameters and function with test patterns covering different functional failure modes. Experimental results reveal that the functional failure mode of the device is a temporary function interruption caused by peripheral circuits being sensitive to the standby current rising. By including radiation-induced threshold shift and off-state leakage current in memory cell transistors, we simulate the influence of radiation on the functionality of the memory cell. Simulation results reveal that the memory cell is tolerant to irradiation due to its high stability, which agrees with our experimental result.展开更多
A novel pyridine derivate, 9-hexyl-3-（（pyridin-4-yl）vinyl）-9H-carbazole, was synthesized and characterized by 1H NMR spectra and X-ray diffraction analysis. The complex crystallizes in monoclinic, space group P21/...A novel pyridine derivate, 9-hexyl-3-（（pyridin-4-yl）vinyl）-9H-carbazole, was synthesized and characterized by 1H NMR spectra and X-ray diffraction analysis. The complex crystallizes in monoclinic, space group P21/n with a = 9.111（5）, b = 8.239（5）, c = 26.835（5） A, β = 95.340（5）°, Mr = 354.48, V = 2005.6（17） A3, Z = 4, Dc = 1.174 g/cm3,μ = 0.068 mm^-1, F（000） = 760, R = 0.0565 and wR = 0.1550 for 12635 observed reflections （I 〉 2σ（I））. Density functional theory （DFT） calculations were carried out to interpret its UV-Vis spectra, and the results are in agreement with the available experiments.展开更多
Heteroatom-doped carbon-based transition-metal single-atom catalysts(SACs) are promising electrocatalysts for oxygen reduction reaction(ORR). Herein, with the aid of hierarchically porous silica as hard template, a fa...Heteroatom-doped carbon-based transition-metal single-atom catalysts(SACs) are promising electrocatalysts for oxygen reduction reaction(ORR). Herein, with the aid of hierarchically porous silica as hard template, a facile and general melting perfusion and mesopore-confined pyrolysis method was reported to prepare single-atomic Fe/N–S-doped carbon catalyst(FeNx/NC-S) with hierarchically porous structure and well-defined morphology. The FeNx/NC-S exhibited excellent ORR activity with a half-wave potential(E_(1/2)) of 0.92 V, and a lower overpotential of 320 mV at a current density of 10 mA cm^(-2)for OER under alkaline condition. The remarkable electrocatalysis performance can be attributed to the hierarchically porous carbon nanospheres with S doping and high content of Fe-Nx sites(up to 3.7 wt% of Fe), resulting from the nano-confinement effect of the hierarchically porous silica spheres(NKM-5) during the pyrolysis process. The rechargeable Zn-air battery with FeNx/NC-S as a cathode catalyst demonstrated a superior power density of 194.5 mW cm-2charge–discharge stability. This work highlights a new avenue to design advanced SACs for efficient sustainable energy storage and conversion.展开更多
基金support by the National Natural Science Foundation of China(51802269,21773138)Fundamental Research Funds for the Central Universities(XDJK2019AA002)+1 种基金the Venture&Innovation Support Program for Chongqing Overseas Returnees(cx2018027)the innovation platform for academicians of Hainan province.
文摘Using porous carbon hosts in cathodes of Li-S cells can disperse S actives and offset their poor electrical conductivity.However,such reservoirs would in turn absorb excess electrolyte solvents to S-unfilled regions,causing the electrolyte overconsumption,specific energy decline,and even safety hazards for battery devices.To build better cathodes,we propose to substitute carbons by In-doped SnO_(2)(ITO)nano ceramics that own three-in-one functionalities:1)using conductive ITO enables minimizing the total carbon content to an extremely low mass ratio(~3%)in cathodes,elevating the electrode tap density and averting the electrolyte overuse;2)polar ITO nanoclusters can serve as robust anchors toward Li polysulfide(LiPS)by electrostatic adsorption or chemical bond interactions;3)they offer catalysis centers for liquid–solid phase conversions of S-based actives.Also,such ceramics are intrinsically nonflammable,preventing S cathodes away from thermal runaway or explosion.These merits entail our configured cathodes with high tap density(1.54 g cm^(−3)),less electrolyte usage,good security for flame retardance,and decent Li-storage behaviors.With lean and LiNO_(3)-free electrolyte,packed full cells exhibit excellent redox kinetics,suppressed LiPS shuttling,and excellent cyclability.This may trigger great research enthusiasm in rational design of low-carbon and safer S cathodes.
基金financial support from National Key R&D Program of China(MoST,2020YFA0711500)the National Natural Science Foundation of China(NSFC,21875114),(NSFC,52303348)+1 种基金111 Project(B18030)“The Fundamental Research Funds for the Central Universities”,Nankai University.
文摘Two-dimensional carbon-based materials have shown promising electromagnetic wave absorption capabilities in mid-and high-frequency ranges,but face challenges in low-frequency absorption due to limited control over polarization response mecha-nisms and ambiguous resonance behavior.In this study,we pro-pose a novel approach to enhance absorption efficiency in aligned three-dimensional(3D)MXene/CNF(cellulose nanofibers)cavities by modifying polarization properties and manipulating resonance response in the 3D MXene architecture.This controlled polarization mechanism results in a significant shift of the main absorption region from the X-band to the S-band,leading to a remarkable reflection loss value of-47.9 dB in the low-frequency range.Furthermore,our findings revealed the importance of the oriented electromagnetic coupling in influencing electromagnetic response and microwave absorption properties.The present study inspired us to develop a generic strategy for low-frequency tuned absorption in the absence of magnetic element participation,while orientation-induced polarization and the derived magnetic resonance coupling are the key controlling factors of the method.
基金Funded by the Natural Sciences Foundation of China(No.51808025)the Pyramid Talent Training Project of BUCEA(No.JDYC20200329)。
文摘To explore the distribution of and the mechanical properties(compressive strength)of the hardened body of alkali slag-fly ash cementitious materials,this study was conducted by using the XRD,FTIR,SEM/EDS,and other test methods in three conditions:airtight drying(AD),airtight immersion(AI),and airtight soaking(AS).The 1D distribution law of free of hardened body under standard curing conditions was explored.The experimental results show that under standard curing conditions,the 1D distribution of within 0d-3 d shows a∨-shaped distribution,within 3-7 d show a∧-shaped distribution,and within 7-28 d tends to be balanced.The test results of leaching rate show that the free was the most stable under AD conditions and the hardened body bound the most by XRD,FTIR and SEM/EDS.And the compressive strength of the hardened body was the highest.The compressive strength of 28th reached 95.9 MPa.The definite distribution of provides an important reference for the strength development and durability evaluation of the hardened body of alkaliexcited cementitious materials.
基金supported by the National Natural Science Foundation of China(52374301 and 22279030)the Fundamental Research Funds for the Central Universities(N2223037)+1 种基金Hebei Key Laboratory of Dielectric and Electrolyte Functional Material,Northeastern University at Qinhuangdao(HKDEFM2021201)the Performance subsidy fund for the Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(22567627H)。
文摘The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple one-step pyrolysis strategy.The experimental results and density functional theory(DFT)calculation show that the formation of FeCo alloy is conducive to promoting electron transfer,and the introduction of S atom can enhance the interaction between FeCo alloy and carbon substrate,thus inhibiting the migration and agglomeration of particles on the surface of carbon material.The FeCo/SNC catalysts show outstanding performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).FeCo/S-NC shows a high half-wave potential(E_(1/2)=0.8823 V)for ORR and a low overpotential at 10 mA cm^(-2)(E_(j=10)=299 mV)for OER.In addition,compared with Pt/C+RuO_(2) assembled Zn-air battery(ZAB),the FeCo/S-NC assembled ZAB exhibits a larger power density(198.8 mW cm^(-2)),a higher specific capacity(786.1 mA h g_(zn)~(-1)),and ultra-stable cycle performance.These results confirm that the optimized composition and the interfacial interaction between catalyst and carbon substrate synergistically enhance the electrochemical performance.
基金funded by the National Key Research and Development Project,Intergovernmental International Science and Technology Innovation Cooperation Key Project(No.2018YFE0108800)National Natural Science Foundation of China(No.22278115)Heilongjiang Province Natural Science Foundation(No.YQ2021B010).
文摘The development of highly effective metal-zeolite bifunctional catalysts for the hydroisomerization of n-alkanes is a paramount strategy to produce second-generation biofuels with high quality.In this study,polyhexamethylene biguanide hydrochloride(PHMB)is precisely added to the initial gel to synthesize nanosized ZSM-23 zeolites(Z23-x PH).Due to orientation adsorption and steric hindrance effects of PHMB,each sample of Z23-x PH demonstrates enhanced mesoporosity in comparison with the conventional Z23-C zeolite.Furthermore,the Bronsted acid density of the Z23-x PH samples is also signifi cantly reduced due to a reduction in the distribution of framework Al at T2-T5 sites.The corresponding Pd/23-C and Pd/Z23-x PH bifunctional catalysts with 0.5 wt%Pd loading for n-hexadecane hydroisomerization are prepared by incorporating ZSM-23 zeolites as acid supports.According to the catalytic test results,the suitable addition of PHMB can effectively promote the iso-hexadecane yield.The Pd/Z23-2PH catalyst with an n_(PHMB)/n(_Si)molar ratio of 0.002 demonstrates the highest maximum iso-hexadecane yield of 74.1%at an n-hexadecane conversion of 88.3%.Therefore,the employment of PHMB has provided a simple route for the development of highly effective Pd/ZSM-23 catalysts for n-alkane hydroisomerization.
文摘Isosorbide is a novel bio-based material derived as a secondary dehydration product of sorbitol.This work focuses on the kinetics of sulfuric acid-catalyzed dehydration of sorbitol under conditions of nonconstant volume.Herein,the effects of stirring rate,catalyst dosage,reaction temperature,and reaction time on the dehydration reaction of sorbitol were investigated.The yield of isosorbide up to 77.13%was obtained after 1.5 h of reaction time under conditions of 2 kPa,1.0%(mass)catalyst dosage,and 413.15 K.Based on the sorbitol dehydration reaction mechanism and a simplified reaction network,a kinetic model was developed in this work.A good agreement was accomplished between kinetic modeling and experiments between 393.15 and 423.15 K.The fitting results indicate that side reactions with higher activation energies are more affected by reaction temperatures,and the main side reaction that influences the selectivity of isosorbide is the oligomerization reaction among the primary dehydration products of sorbitol.The model fitting of the catalyst amounts effect shows that the effective concentration of sulfuric acid would be reduced with the increase of dosage due to the molecular agglomeration effect.Hopefully,the kinetic experiments and modeling results obtained in this work will be helpful to the design and optimization of the industrial sorbitol dehydration process.
基金National Natural Science Foundation of China,Grant/Award Numbers:92163126,52293380,52293383Fundamental Research Funds for the Central Universities,Grant/Award Numbers:63241614,63233051Beijing National Laboratory for Molecular Sciences,Grant/Award Number:BNLMS202308。
文摘The exploration of antibiotic-independent phototherapy strategies for the treatment of bacterial biofilm infections has gained significant attention.However,efficient eradication of bacterial biofilms remains a challenge.Herein,a self-regulated pho-totheranostic nanosystem with single wavelength-triggered photothermal therapy(PTT)/photodynamic therapy(PDT)transformation and oxygen supply for multi-modal synergistic therapy of bacterial biofilm infections is presented.This approach combines a eutectic mixture of natural phase-change materials(PCMs)and an aggregation-induced emission(AIE)phototheranostic agent TPA-ICN to form col-loidally stable nanopartcicles(i.e.AIE@PCM NPs).The reversible solid-liquid phase transition of PCMs facilitates the adaptive regulation of the aggregation states of TPA-ICN,enabling a switch between the energy dissipation pathways for enhanced PDT in solid PCMs or enhanced PTT in liquid PCMs.Addition-ally,oxygen-carrying thermoresponsive nanoparticles are also introduced to alleviate the hypoxic microenvironment of biofilms by releasing oxygen upon heating by AIE@PCM NPs with enhanced PTT.The nanosystem exhibits outstanding therapeu-tic efficacy against bacterial biofilms both in vitro and in vivo,with an antibacterial efficiency of 99.99%.This study utilizes a self-regulated theranostic nanoplatform with adaptive PTT/PDT transformation via the phase transition of PCMs and heat-triggered oxygen release,holding great promise in the safe and efficient treatment of bacterial biofilm infections.
基金National Natural Science Foundation of China,Grant/Award Numbers:92163126,52293380,52293383Beijing National Laboratory for Molecular Sciences,Grant/Award Number:BNLMS202308Fundamental Research Funds for the Central Universities,Grant/Award Numbers:63223030,63223017。
文摘Controlling the growth of bacterial biofilms in a specific pattern greatly enhances the study of cell-to-cell interactions and paves the way for expanding their biolog-ical applications.However,the development of simple,cost-effective,and highly resolved biopatterning approaches remains a persistent challenge.Herein,a pio-neering photodynamic biopatterning technique for the creation of living bacterial biofilms with customized geometries at high resolutions is presented.First of all,an outstanding aggregation-induced emission photosensitizer is synthesized to enable efficient photodynamic bacterial killing at a low concentration.By combining with custom-designed photomasks featuring both opaque and transparent patterns,the viability of photosensitizer-coated bacteria is successfully manipulated by control-ling the degree of light transmittance.This process leads to the formation of living bacterial biofilms with specific patterns replicated from the photomask.Such an innovative strategy can be employed to generate living bacterial biofilms composed of either mono-or multispecies,with a spatial resolution of approximately 24µm.Furthermore,its potential applications in information storage/encryption and antibi-otic screening are explored.This study provides an alternative way to understand and investigate the intricate interactions among bacteria within 3D biofilms,hold-ing great promise in the controlled fabrication of dynamic biological systems for advanced applications.
基金Project supported financially by the Program for the Development of Science and Technology of Jilin Province,China(Grant Nos.YDZJ202301ZYTS382,YDZJ202201ZYTS316,and 20230101285JC)the National Natural Science Foundation of China(Grant No.11904128)+1 种基金the Program for Science and Technology of Education Department of Jilin Province,China(Grant Nos.JJKH20220438KJ and JJKH20220423KJ)the Program for the Jilin Provincial Development and Reform Commission Project(Grant No.2022C040-6)。
文摘The high-pressure structure and elastic properties of calcium azide(Ca(N_(3))_(2))were investigated using in-situ highpressure x-ray diffraction and Raman scattering up to 54 GPa and 19 GPa,respectively.The compressibility of Ca(N_(3))_(2)changed as the pressure increased,and no phase transition occurred within the pressure from ambient pressure up to 54 GPa.The measured zero-pressure bulk modulus of Ca(N_(3))_(2)is higher than that of other alkali metal azides,due to differences in the ionic character of their metal-azide bonds.Using CASTEP,all vibration modes of Ca(N_(3))_(2)were accurately identified in the vibrational spectrum at ambient pressure.In the high-pressure vibration study,several external modes(ext.)and internal bending modes(ν_(2))of azide anions(N_(3)^(-))softened up to~7 GPa and then hardened beyond that pressure.This evidence is consistent with the variation observed in the F_(E)–f_(E)data analyzed from the XRD result,where the slope of the curve changes at 7.1 GPa.The main behaviors under pressure are the alternating compression,rotation,and bending of N_(3)^(-)ions.The bending behavior makes the structure of Ca(N_(3))_(2)more stable under pressure.
基金supported by the National Natural Science Foundation of China(No.20874049)
文摘Monodisperse hollow polymer microspheres having various functional groups on the shell-layer, such as carboxylic acid, pyridyl and amide, were prepared by two-stage distillation precipitation polymerization in neat acetonitrile in the absence of any stabilizer or additive, during which monodisperse poly（methacrylic acid） （PMAA） afforded from the first-stage polymerization was utilized as the seeds for the second-stage polymerization. The shell layer with different functional groups was formed during the second-stage copolymerization of either divinylbenzene （DVB） or ethyleneglycol dimethacrylate （EGDMA） as crosslinker and the functional comonomers, in which the hydrogen-bonding interaction between the carboxylic acid group of PMAA core and the functional groups of the corresponding comonomers, including carboxylic acid, amide and pyridyl, played an essential role for the formation of monodisperse core-shell functional microspheres. The hollow polymer microspheres were then developed after the subsequent removal of PMAA cores by dissolution in ethanol under basic condition. Transmission electron microscopy （TEM） and scanning electron microscopy （SEM） were used to determine the morphology of the resultant PMAA core, functional core-shell microspheres and the corresponding hollow polymer microspheres with different functional groups. FT-IR spectra confirmed the successful incorporation of the various functional groups on the shell layer of the hollow polymer microspheres.
基金supported by the National Natural Science Foundation of China(U1401245,91622119)the Program for Innovative Research Team in Chinese Universities(IRT1237)+1 种基金the Research Project of Chinese Ministry of Education(213011A)the Science Foundation for Excellent Youth of Harbin City of China(2014RFYXJ002)~~
文摘One of the most general methods to enhance the separation of photogenerated carriers for g‐C3N4is to construct a suitable heterojunctional composite,according to the principle of matching energy levels.The interface contact in the fabricated nanocomposite greatly influences the charge transfer and separation so as to determine the final photocatalytic activities.However,the role of interface contact is often neglected,and is rarely reported to date.Hence,it is possible to further enhance the photocatalytic activity of g‐C3N4‐based nanocomposite by improving the interfacial connection.Herein,phosphate-oxygen(P-O)bridged TiO2/g‐C3N4nanocomposites were successfully synthesized using a simple wet chemical method,and the effects of the P-O functional bridges on the photogenerated charge separation and photocatalytic activity for pollutant degradation and CO2reduction were investigated.The photocatalytic activity of g‐C3N4was greatly improved upon coupling with an appropriate amount of nanocrystalline TiO2,especially with P-O bridged TiO2.Atmosphere‐controlled steady‐state surface photovoltage spectroscopy and photoluminescence spectroscopy analyses revealed clearly the enhancement of photogenerated charge separation of g‐C3N4upon coupling with the P-O bridged TiO2,resulting from the built P-O bridges between TiO2and g‐C3N4so as to promote effective transfer of excited electrons from g‐C3N4to TiO2.This enhancement was responsible for the improved photoactivity of the P-O bridged TiO2/g‐C3N4nanocomposite,which exhibited three‐time photocatalytic activity enhancement for2,4‐dichlorophenol degradation and CO2reduction compared with bare g‐C3N4.Furthermore,radical‐trapping experiments revealed that the·OH species formed as hole‐modulated direct intermediates dominated the photocatalytic degradation of2,4‐dichlorophenol.This work provides a feasible strategy for the design and synthesis of high‐performance g‐C3N4‐based nanocomposite photocatalysts for pollutant degradation and CO2reduction.
基金supported by the National Natural Science Foundation of China(U1960107)the“333”Talent Project of Hebei Province(A202005018)+1 种基金the Fundamental Research Funds for the Central Universities(N2123034 and N2123001)Hebei Key Laboratory of Dielectric and Electrolyte Functional Material,Northeastern University at Qinhuangdao(HKDEFM2021201)。
文摘Li_(5)Cr_(7)Ti_(6)O_(25) is regarded as a promising anode material for Li-ion batteries(LIBs)because of its low cost and high theoretical capacity.However,the inherently poor conductivity significantly limits the enhancement of its rate capability and cycling stability,especially at high current densities.In this work,we construct one-dimensional Li_(5)Cr_(7)Ti_(6)O_(25)/C nanofibers by electrospinning method to enhance the kinetic,which realizes high cycling stability.Carbon coating enhances the structure stability,insertion/extraction reversibility of Li-ions and electrochemical reaction activity,and facilitates the transfer of Li-ions.Benefited from the unique architecture and component,the Li_(5)Cr_(7)Ti_(6)O_(25)/C(6.6 wt%)nanofiber shows an excellent rate capability with a reversible de-lithiation capacity of 370.8,290.6,269.2,254.3 and 244.9 m Ah g^(-1) at 200,300,500,800 and 1000 m A g^(-1),respectively.Even at a higher current density of 1 A g^(-1),Li_(5)Cr_(7)Ti_(6)O_(25)/C(6.6 wt%)nanofiber shows high cycling stability with an initial de-lithiation capacity of 237.8 m Ah g^(-1) and a capacity retention rate of about 84%after 500 cycles.The density functional theory calculation result confirms that the introduction of carbon on the surface of Li_(5)Cr_(7)Ti_(6)O_(25) changes the total density of states of Li_(5)Cr_(7)Ti_(6)O_(25),and thus improves electronic conductivity of the composite,resulting in a good electrochemical performance of Li_(5)Cr_(7)Ti_(6)O_(25)/C nanofibers.Li_(5)Cr_(7)Ti_(6)O_(25)/C nanofibers indicate a great potential as an anode material for the next generation of high-performance LIBs.
基金Project supported by the National Natural Science Foundation of China(Grant No.11227902)as part of NSFC ME2 beamline project,Science and Technology Commission of Shanghai Municipality,China(Grant No.14520722100)the National Natural Science Foundation of China(Grant Nos.11905283 and U1632269)
文摘A new photon-in/photon-out endstation at beamline 02B02 of the Shanghai Synchrotron Radiation Facility for studying the electronic structure of energy materials has been constructed and fully opened to users.The endstation has the capability to perform soft x-ray absorption spectroscopy in total electron yield and total fluorescence yield modes simultaneously.The photon energy ranges from 40 eV to 2000 eV covering the K-edge of most low Z-elements and the L-edge of 3d transition-metals.The new self-designed channeltron detector allows us to achieve good fluorescence signals at the low photon flux.In addition,we synchronously collect the signals of a standard reference sample and a gold mesh on the upstream to calibrate the photon energy and monitor the beam fluctuation,respectively.In order to cross the pressure gap,in situ gas and liquid cells for soft x-ray absorption spectroscopy are developed to study the samples under realistic working conditions.
基金Project supported by the National Fund for Distinguished Young Scholars （Grant No 59925205）, the Basic Research Program of Shanghai （Grant No 02DJ14069）, and the National Natural Science Foundation of China （Grant No 10305018）.
文摘The hardening of the buried oxide （BOX） layer of separation by implanted oxygen （SIMOX） silicon-on-insulator （SOI） wafers against total-dose irradiation was investigated by implanting ions into the BOX layers. The tolerance to total-dose irradiation of the BOX layers was characterized by the comparison of the transfer characteristics of SOI NMOS transistors before and after irradiation to a total dose of 2.7 Mrad（SiO2）. The experimental results show that the implantation of silicon ions into the BOX layer can improve the tolerance of the BOX layers to total-dose irradiation. The investigation of the mechanism of the improvement suggests that the deep electron traps introduced by silicon implantation play an important role in the remarkable improvement in radiation hardness of SIMOX SOI wafers.
基金Supported by the National Natural Science Foundation of China(Nos.20676027 and 21076066)the Postdoctoral Foundation of Heilongjiang Province,China(No.LBH-Q07111)
文摘The electrocatalytic oxidation of nitric oxide（NO） at a glass carbon electrode（GC） modified with functionalized single-walled carbon nanotubes（SWCNTs） was investigated by cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）.It was found that the SWCNT modified electrode could speed greatly up the electron transfer rate compared with the bare GC electrode.After the SWCNT was treated with alkali or mixed acids,the reaction rate and activation energy of NO electrooxidation were changed to different extent.Chemical modification of the SWCNT surface is one of the most powerful methods to change the sensitivity of NO electrooxidation reaction.The modified electrode with SWCNT obtained by the firstly alkali treatment and then the mixed acids treatment was the best one for NO electrooxidation,the result of CV was also confirmed by that of EIS.The anodic processes of NO were recognized more clearly by exploring the reaction mechanism of NO electrooxidation at the SWCNT modified electrode.
文摘In the search of alternative resources to make commodity chemicals and transportation fuels for a low carbon future,lignocellulosic biomass with over 180-billion-ton annual production rate has been identified as a promising feedstock.This review focuses on the state-of-the-art catalytic transformation of lignocellulosic biomass into value-added chemicals and fuels.Following a brief introduction on the structure,major resources and pretreatment methods of lignocellulosic biomass,the catalytic conversion of three main components,i.e.,cellulose,hemicellulose and lignin,into various compounds are comprehensively discussed.Either in separate steps or in one-pot,cellulose and hemicellulose are hydrolyzed into sugars and upgraded into oxygen-containing chemicals such as 5-HMF,furfural,polyols,and organic acids,or even nitrogen-containing chemicals such as amino acids.On the other hand,lignin is first depolymerized into phenols,catechols,guaiacols,aldehydes and ketones,and then further transformed into hydrocarbon fuels,bioplastic precursors and bioactive compounds.The review then introduces the transformations of whole biomass via catalytic gasification,catalytic pyrolysis,as well as emerging strategies.Finally,opportunities,challenges and prospective of woody biomass valorization are highlighted.
基金supported by the Guangdong Provincial Natural Science Foundation,China(2021A1515012330)the National Natural Science Foundation of China(11975102)+2 种基金the State Key Laboratory of Pulp and Paper Engineering(2022PY03)the Guangdong Pearl River Talent Program,China(2017GC010281)supported by ME2 project under contract from the National Natural Science Foundation of China(11227902)。
文摘Electrochemical reduction of nitrate,a common pollutant in aquatic environment,to valuable ammonia(NO3-RR) using renewably-sourced electricity has attracted widespread interests,with past efforts mainly focused on designing electrocatalysts with high activity and selectivity.The detailed correlation between catalyst properties and NO3-RR kinetics,nevertheless,is still not fully understood.In this work,we modulate the surface oxygen species of Cu_(2)O via facet engineering,and systematically study the impact of these oxygen species on the NO_(3)^(-)RR activity.Combining advanced spectroscopic techniques,densi ty fu n ctional theory calculations and molecular dynamics simulations,we find that while oxygen vacancies on Cu_(2)O(111) surface promote the adsorption of reactants and reaction intermediates,hydroxyl groups effectively inhibit the side reaction of hydrogen evolution and facilitate the hydrogenation process of NO3-RR.These two effects work in concert to render Cu_(2)O(111) facet the highest NO3-RR activity relative to those from other facets.Our study provides critical insights into the synergistic effect of exposed facets and surface oxygen species on heterogeneous catalysis,and offers a generalizable,facet engineeringbased strategy for improving the performance of a variety of electrocatalysts important for renewable energy conversion.
文摘Functional failure mode of commercial deep sub-micron static random access memory（SRAM） induced by total dose irradiation is experimentally analyzed and verified by circuit simulation. We extensively characterize the functional failure mode of the device by testing its electrical parameters and function with test patterns covering different functional failure modes. Experimental results reveal that the functional failure mode of the device is a temporary function interruption caused by peripheral circuits being sensitive to the standby current rising. By including radiation-induced threshold shift and off-state leakage current in memory cell transistors, we simulate the influence of radiation on the functionality of the memory cell. Simulation results reveal that the memory cell is tolerant to irradiation due to its high stability, which agrees with our experimental result.
基金supported by the National Natural Science Foundation of China (50532030,20771001,50703001)the Foundation for Scientific Innovation Team of Anhui Province (2006KJ007TD)Doctoral Program Foundation of Ministry of Education (20050357001)
文摘A novel pyridine derivate, 9-hexyl-3-（（pyridin-4-yl）vinyl）-9H-carbazole, was synthesized and characterized by 1H NMR spectra and X-ray diffraction analysis. The complex crystallizes in monoclinic, space group P21/n with a = 9.111（5）, b = 8.239（5）, c = 26.835（5） A, β = 95.340（5）°, Mr = 354.48, V = 2005.6（17） A3, Z = 4, Dc = 1.174 g/cm3,μ = 0.068 mm^-1, F（000） = 760, R = 0.0565 and wR = 0.1550 for 12635 observed reflections （I 〉 2σ（I））. Density functional theory （DFT） calculations were carried out to interpret its UV-Vis spectra, and the results are in agreement with the available experiments.
基金supported by National Natural Science Foundation of China (21773128)。
文摘Heteroatom-doped carbon-based transition-metal single-atom catalysts(SACs) are promising electrocatalysts for oxygen reduction reaction(ORR). Herein, with the aid of hierarchically porous silica as hard template, a facile and general melting perfusion and mesopore-confined pyrolysis method was reported to prepare single-atomic Fe/N–S-doped carbon catalyst(FeNx/NC-S) with hierarchically porous structure and well-defined morphology. The FeNx/NC-S exhibited excellent ORR activity with a half-wave potential(E_(1/2)) of 0.92 V, and a lower overpotential of 320 mV at a current density of 10 mA cm^(-2)for OER under alkaline condition. The remarkable electrocatalysis performance can be attributed to the hierarchically porous carbon nanospheres with S doping and high content of Fe-Nx sites(up to 3.7 wt% of Fe), resulting from the nano-confinement effect of the hierarchically porous silica spheres(NKM-5) during the pyrolysis process. The rechargeable Zn-air battery with FeNx/NC-S as a cathode catalyst demonstrated a superior power density of 194.5 mW cm-2charge–discharge stability. This work highlights a new avenue to design advanced SACs for efficient sustainable energy storage and conversion.
