摘要：局部电荷的强离域和强偶极矩是影响共价有机框架(COFs)基光催化剂催化析氢性能的两个关键因素.然而,基于精确的调控结构模型来系统研究这种构效关系的报告相对较少.本研究提出了一种新的策略,通过合理的设计,制备了三种三芴酮基COFs,通过在分子水平上调控单体的结构和偶极来提高局部电荷离域指数.我们重点研究这三种三芴酮基COF的局部电荷离域与光催化性能之间的构效关系.在不同三芴酮基COF中,1,3,5-三(对甲酰基苯基)苯基COF(TeTpb-COF)展现出21.6 mmol g^(-1)h^(-1)的最高析氢速率,与2,4,6-三(4-醛基苯基)-1,3,5-三嗪基COF(TeTt-COF,0.2mmol g^(-1)h^(-1))相比,光催化析氢性能提高了108倍.这种性能的增强可归因于其强大的分子内置电场提高了供体-受体嵌段单元中光生电荷的有效分离效率.这项工作证实了调整构建块可以极大增强三芴酮基COFs中的局部偶极矩,从而显著改善光催化析氢性能.构建模块的调控策略为创建高效的新型COF基光催化析氢平台提供了新机会.

摘要：The separator is a key component of sodium-ion battery,which greatly affects the electrochemical performances and safety characteristics of the *** glass fiber separator cannot meet the requirements of large-scale application because of high cost and poor mechanical ***,the novel composite separators are prepared by a simple slurry sieving process using glass fiber separator scraps and ordinary qualitative filter paper as raw *** the composite mass ratio is 1:1,the composite separator has excellent comprehensive properties,including tensile strength of 15.8 MPa,porosity of 74.3%,ionic conductivity of 1.57×10^(-3)S·cm^(-1)and thermal stability at 210℃.The assembled sodium-ion battery shows superior cycling performance(capacity retention of 94.1%after 500 cycles at 1C)and rate capacity(retention rate of 87.3%at 10C),and it maintains fine interface *** above results provide some new ideas for the separator design of high-performance and low-cost sodium-ion batteries.

摘要：The multiple quantum transitions within d-band correlation oxides such as rare-earth nickelates(RENiO_(3))triggered by critical temperatures and/or hydrogenation opened up a new paradigm for correlated electronics applications,*** electric field sensor,bio-sensor,and neuron synapse logical ***,these applications are obstructed by the present ineffectiveness in the thin film growth of the metastable RENiO_(3)with flexibly adjustable rare-earth compositions and electronic ***,we demonstrate a metal-organic decompositions(MOD)approach that can effectively grow metastable RENiO_(3)covering a large variety of the rare-earth composition without introducing any vacuum *** the previous chemical growths for RENiO_(3)relying on strict interfacial coherency that limit the film thickness,the MOD growth using reactive isooctanoate percussors is tolerant to lattice defects and therefore achieves comparable film thickness to vacuum *** indicated by positron annihilation spectroscopy,the RENiO_(3)grown by MOD exhibit large amount of lattice defects that improves their hydrogen incorporation amount and electron transfers,as demonstrated by the resonant nuclear reaction analysis and near edge X-ray absorption fine structure *** effectively enlarges the magnitude in the resistance regulations in particular for RENiO_(3)with lighter RE,shedding a light on the extrinsic regulation of the hydrogen induced quantum transitions for correlated oxides semiconductors kinetically via defect engineering.

摘要：Rational designs of electrocatalytic active sites and architectures are of great importance to develop cost-efficient non-noble metal electrocatalysts towards efficient oxygen reduction reaction(ORR)for high-performance energy conversion and storage *** this work,active amorphous Fe-based nanoclusters(Fe NC)are elaborately embedded at the inner surface of balloonlike N-doped hollow carbon(Fe NC/Csphere)as an efficient ORR electrocatalyst with an ultrathin wall of about 10 *** evaluated for electrochemical performance,Fe NC/Csphere exhibits decent ORR activity with a diffusionlimited current density of~5.0 mA/cm^(2)and a half-wave potential of~0.81 V in alkaline solution,which is comparable with commercial Pt/C and superior to Fe nanoparticles supported on carbon sheet(Fe NP/C sheet)*** electrochemical analyses combined with electronic structure characterizations reveal that robust Fe-N interactions in amorphous Fe nanoclusters are helpful for the adsorption of surface oxygen-relative species,and the strong support effect of N-doped hollow carbon is benefitial for accelerating the interfacial electron transfer,which jointly contributes to improve ORR kinetics for Fe NC/Csphere.

摘要：Lightweight and efficient carbon-based microwave absorbents are significant in addressing the increasing severity of electromagnetic *** this study,hierarchical NiO/Ni nanosheets with a tuneable phase and morphology supported on a carbon fiber substrate(CF@NiO/Ni)were fabricated using a hydrothermal approach and post-annealing *** the annealing temperature increases,more metallic Ni is formed,and an apparent porosity appears on the sheet *** from the advantages of a three-dimensional(3D)conducting network,hierarchical porous structure,reinforced dipole/interface polarization,multiple scattering,and good impedance matching,the CF@NiO/Ni-500 composite exhibits an excellent microwave absorption performance even at a filling rate of only 3wt%.Specifically,its minimal reflection loss is-43.92 dB,and the qualified bandwidth is up to 5.64 *** addition,the low radar cross-section area of the CF@NiO/Ni composite coating confirms its strong ability to suppress electromagnetic wave *** expect that this work could contribute to a deeper understanding of the phase and morphology evolution in enhancing microwave absorption.

摘要：Emerging quantum dots(QDs)based light-emitting field-effect transistors(QLEFETs)could generate light emission with high color purity and provide facile route to tune optoelectronic properties at a low fabrication *** efforts have been devoted to designing device structure and to understanding the underlying physics,yet the overall performance of QLEFETs remains low due to the charge/exciton loss at the interface and the large band offset of a QD layer with respect to the adjacent carrier transport ***,we report highly efficient QLEFETs with an external quantum efficiency(EQE)of over 20%by employing a dielectric-QDs-dielectric(DQD)sandwich *** DQD structure is used to control the carrier behavior by modulating energy band alignment,thus shifting the exciton recombination zone into the emissive ***,enhanced radiative recombination is achieved by preventing the exciton loss due to presence of surface traps and the luminescence quenching induced by interfacial charge *** DQD sandwiched design presents a new concept to improve the electroluminescence performance of QLEFETs,which can be transferred to other material systems and hence can facilitate exploitation of QDs in a new type of optoelectronic devices.

摘要：Cu-based catalysts are the most promising candidates for electrochemical CO_(2)reduction(CO_(2)RR)to multi-carbon(C_(2))*** the C-C coupling process,the rate-determining step for C_(2)product generation,is an important strategy to improve the production and selectivity of the C_(2)*** this study,we determined that the local electric field can promote the C-C coupling reaction and enhance CO_(2)electroreduction to C_(2)***,finite-element simulations indicated that the high curvature of the Cu nanoneedles results in a large local electric field on their *** functional theory(DFT)calculations proved that a large electric field can promote C-C *** by this prediction,we prepared a series of Cu catalysts with different *** Cu nanoneedles(NNs)exhibited the largest number of curvatures,followed by the Cu nanorods(NRs),and Cu nanoparticles(NPs).The Cu NNs contained the highest concentration of adsorbed K+,which resulted in the highest local electric field on the *** adsorption sensor tests indicated that the Cu NNs exhibited the strongest CO adsorption ability,and in-situ Fourier-transform infrared spectroscopy(FTIR)showed the strongest*COCO and*CO signals for the Cu *** experimental results demonstrate that high-curvature nanoneedles can induce a large local electric field,thus promoting C-C *** a result,the Cu NNs show a maximum FEC_(2)of 44%for CO_(2)RR at a low potential(-0.6 V ***),which is approximately 2.2 times that of the Cu *** work provides an effective strategy for enhancing the production of multi-carbon products during CO_(2)RR.

摘要：Stacking nanoscale-building blocks into onedimensional(1D)assemblies with collective physical properties is a frontier in designing ***,the formation of 1D arrays using weak magnetic fields and an in-depth understanding of their magnetic properties remain ***,low-dimensional assemblies of iron oxide nanocubes with a disordered arrangement are fabricated at the diethylene-glycol/air interface in the presence of assembly fields(0/1/3/5/30/50 mT).Ring-shaped assemblies gradually transform as the assembly field increases from 0 to 50 mT,first to a porous network consisting of elongated assemblies and then to an aligned array of filaments,in which the aligned filaments are formed when the assembly field is≥3 mT and duration t>14 ***-glass characteristics and static(dynamic)anisotropy factors~2(3)are achieved by tuning the strength of the assembly *** the presence of a relatively weak assembly field,the interplay between dipolar interactions and disorder with respect to magnetic easy axis alignment leads to spin-glass *** alignment of the magnetic easy axes and the strength of the dipolar interactions increase with increasing assembly field,resulting in the disappearance of spin-glass characteristics and enhancement of the magnetic *** study presents a strategy for obtaining magnetic assemblies with spin-glass behavior and controllable anisotropy while shedding light on the magnetic interactions of low-dimensional assemblies.

摘要：Negative thermal expansion(NTE),as an abnormal physical behavior,has been followed by scientists’attention over the past 30 years,due to its fascinating physical mechanisms and the prospect of high-precision thermal expansion control[1-5].Although some NTE materials(alloys[6],cyanides[7],fluorides[8-10],nitrides[11],oxides[12,13],MOFs[14-16],etc.)have been found,their number and variety are still very small,limiting their *** and designing new NTE materials is an important and challenging topic for the development of the field of *** have been continually reviewing and summarizing obtained results to look to the future of NTE[17-23].

摘要：The need for reducing the wear in mechanical parts used in the industry makes self-lubricant films one of the sustainable solutions to achieve long-term protection under different environmental *** purpose of this work is to study the influence of C additions on the tribological behavior of a magnetron-sputtered TiN film in air,water,and *** results show that the addition of C into the TiN binary film induced a new amorphous phase,and the films exhibited a dual phase of fcc(face-centered cubic)-TiN and amorphous *** antifriction and wear-resistance properties were enhanced in air and water by adding 19.1at%***,a further increase in the C concentration improved anti-frictional properties but also led to higher wear *** the amorphous phase induced microbatteries and accelerated the corrosion of TiN phases in seawater,the negative abrasion state was detected for all Ti-C-N films due to the adhesion of the tribocorrosion debris on the wear track.