查看更多>>摘要：Microbial electrochemical systems are a promising green and sustainable technology that can transform waste into electricity.Improving conversion efficiency and lowering system costs,particularly for elec-trodes,are the primary directions that promote practical application.Cellulose sponges made from wood pulp have been industrially mass-produced in various application scenarios due to their porosity and green sustainability.In this study,the three-dimensional(3D)porous cellulose sponges carbon(CSC)was obtained by directly carbonizing cellulose sponges at different temperatures(600,700,800,900,1000,and 1100 ℃).It has been successfully used as a high-performance anode in microbial fuel cells(MFCs).The carbonization temperature significantly impacted the materials'specific surface area,con-ductivity,and capacitance.The greater the anode material's carbonization temperature,the lower the charge transfer resistance and the higher the maximum power density(CSC-1100,4.1±0.1 W m-2).The CSC-700's maximum power density(3.62±0.11 W m-2)was the highest power density reported to date among lignocellulose-based anodes with relatively low energy consumption.The pleated multilayer porous surface promotes microbial adhesion and can build thicker biofilms with the highest biomass of 2661±117 μg cm-2(CSC-1100)and containing 86％electrogenic bacteria(Geobacter).To investigate the effect of conducting polymers on the material's surface,we introduced polyaniline and polypyrrole.We found that the CSC-1000/PPy bioanodes produced a maximum power density(4.18±0.05 W m-2),slightly higher than of without polypyrrole-modified(CSC-1000,3.99±0.06 W m-2),indicating that the CSCs anode surface had excellent electron transfer efficiency and could achieve the same amount of energy as the polypyrrole surface.This study introduced a promising method for fabricating high-performance anodes using low-cost,industrialized,and sustainable materials.
查看更多>>摘要：The degradation of organic pollutants using semiconductor photocatalysts is a new ecological approach,but the currently available photocatalysts are not very efficient.Herein,in order to obtain efficient visible-light photocatalysts,g-C3N4/β-FeOOH-modified carbon quantum dots(CDs)composite photocat-alysts with Z-Scheme charge transfer mechanism were successfully synthesized.The phase composition and morphology of the composite were characterized by X-ray diffraction(XRD),scanning electron mi-croscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectrophotometry(FT-IR),and X-ray photoelectron spectroscopy(XPS)techniques.Due to the upconversion effect of the CDs,the optical response range of the composite was effectively widened,and the optical utilization rate was improved.The Z-Scheme heterostructure not only improves the light trapping ability,significantly inhibits charge-carrier complexation,and realizes the spatial separation of redox sites,but also ensures that the photocatalyst maintains a suitable valence-conductivity band position and maintains the strong redox reactivity.In addition,CDs have the unique characteristics of electronic storage and transfer,which effectively enhance the quantum separation efficiency of the composite.The photocatalytic efficiency was measured by degrading rhodamine B(RhB)under visible light.The degradation performance was the best when the weight ratio of CDs was 6％,and the RhB solution degradation rate reached 100％in 60 min.The unique structure and reliable mechanism provide a way for the development of advanced photocat-alyst.
查看更多>>摘要：This work concerns the distinguished roles of static aging and strain aging in the creep resistance of a hot-rolled Mg-4Y-3.5Nd alloy.The solution-treated sample is named AS while the peak-aged sample ob-tained from static aging at 220 ℃ is named AA.The strain aging(creep loading)was performed for both AS and AA samples at 220,250 and 280 ℃,respectively.The results showed that the creep resistance of both samples was closely related to the width of precipitate-free zones(PFZs).Under low stress,the dislocation cross-slip was effectively delayed by the precipitates and the existing PFZs widened slowly in the AA sample,leading to its stronger creep resistance compared to the AS sample.Inversely,under high stress,pyramidal<c+a>slip was more frequently activated,which could not be delayed by the coars-ened precipitates.Consequently,the widening rate of PFZs became fast and the creep resistance became weaker in the AA sample.From the above-mentioned results,this work provides a novel guide for using Mg alloys with rare-earth addition.At the temperature range of 220-280 ℃,static aging is positive for creep resistance under low stress,while directly performing strain aging without static aging is recom-mended for creep resistance under high stress.
查看更多>>摘要：The deformation mechanism,microstructure evolution,and precipitation behavior of a Mg-8.9Gd-1.8Y-0.5Zr-0.2Ag(wt.％)alloy multi-directionally forged at three different temperatures were investigated.As the forging temperature increases,the particle-stimulated nucleation(PSN)effect diminishes as the num-ber of dynamic precipitates decreases,pyramidal slip is activated,grain boundary migration accelerates,and continuous dynamic recrystallization(CDRX)dominates.The microstructures varied greatly,although fine-grained structures were formed at all different forging temperatures.Competitive precipitation be-tween dynamic precipitate growth,dislocation-induced precipitation,and homogeneous precipitation was observed after aging treatment.Among them,the medium temperature(748 K)forged and aged alloy ex-hibits the best mechanical performance,with an ultimate tensile strength of 436 MPa,and elongation of 16.3％.The calculation indicates that the mixed precipitation structure containing the β'precipitate band provides a 35％higher strengthening contribution than the typical homogeneously distributed precipi-tates.The formation of precipitation-free zones(PFZs)ensures that aging will not cause a dramatic de-crease in ductility,which provides a reference for the industrial preparation of high-performance wrought Mg-Gd series alloys.
查看更多>>摘要：In traditional Nd-Fe-B-based sintered magnets,the composition,role of each element and microstruc-tures have been extensively investigated globally since they were invented in 1983.However,the effects of boron(B)content and post-sinter annealing(PSA)on the microstructure and magnetic properties have been least studied so far and the relative mechanisms are not yet clear.In this paper,we investigated the influence of B on the magnetic performance and microstructure of Nd-Fe-B sintered magnets origi-nally containing copper(Cu),gallium(Ga)and titanium(Ti).It is shown that the intrinsic coercivity has a substantial increment of 2.86 kOe and the remanence has a slight reduction of 0.16 kGs when B content is reduced from 0.980 wt.％to 0.900 wt.％.Moreover,there is a coercivity increment of 273％and 653％for samples with 0.980 wt.％and 0.900 wt.％B content after PSA,respectively.It is shown that the im-pacts of B content and PSA are significant and their regulation mechanisms are worthwhile to be studied systematically.Furthermore,it is revealed by microstructural analysis that high coercivity of the sample with 0.900 wt.％B after PSA results from the uniform distribution of Ga,Cu,Nd,and the formation of RE6(Fe,M)14(RE=Pr,Nd,M=Cu,Ga)compound in triple junction phases.The dilution of Fe content in grain boundary phases(GB phases)also plays an important role.It is found out that decrease of the re-manence is mainly due to reduction of the matrix phase and c-axis alignment degree.In this study,we explored a new path to develop Nd-Fe-B-based sintered magnets with high comprehensive properties by novel approaches through varying B content,PSA technique and co-adding trace elements.
查看更多>>摘要：High-entropy alloys(HEAs)consisting of CoCrFeNiAITi systems,with a face-centered cubic(FCC)matrix reinforced by ordered L12 precipitates,have demonstrated exceptional strength-ductility combinations.However,the current compositional design of HEAs heavily relies on high Ni and Co contents,compro-mising the balance between properties and cost.Thus,it is crucial to optimize the cost-performance trade-off by fine-tuning the range of Fe,Co,and Ni,while maintaining excellent strength-ductility com-bination.In this study,we propose a novel Fe-based HEA with nanosized precipitates and a heteroge-neous grain distribution,achieving a strength-ductility combination comparable to state-of-the-art Ni-or Co-based HEAs.The alloy benefits from both precipitation hardening and hetero-deformation-induced strengthening attributed to the heterogeneous grain distribution,resulting in excellent yield strength of 1433 MPa,tensile strength of 1599 MPa,and ductility of 22％.The microstructural evolution and its in-fluence on mechanical properties are unraveled with respect to the observation of precipitate-dislocation interaction and hetero-deformation-induced stress(HDI stress)evaluation.This study suggests that the challenge of balancing properties and cost can be addressed through optimized compositional and mi-crostructural design.
查看更多>>摘要：Regulating the local coordination of Fe active center can further improve the oxygen reduction reaction(ORR)performance of Fe-N-C catalyst to meet the practical application requirements of zinc-air batteries(ZABs).Herein,carbon vacancies modified hollow porous catalysts(C-FeZ8@PDA-950)are constructed by microenvironment modulation,achieving the efficient utilization of active sites and optimization of elec-tronic structure.Density functional theory(DFT)calculations confirm that the defective-edge Fe-N4 sites can weaken the adsorption free energy of OH*,and hinder the dissolution of Fe center,significantly accel-erating the ORR process for ZABs.The rechargeable liquid ZABs equipped with C-FeZ8@PDA-950 display high specific capacity(819.95 mAh gZn-1)and excellent long-cycling life(over 500 h).Furthermore,the relevant flexible all-solid-state ZABs also display outstanding folding performance under various bending angles.This work will provide insights into optimizing the electronic structure to improve electrocatalytic performance in the energy conversion and storage area.
查看更多>>摘要：Language barrier is the main cause of disagreement.Sign language,which is a common language in all the worldwide language families,is difficult to be entirely popularized due to the high cost of learning as well as the technical barrier in real-time translation.To solve these problems,here,we constructed a wearable organohydrogel-based electronic skin(e-skin)with fast self-healing,strong adhesion,extraor-dinary anti-freezing and moisturizing properties for sign language recognition under complex environ-ments.The e-skin was obtained by using an acrylic network as the main body,aluminum(Ⅲ)and bay-berry tannin as the crosslinking agent,water/ethylene glycol as the solvent system,and a polyvinyl al-cohol network to optimize the network performance.Using this e-skin,a smart glove was further built,which could carry out the large-scale data collection of common gestures and sign languages.With the help of the deep learning method,specific recognition and translation for various gestures and sign lan-guages could be achieved.The accuracy was 93.5％,showing the ultra-high classification accuracy of a sign language interpreter.In short,by integrating multiple characteristics and combining deep learning technology with hydrogel materials,the e-skin achieved an important breakthrough in human-computer interaction and artificial intelligence,and provided a feasible strategy for solving the dilemma of mutual exclusion between flexible electronic devices and human bodies.
查看更多>>摘要：Structural design and elemental doping are research hotspots for the preparation of lightweight absorbers with high absorption performance and low filling ratio.Herein,a P-doped hydrangea-like layered compos-ite(Co2P/Ni2P@C)encapsulated with Ni-LDH was successfully synthesized by solvothermal method fol-lowed by phosphorization.The defects generated by P doping and the generation of multilayered nonuni-form interfaces enhance the dielectric loss induced by polarization.Simultaneously,the magnetic phos-phides induce magnetic loss and modulate the dielectric properties of the carbon matrix to enhance the conductive loss.The multilayered hollow structure of this composite promotes the scattering and reflec-tion of electromagnetic waves and optimizes the impedance characteristics.As a result,the multilayered hollow Co2P/Ni2P@C composite exhibits an optimum reflection loss value(RL)of-64.6 dB at 15.1 GHz with a thickness of 2 mm and a filler ratio of only 10 wt％.The radar cross-section(RCS)attenuation further demonstrates that the material can dissipate microwave energy in practical applications.Overall,this work provides an effective development strategy for the design of multilayered high-performance electromagnetic wave(EMW)absorbers doped with strongly polarized elements.
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