查看更多>>摘要：Preparation of electromagnetic(EM)wave-absorbing composites by interface engineering has been the main strategy to obtain high-performance absorbers.However,the conventional strategy is tedious and time-consuming,which hinders the scalable synthesis of stable EM wave-absorbing composites.Herein,interface engineering by a redox reaction between transition metal elements in Co-based spinel fer-rites was employed to create EM wave-absorbing composites to solve the above problem.Among serial MCo2O4(M=Ni,Cu,and Zn)spinel ferrites,redox reactions during synthesis only occurred between Cu and Co elements,thus leading to the presence of multiple crystal phases on final samples.With the aid of increased polyethylene glycol(PEG)molecular weight(MW),more heterogenous interfaces between CuO and CuCo2O4 phases as well as induced crystal defects were generated.Under synergetic interface engineering by means of PEG-assisted redox reaction,interfacial polarization,and defect-induced polar-ization loss were markedly enhanced on a CuCo2O4-based sample that was prepared with PEG MW of 100 K.The effective absorption bandwidth of the corresponding sample could reach 6.48 GHz(11.52-18 GHz)with a thickness of 2.28 mm.In short,this work provides a novel strategy for designing EM wave absorbing composites by interface engineering through redox reaction instead of the conventional composition coupling process.
查看更多>>摘要：The upsurge of interest in the emergence of photocatalytic fuel cell systems(PFC)presents an efficient and environmentally friendly approach to wastewater treatment.In this work,a Z-scheme coupled with an S-scheme heterojunction electrode was used in the PFC,utilizing TiO2/GO/g-C3N4 as the photoan-ode and BiOAc1-xBrx/BiOBr as the photocathode.We systematically align the band structures between the anode and cathode,which facilitates the electron transfer between the electrodes.Our attempt suc-cessfully demonstrates that collaborative power generation facilitates the high efficiency of tetracycline hydrochloride(TC)degradation at both electrodes.The photoanode achieved a 94.87％degradation rate for TC,while the photocathode exhibited a 96.33％degradation rate after 2 h,surpassing pristine BiOBr and BiOAc by factors of～5.3 and～3.8,respectively.Furthermore,this work proposed a mechanism for electron generation,transport,and pollutant degradation mechanism in the PFC.Intermediate substances generated during the degradation of TC were analyzed through high-performance liquid chromatography-mass spectrometry(HPLC-MS)and ultraviolet photoelectron spectroscopy(UPS),while the optimal degra-dation pathway was confirmed using density functional theory(DFT).The findings of this work estab-lish the feasibility of efficiently degrading pollutants through PFC treatment,introducing a novel system where various heterojunctions in bipolar materials collaborate with photocatalysis to effectively generate electricity and enhance pollutant removal.
查看更多>>摘要：Liquid-solid phase separation of permalloy in liquid Mg results in selectively dissolved Ni,which provides a unique opportunity for the design of immiscible heterogeneous composite materials and the compre-hensive metal recycling of permalloy scraps.A guideline of the alloy design for the liquid-solid phase sep-aration system was proposed.The effects of immersion temperature and time on the Ni extraction were studied by an experimental method.The diffusion behavior of Ni from the permalloy to liquid Mg and the microstructure evolution in the permalloy during the liquid-solid phase separation were discussed.The results show that the Ni in the permalloy was quickly extracted into the liquid Mg and formed an Mg-Ni alloy,while the other components such as Fe,Co,and Mn were held back in the phase-separated permalloy.The phase-separated permalloy with the solidified Mg exhibits a three-dimensional(3D)Fe/Mg bicontinuous composite structure.Furthermore,simple treatments were carried out for the reaction prod-ucts such as the Fe/Mg bicontinuous composite and the Mg-Ni alloy,and the recycling strategies for func-tionalization of these treated reaction products were provided.A 3D porous Fe-based alloy with electro-magnetic interference(EMI)shielding efficiency of 52 dB can be obtained if Mg is removed from the Fe/Mg bicontinuous composite.Instead of the complete separation of pure Ni from the recycled Mg-Ni alloy by vacuum distilling,the Mg-Ni alloy can be enriched into Mg2Ni as an initial hydrogen storage material.
查看更多>>摘要：Thermal management is a critical challenge in modem electronics and recent key innovations have fo-cused on integrating diamond directly onto semiconductors for efficient cooling.However,the connec-tion of diamond/semiconductor that can simultaneously achieve low thermal boundary resistance(TBR),minimal thermal budget,and sufficient mechanical robustness remains a formidable challenge.Here,we propose a collective wafer-level bonding technique to connect polycrystalline diamonds and semiconduc-tors at 200 ℃ by reactive metallic nanolayers.The resulting silicon/diamond connections exhibited an ultra-low TBR of 9.74 m2 K GW-1,drastically outperforming conventional die-attach technologies.These connections also demonstrate superior reliability,withstanding at least 1000 thermal cycles and 1000 h of high temperature/humidity torture.These properties were affiliated with the recrystallized microstructure of the designed metallic interlayers.This demonstration represents an advancement for low-temperature and high-throughput integration of diamonds on semiconductors,potentially enabling currently thermally limited applications in electronics.
查看更多>>摘要：To alleviate the pressure on the petrochemical industry and address environmental concerns,the utiliza-tion of polyurethane(PU)derived from castor oil(CO)(as an ester polyol replacement of petrochemical-based materials)has garnered significant attention in recent decades.Extending the service life of ma-terials requires imparting self-healing properties to vegetable oil-based polymers,an aspect that has re-ceived limited attention in current studies.However,low self-healing efficiency still poses a significant challenge,and non-conductivity also remains an obstacle in current research,crucial for their application in electronic devices.In this work,we present the first series of electrically self-healing biopolymer com-posites constructed by incorporating carbon nanotube(CNT)networks into crosslinked castor oil-based polyurethane(BPU)through a simple curing process.These materials address the challenges mentioned above and exhibit improved mechanical,electrical,and self-healing capabilities compared to other bio-based self-healing materials.The resulting BPU/CNT composite demonstrated exceptional repeated self-healing capacity,restoring both mechanical properties and electrical performance even after experiencing severe mechanical damage.Notably,this composite served as a conductive substrate in flexible solid-state supercapacitor(FSSC)devices.Consequently,the FSSC derived from the composite conductive substrate achieved an impressive 92.4％self-healing efficiency even after undergoing 7 cutting/healing cycles.The device remained virtually unchanged even after being bent at a 180° angle with a bending radius of 1.6 mm,indicating excellent repeatability and durability.The exceptional self-healing ability,with～98％electrical recovery at 100 ℃ for 70 s and 93％at 80 ℃ after 6 min,of these composites was attributed to the synergistic interactions of the dynamic exchange reactions of disulfide bonds and dense hydrogen bonds within the BPU matrix,which provide a reversible dynamic polymer network.The healing effi-ciency of these dynamic bonds was evaluated by adjusting the composition ratio of the long linear chain of pTHF in hybrid polyols of the crosslinked polymer network.Overall,this work highlights a series of green,simple,and highly efficient self-healing polymer composites derived from renewable castor oil,and it establishes an essential framework for future sustainable polymer composite design.
查看更多>>摘要：Ingenious microstructure design and rational composition collocation have been proved to be an effec-tive strategy for developing efficient electromagnetic wave(EMW)absorbers.It would be promising to fabricate a hollow structured composite integrating multiple loss mechanisms(conduction,magnetic,and polarization losses)for excellent EMW absorption.Herein,a novel dielectric-magnetic compound of ZnO/Ni@C hollow microsphere was prepared through hydrothermal reactions followed by an in-situ chemical vapor deposition(CVD).In this ternary composite,abundant ZnO/Ni heterostructures formed the hollow microsphere skeletons and provided unique Schottky junctions,which endowed the com-posite with improved impedance matching and strong polarization loss.Meanwhile,the amorphous-polycrystalline carbon layer deposited on the surface of each microsphere enhanced the conduction and interfacial polarization losses.In addition,the magnetic Ni nanoparticles induced magnetic loss.Benefit-ing from the synergistic effect of the hollow structure and multiple loss mechanisms,the ternary com-posite exhibits an effective absorption bandwidth as wide as 6.55 GHz at a thickness of only 1.85 mm,accompanied by a minimum reflection loss of-39.8 dB.Besides,the radar cross-section and the elec-tromagnetic field simulation further verify the superior EMW absorption performance of the composites.Our work provides a new reference for the fabrication of dielectric-magnetic ternary hollow microspheres as EMW absorbers with thin thickness and broad bandwidth.
查看更多>>摘要：Overcoming the trade-off between saturation magnetic induction(Bs)and coercivity(Hc)of Fe-based nanocrystalline alloys(FNAs)remains a great challenge due to the traditional design relying on trial-and-error methods,which are time-consuming and inefficient.Herein,we present an interpretable machine learning(ML)algorithm for the effective design of advanced FNAs with improved Bs and low Hc.Firstly,the FNAs datasets were established,consisting of 20 features including chemical composition,process pa-rameters,and theoretically calculated parameters.Subsequently,a three-step feature selection was used to screen the key features that affect the Bs and Hc of FNAs.Among six different ML algorithms,extreme gradient boosting(XGBoost)performed the best in predicting Bs and Hc.We further revealed the associ-ation of key features with Bs and Hc through linear regression and SHAP analysis.The valence electron concentration without Fe,Ni,and Co elements(VEC1)and valence electron concentration(VEC)ranked as the most important features for predicting Bs and Hc,respectively.VEC1 had a positive impact on Bs when VEC1＜0.78,while VEC had a negative effect on Hc when VEC＜7.12.Optimized designed FNAs were successfully prepared,and the prediction errors for Bs and Hc are lower than 2.3％and 18％,re-spectively,when comparing the predicted and experimental results.These results demonstrate that this ML approach is interpretable and feasible for the design of advanced FNAs with high Bs and low Hc.
查看更多>>摘要：Three-dimensional(3D)bioprinting has revolutionized tissue engineering by enabling precise fabrication with bioinks.Among these techniques,digital light processing(DLP)stands out due to its exceptional resolution,speed,and biocompatibility.However,the progress of DLP is hindered by the limited avail-ability of suitable bioinks.Currently,some studies involve simple mixing of different materials,resulting in bioinks that lack uniformity and photopolymerization characteristics.To address this challenge,we present an innovative one-pot synthesis method for bioinks based on methacrylated gelatin/alginate with hydroxyapatite(HAP).This approach offers significant advantages in terms of efficiency and uniformity.The synthesized bioinks demonstrate excellent printability,stability,and notably enhanced mechanical properties,facilitating optimal in vitro compatibility.Additionally,the HAP-hybrid bioinks printed scaf-folds demonstrated impressive bone repair capabilities in vivo compared with pure organic bioinks.In conclusion,the Gel/Alg/HAP bioinks presented herein offer an innovative solution for DLP bioprinting within the field of bone tissue engineering.Their multifaceted advantages help overcome the limitations of restricted bioink choices,pushing forward the boundaries of bioprinting technology and contributing to the progress of regenerative medicine and tissue engineering.
查看更多>>摘要：Lithium-sulfur(Li-S)batteries have the advantages of high-energy-density,low cost,and environmental friendliness,but the sluggish sulfur redox reactions and the severe shuttle effect of lithium polysulfide(LiPSs)affect their performance.Herein,we developed a highly efficient electrocatalyst(CNT/HEA-NC)consisting of high-entropy alloy(HEA)nanoparticles decorated with nitrogen-doped carbon(NC)and car-bon nanotubes(CNTs)conductive networks.In the elaborate nanostructured protocol,the HEA nanopar-ticles with high catalytic activity accelerate the bidirectional conversion of LiPSs,the NC with strong sul-fophilic activity effectively adsorb LiPSs to suppress the shuttle effect,and the CNT conductive network provides a fast electrons/ions transport pathway.Benefiting from the hierarchical confinement,Li-S bat-teries with CNT/HEA-NC modified separators deliver a discharge specific capacity of 692.0 mA h g-1 after 300 cycles at 1 C with a capacity decay rate of only 0.03％per cycle.Even at a current density of 5 C,the cell exhibits a superior capacity of 521.1 mAh g-1.This work provides a general strategy for integrating multifunctional electrocatalysts for high-performance Li-S batteries.
查看更多>>摘要：Chromium oxide ceramic materials are widely used in high-temperature applications requiring high wear resistance and lubricity.To further improve the friction and wear performance and high-temperature sta-bility of chromium oxide thin films,this study attempted to dope rare earth(RE)element Y(yttrium)and deposited CrYO high-temperature self-lubricating ceramic thin films with different doping levels on the surface of IN718 alloys by using multi-arc ion plating technology.The deposited films were annealed at 1000 ℃ for 2 h under atmospheric conditions to analyze the changes in phase composition and thick-ness,and the friction and wear characteristics of the CrYO films were tested using a high-temperature friction and wear tester in the temperature range of 25-600 ℃.The results show that the CrYO-2 film has a dense multilayer structure,and the multilayer oxide film produces interlayer sliding under fric-tional shear,thus providing lubrication.In particular,the friction coefficients are as low as about 0.25 in the middle and high-temperature sections(400,600 ℃),which provides good high-temperature tribolog-ical properties.In addition,the doping of Y elements dramatically affects the formation of the oxide layer and the distribution of voids in the film,changing the diffusion process of the elements of the base ma-terial inside the film and at the film-air interface at high temperatures.After two annealing treatments,the film thickness increased from 1.81 to 2.25 μm,and the volume expansion of the films was effectively controlled compared with that of the Cr2O3 films.
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