查看更多>>摘要：The escalating electromagnetic(EM)pollution issues and the demand to elevate military stealth technology make it imperative to develop cost-effective and high-performance electromagnetic wave(EMW)absorbing materials.In this paper,the flower-like CuS/γ-Fe2O3 van der Waals(vdW)heterostructures have been synthesized via a facile two-step solvothermal approach.The flower-like CuS skeleton increases the attenuation path of EMW while reducing the material density.Different contents of γ-Fe2O3 nanoparticles anchor between the flower-like CuS nanosheets to constitute a heterogeneous structure,which enables dielectric and magnetic loss synergistically to optimize impedance matching and remarkably improve the EMW absorption performance.The minimum reflection loss(RLmin)is-49.36 dB with a thickness of only 1.6 mm and the effective absorption bandwidth(EAB)reaches 4.64 GHz(13.36-18 GHz).By adjusting the thickness of the absorber,the EAB can cover 96％of the GHz band.Notably,the superior absorption of-61.53 dB at middle frequency band can be obtained by adjusting the amount of Fe2O3 addition.In this study,the adjustment of EM parameters and the optimization of impedance matching have been achieved by constructing a novel vdW heterogeneous structure,which provides fresh ideas and references for the design of high-performance EMW absorbing materials.
查看更多>>摘要：Heterogeneous doping is one effective strategy for synthesizing metal alloy nanowires.Herein,the heterogeneous doping processes of Pd on the ultrathin Au nanowires were systematically modulated and investigated.Au-Pd alloy nanowires with various morphologies and lattice structures can be obtained by adjusting the morphology of the precursor Au nanowires and the kinetics of the heterogeneous doping processes.The effects of the rate of Pd reduction and the concentration of the ligand oleylamine(OAm)on the Pd deposition and alloying mode were articulated.Generally,as the Pd deposition rate decreases,the Pd deposition and alloying mode switches from the island-forming Stransky-Krastanov(SK)mode to the epitaxial Frank-van der Merwe(FM)mode,and eventually to an unconventional twisting alloying mode,where the interdiffusion of Pd and Au causes drastic rearrangement of the lattice structure and formation of helical structures.The kinetics-related variation of alloying mode could also be observed in the Au-Ag nanowires,demonstrating a general design principle for the synthesis of alloy nanostructures.In addition,the electrocatalytic performance of various Au-Pd nanowires was evaluated,and the alloy nanowire formed via the SK mode was found to be an excellent electrocatalyst for oxygen reduction and ethanol oxidation.
查看更多>>摘要：Chemical functional groups on solid surfaces greatly influence contact electrification(CE)at water-solid interfaces.Previous studies of their effects mainly swapped materials or bonded related molecules to a substrate,introducing other factors of influence.This work aims at unambiguously demonstrating the role of functional groups in water-polymer CE.We study the contribution of functional groups,by using ion coupled plasma etching to modify a high-density polyethylene(HDPE)film,a polymer with a naturally quasi-null charge transfer ability.Fluoride(HDPE-F)and hydroxyl(HDPE-OH)functional groups are generated and endowed HDPE with charge withdrawing ability.HDPE-F withdraws 2.5-2.7 times more charges than HDPE-OH.Concurrently,the surface charges accumulated generate electrostatic forces,altering the droplets motion.This phenomenon provides another approach to study CE,helping to evaluate the contribution of electrons to solid-liquid CE.Finally,employing HDPE-F to perform contact-electro-catalysis shows its activity is 2.4 times higher than that of commercial fluorinated films.
查看更多>>摘要：Herein we proposed a data-driven high-throughput principle to screen high-performance single-atom materials for hydrogen evolution reaction(HER)and hydrogen sensing by combing the theoretical computations and a topology-based multi-scale convolution kernel machine learning algorithm.After the rational training by 25 groups of data and prediction of all 168 groups of single-atom materials for HER and sensing,respectively,a high prediction accuracy(＞0.931 R2 score)was achieved by our model.Results show that the promising HER catalysts include Pt atoms in C4 and Sc atoms in C1N3 coordination environment.Moreover,Y atoms in C4 coordination environment and Cd atoms in C2N2-ortho coordination environment were predicted with great potential as hydrogen sensing materials.This method provides a way to accelerate the discovery of innovative materials by avoiding the time-consuming empirical principles in experiments.
查看更多>>摘要：The development of multifunctional materials and synergistic applications of various functions are important conditions for integrated and miniaturized equipment.Here,we developed asymmetric MXene/aramid nanofibers/polyimides(AMAP)aerogels with different modules using an integrated molding process.Cleverly asymmetric modules(layered MXene/aramid nanofibers section and porous MXene/aramid nanofibers/polyimides section)interactions are beneficial for enhanced performances,resulting in low reflection electromagnetic interference(EMI)shielding(specific shielding effectiveness of 2483(dB·cm3)/g and a low R-value of 0.0138),high-efficiency infrared radiation(IR)stealth(ultra-low thermal conductivity of 0.045 W/(m·K)and IR emissivity of 0.32 at 3-5 μm and 0.28 at 8-14 μm),and excellent thermal management performances of insulated Joule heating.Furthermore,these multifunctional AMAP aerogels are suitable for various application scenarios such as personal and building protection against electromagnetic pollution and cold,as well as military equipment protection against infrared detection and EMI.
查看更多>>摘要：The ionic conductive elastomers show great promise in multifunctional wearable electronics,but they currently suffer from liquid leakage/evaporation or mechanical compliance.Developing ionic conductive elastomers integrating non-volatility,mechanical robustness,superior ionic conductivity,and ultra-stretchability remains urgent and challenging.Here,we developed a healable,robust,and conductive elastomer via impregnating free ionic liquids(ILs)into the ILs-multig rafted poly(urethane-urea)(PUU)elastomer networks.A crucial strategy in the molecular design is that imidazolium cations are largely introduced by double-modification of PUU and centipede-like structures are obtained,which can lock the impregnated ILs through strong ionic interactions.In this system,the PUU matrix contributes outstanding mechanical properties,while the hydrogen bonds and ionic interactions endow the elastomer with self-healing ability,conductivity,as well as non-volatility and transparency.The fabricated ionic conductive elastomers show good conductivity(3.8 × 10-6 S·cm-1),high mechanical properties,including tensile stress(4.64 MPa),elongation(1470％),and excellent healing ability(repairing efficiency of 90％after healing at room temperature for 12 h).Significantly,the conductive elastomers have excellent antifatigue properties,and demonstrate a highly reproducible response after 1000 uninterrupted extension-release cycles.This work provides a promising strategy to prepare ionic conductive elastomers with excellent mechanical properties and stable sensing capacity,and further promote the development of mechanically adaptable intelligent sensors.
查看更多>>摘要：High entropy alloys(HEA)are frequently employed as catalysts in electrocatalytic hydrogen evolution.However,the traditional high entropy alloy synthesis methods are time-consuming,energy-intensive,and environmentally polluting,which limits their application in the hydrogen evolution reaction(HER).This study leveraged the capabilities of flash Joule heating(FJH)to synthesize carbon-supported high-entropy alloy sulfide nanoparticles(CC-S-HEA)on carbon cloth(CC)with good self-standing properties within 300 ms.The carbon thermal shock generated by the Joule heating could pyrolyze the sulfur source into gas,resulting in numerous pore structures and defects on CC,forming an S-doped carbon substrate(CC-S).Then the S atoms were used to stably anchor the metal atoms on CC-S to form high-density uniformly dispersed HEA particles.The electrochemical test results demonstrated that CC-S-HEA prepared at 60 V flash voltage had HER performance comparable to Pt/C.The density functional theory(DFT)calculation indicated that the S atoms on CC-S accelerated the electron transfer between the carbon substrate and HEA particles.Moreover,the unique electronic structure of CC-S-HEA was beneficial to H*adsorption and promoted catalytic kinetics.The simplicity and versatility of FJH synthesis are of great significance for optimizing the synthesis of HEA and improving the quality of HEA products,which provides a broad application prospect for the synthesis of nanocatalysts with efficient HER performance.
查看更多>>摘要：Metal oxide supported metal catalysts show promising catalytic performance in many industry-relevant reactions.However,the enhancement of performance is often limited by the insufficient metal/metal oxide interface.In this work,we demonstrate a general synthesis of Pt-early transition metal oxide(Pt-MOx,M=Ti,Zr,V,and Y)catalysts with rich interfacial sites,which is based on the air-induced surface segregation and oxidation of M in the supported Pt-M alloy catalysts.Systematic characterizations verify the dynamic structural response of Pt-M alloy catalysts to air and the formation of Pt-MOx catalysts with abundant interfacial sites.The prepared Pt-TiOx interfacial catalysts exhibit improved performance in hydrogenation reactions of benzaldehyde,nitrobenzene,styrene,and furfural,as a result of the heterolytic dissociation of H2 at Pt-metal oxide interfacial sites.
查看更多>>摘要：Efficient and selective extraction of uranium(U(VI))from seawater is essential for sustainable nuclear power production.This study reports a novel adsorbent zeolitic imidazolate framework(ZIF)-67@SiO2-A/polyacrylamide(PAM)which was synthesized by grafting the core-shell metal-organic frameworks(MOFs)-based nanostructures coated with the 3-aminopropyl triethoxysilane(APTES)functionalized SiO2(SiO2-A)onto PAM hydrogel.The SiO2 shell was grown on the surface of MOF,which improved the acid-base resistance of MOF.The introduction of ZIF-67@SiO2-A enhances the specific surface area and adsorption efficiency of the PAM.The ZIF-67@SiO2-A/PAM shows remarkable adsorption capacity,fast adsorption kinetics,and good reusability for uranium.It has excellent adsorption property(6.33 mg·g-1,30 d)in natural seawater.The X-ray photoelectron spectroscopy(XPS),Fourier transform infrared(FTIR),energy dispersive spectroscopy(EDS)mappings,and density functional theory reveal that the coordination by N and O in ZIF-67@SiO2-A/PAM with uranium is the main mechanism of uranium adsorption.Thus,ZIF-67@SiO2-A/PAM has great potential to capture uranium from natural seawater.
查看更多>>摘要：Discovering more and new geometrically frustrated systems remains an active point of inquiry in fundamental physics for the existence of unusual states of matter.Here,we report spin-liquid-like behavior in a two-dimensional(2D)rhombic lattice Fe-metal-organic framework(Fe-MOF)with frustrated antiferromagnetism.This Fe-MOF exhibits a high frustration factor f=|θcw|/TN ≥315,and its long-range magnetic order is suppressed down to 180 mK.Detailed theoretical calculations demonstrate strong antiferromagnetic coupling between adjacent Fe3+ions,indicating the potential of a classical spin-liquid-like behavior.Notably,a T-linear heat capacity parameter,γ,originating from electronic contributions and with magnetic field independence up to 8 T,can be observed in the specific heat capacity measurements at low-temperature,providing further proof for the spin-liquid-like behavior.This work highlights the potential of MOF materials in geometrically frustrated systems,and will promote the research of exotic quantum physics phenomena.
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