查看更多>>摘要：Although Bi7O9I3 is an oxygen-rich bismuth oxyiodide with higher photocatalytic activity than BiOI,its applicability for photocatalytic oxidation is limited by the rapid recombination of photogenerated carriers and poor reusability.Depositing Bi7O9l3 on flexible macro-sized carbonaceous materials is a promising approach for promoting photogenerated electron migration and improving reusability.In this study,a composite consisting of Bi7O9I3 supported on graphitic carbon paper(Bi7O9l3-CP)was synthesized via the in situ transformation of a BiOl-deposited carbon paper precursor(BiOl-CP).The as-prepared Bi7O9I3-CP exhibited higher visible-light-driven photocatalytic activity than both Bi7O9I3 and BiOI-CP precursor for phenol removal.The improved photocatalytic activity of Bi7O9I3-CP was attributed to its hierarchical structure and promoted carrier separation,as revealed by photoluminescence,pore structure,and reactive radical analyses.Moreover,owing to its macroscale size and flexibility,the Bi7O9I3-CP composite could be easily operated and reused,which are favorable for practical applications.
查看更多>>摘要：Biomolecular self-assembly has lately emerged as an intriguing method for creating stable gas-liquid dis-persions with unique functional characteristics.In this work,protein-metal coordination complexes were designed as the stabilizer for generating ultrastable fire-fighting foam and creating interfacial architec-tures that were actively switched between"rigid"and"mobile"interfacial states of liquid films in re-sponse to changes in pH and bulk solution compositions(metal ions or alkyl polyglycosides).The re-flected light interferometric technique was used to check interfacial states,and the foaming kinetics and rheological response of aqueous solution and liquid foam were investigated by dynamic surface tension tests and oscillatory rheology analysis.The results showed that liquid foams with mobile films with lower yield limits had a faster spreading rate to cover the burning oil,liquid foams with semi-rigid films can-not extinguish fires due to interfacial instability,and the enhanced rheology of the foam with rigid films established a robust and impenetrable barrier to effectively suppress fuel evaporation and combustion.A new correlation between interfacial properties and the fire-fighting performance of foam was proposed,which showed that the fire-extinguishing time of foam could be well correlated by the interfacial states or film lifetime rather than classical thermodynamics entry,spreading,and bridging coefficients(ESB co-efficients).
查看更多>>摘要：Hexagonal BN-coated powders have been widely used in various engineering sectors,however,their pro-ductions are restricted by the complexity of gas-solid reactions.In this study,guided by thermodynamics,a novel approach to synthesize Layer-structured hexagonal BN(hBN)-coated high entropy diboride pow-ders in vacuum was developed,using metal salt Zr(NO3)4·5H2O,HfCl4,NbCl5,TaCl5,C16H36O4Ti,boric acid,and sucrose as raw materials.By adjusting the ratio of carbon to metal source(C/M),powders only consisting of two boride solid solutions and hBN were finally obtained,under an optimal process-ing condition of C/M=5.5 and synthesis temperature of 1400 ℃.Parts of hBN were found to coat on high-entropy metal diborides ceramic(HEB)particles,corresponding formation mechanism for core-shell structured powders was investigated,together with the liquid precursor assisted boro/carbothermal re-duction process.Starting from as-synthesized core-shell powders,(Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)B2-11 vol％hBN ceramics were densified at 1900 ℃ under 50 MPa without holding,with a high relative density of 97.3％.
查看更多>>摘要：Extensive researches have elucidated the pronounced benefits of gradient microstructures for the me-chanical properties of metallic materials.However,the ramifications of gradient microstructures on formability,particularly regarding their effects on bendability,remain inadequately understood.In this work,the effects of gradient microstructure on the bendability of AZ31 Mg alloy sheet are systematically investigated by comparing the microstructure evolution and strain distribution in the sheets with uni-form microstructure(grain size=12.8 μm and 91.3 μm)and gradient microstructure(grain size=11.5-75.4 μm).The results show that the bendability of the sheet with gradient microstructure is significantly improved when the fine grains(FGs)are placed at the outer side(TBE-FG sample)and the bendability is increased by 93.1％compared to the sample with fine and uniform microstructure(CE-FG sample).With coarse grains(CGs)placed at the inner side,the strain at the compressive region of the TBE-FG sample is higher than its counterparts,while the tensile strain at the extended region is lowest among the four samples.Quasi-in-situ bending experiments reveal that the CGs at the inner side of the TBE-FG sample undergo more twinning.Moreover,the increment of residual dislocation density at the outer side of the TBE-FG sample is lower than those of other samples,which extends the bending potential.This work provides a novel perspective to improve the bendability of the Mg alloy sheet.
查看更多>>摘要：The high energy density and long cycling life of zinc-based batteries are restricted by the single electro-chemical reaction system.To improve the electrochemical performance of batteries,electrode materials,electrolytes and membranes are regularly modified,while the construction of battery systems is often ne-glected.Herein,a multifunctional electrode was prepared via 3D printing,which successfully coupled the metal oxide/hydroxide-zinc battery(MZB)reaction and rechargeable zinc-air battery(RZAB)reaction.The ultrathick hierarchical 3D electrode provided a tunable capacity for the MZB system,which enabled the possibility for feasible output regulation of this hybrid system.The active material NiCoLDH was discov-ered to undergo structure reconstruction during cycling,which revealed the capacity fading mechanism.The delicate system design and discovery ensured a high-performance battery configuration and revealed the corresponding mechanism,opening a new avenue for developing high-performance zinc batteries.
查看更多>>摘要：Metamaterials with artificial designability and perfect absorption provide a novel design method for the manipulation and attenuation of microwaves.However,owing to the limitations of meta-atomic reso-nance effect and the lossless medium,it is difficult to achieve effective microwave absorption in a broad-band frequency range.Hence,an ultra-wideband metamaterial absorber(UWMA)composed of two mag-netic media and a metasurface was designed,and the absorption bandwidth of 2.9 to 18 GHz for 90％absorptivity under normal incidence was achieved,covering almost the entire S,C,X,and Ku bands.Through detailed investigation of equivalent circuit,equivalent medium theory,electromagnetic field dis-tribution and front-back interface interference,the internal physical working mechanism was clarified essentially.In addition,the multi-environment adaptabilities of the proposed absorber,including polariza-tion sensitivity,large angle incidence,dual-station radar stealth,bearing capacity and corrosion resistance,were analyzed.The proposed metamaterial absorber presents an effective way to achieve ultra-wideband absorption and compatibility with environmental adaptability,and provides a new way of thinking for intelligent full-band stealth technology.
查看更多>>摘要：The practicality of electrochemical water-splitting technology relies on the development of novel and efficient bifunctional electrocatalysts capable of facilitating both the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).Black phosphorus(BP)holds tremendous promise for HER and OER electrocatalysis owing to its fully exposed atoms and high carrier mobility.However,the elec-trocatalytic performance of BP is still much lower than the expected theoretical limit,presenting an exciting challenge for further advancements.Herein,we embed electrochemically exfoliated few-layer BP nanosheets in higher Fermi level(EF)of cobalt,nitrogen co-doped carbons to form a new heterojunction(CoNC-BP),as efficient bifunctional electrocatalysts toward HER and OER for the advancement overall water splitting applications.A directed interfacial electron transfer is realized from CoNC to BP,facilitated by the lowering Fermi level(EF).This interfacial electron transfer plays a crucial role in optimizing the adsorption and desorption of active intermediates,while also introducing an abundance of hypervalent Co sites.These factors collectively contribute to the remarkable electrocatalytic activities of HER and OER performance,leading to the efficient performance of the developed CoNC-BP heterojunction in water-splitting applications.This work demonstrates a promising breakthrough that can inspire the design of high-efficiency catalysts.
查看更多>>摘要：Graphene-based phase change composites hold significant potential for solar energy utilization,but their poor thermal conductivity hinders their practical applications.In this work,an air-dried graphene skele-ton(AGS)with excellent thermal conductivity enhancement efficiency was constructed by the ice tem-plating method and syneresis,and the air-dried graphene phase change composite(AGP)was subse-quently obtained through vacuum-impregnating n-Docosane(C22)into AGS.The syneresis effectively re-duced the phonon scattering between graphene sheets within AGS and increased the density of AGS to 0.1701 g/cm3.Therefore,with a graphene skeleton loading of 23.82 wt.％,AGP exhibited excellent thermal conductivity of 9.867 W/(m K),outstanding electrical conductivity of 68.08 S/cm,and remarkable shape stability.Additionally,AGP demonstrated a melting enthalpy of 188.5 J/g and an outstanding solar-thermal conversion efficiency of 93.98％,showing enormous potential for the utilization of solar energy.
查看更多>>摘要：In this study,the oxidation behavior of Ti42Al5Mn,Ti42Al5Mn0.5 W,Ti42Al5Mn0.5W0.1B,and Ti42Al5Mn0.8 W was investigated at 800 ℃.Due to the inability to form a dense protective Al2O3 layer,Ti42Al5Mn suffered severe spallation during oxidation at 800 ℃ and the mass gain was significant.The intermediate layer between the scale and the substrate was first composed of Laves/Z phase but changed to α2/Z phase with prolonged oxidation.The intermediate layer with high Ti/Al ratio favors the forma-tion of a thick Al2O3+TiO2 mixed layer in the oxide scale which is prone to initiate cracks and cause the spalling of oxides.The doping of W in TiO2 effectively inhibited its generation and promoted the for-mation of a dense Al2O3 layer,resulting in a significant improvement in the oxidation resistance of the alloy.Compared to Ti42Al5Mn alloy,Ti42Al5Mn0.8 W showed no spallation after 300 h cyclic oxidation and the kinetic curve changed from liner law to parabolic law.The intermediate layer of Ti42Al5Mn0.8 W alloy was composed of a single Laves phase and remained unchanged even after 1000 h oxidation at 800 ℃,offering a favorable basis for the generation of a stable protective oxide layer in the alloy.The addi-tion of 0.1 at.％B to Ti42Al5Mn0.5 W alloy refined its microstructure and further improved its spallation resistance to a level close to that of Ti42Al5Mn0.8 W alloy.
查看更多>>摘要：Surface structural engineering is desirable in modifying the surface performance of carbonyl iron powder(CIP)to enhance microwave absorption(MA)and anti-oxidation performance.Herein,the surface shape-dependent CIP absorbers are designed via surface coating with zinc oxide(ZnO)nanoparticles and then a thermal annealing treatment.The morphology of ZnO nanoparticles which can be easily regulated by controlling the annealing temperature ultimately affects the MA performance of CIP coating with ZnO nanoparticles(CIP@ZnO).The core-shell CIP@ZnO particles with cubic cone ZnO nanoparticles exhibit ex-cellent MA performance and thermal stability in comparison to the original CIP.Specifically,the CIP@ZnO annealed at 350 ℃(CIP@ZnO-350)samples which have the cubic cone ZnO nanoparticles exhibit a min-imum reflection loss(RLmin)of-55.35 dB at a thickness of 2.1 mm and a maximum effective absorp-tion bandwidth(EAB)of 7.09 GHz at a thickness of 2.0 mm.In addition,the antioxidant property of the CIP@ZnO composite particles is abruptly enhanced,which breaks the restriction of the application of CIP at high temperatures.The superior MA performance of CIP@ZnO particles with cubic cone ZnO nanoparti-cles comes from the enhancement in surface shape-dependent multiple microwave scattering,interfacial polarization,and electromagnetic-dielectric synergism between ZnO and CIP.
NETL
NSTL
万方数据