查看更多>>摘要：Localized CdS homojunctions with optimal ratio of high and low index facets are constructed to dy-namically boost H2O splitting into H2 energy by hydrothermal method in combination with calcination.By density functional theory,hall effect,and in situ diffuse reflectance infrared Fourier transform spec-troscopy,it is revealed that photo-irradiated e-and h+can be spatially separated and directionally trans-ferred to the reductive high-index facet ｛002} and oxidative low-index facet {110} of localized CdS homo-junction induced by Fermi level difference of both high and low index facets to dehydrogenate*-OH and coupled*-O intermediates for H2 and O2 yield,respectively,along with a solar conversion into hydrogen of 1.93％by AM 1.5 G irradiation at 65 ℃.The study work suggests a scientific perspective on the optimal ratio of high and low index facets to understand photo-generated charge carrier transfer dynamically and their photocatalytic principle for H2O splitting reaction in kinetics.
查看更多>>摘要：Graphene has been extensively utilized in the domain of electromagnetic wave(EMW)absorption ma-terials because of its excellent electrical conductivity.However,the inferior impedance matching per-formance and the single loss mechanism vastly restrict the application.Hence,it's an effective strat-egy to solve these issues by introducing magnetic components.Notably,layer double hydroxide(LDH)is an appropriate template to obtain magnetic component materials.Considering that ferromagnetic met-als such as Fe,Co,Ni,and their corresponding metal oxides are usually treated as magnetic compo-nents which are promising candidates for EMW absorption materials.Therefore,in this work,a FeNi-layered double hydroxide-reduced graphene oxide(FeNi-LDH-rGO)aerogel was synthesized through a series of processes such as electrostatic self-assembly,hydrothermal,freeze-drying,and annealing.The magnetic NiFe2O4@FeNi3 core-shell nanospheres were obtained from FeNi-LDH precursor,anchoring on rGO nanosheets after the annealing treatment.Furthermore,the effects of different mass ratios of LDH to GO as well as different annealing temperatures of LDH-rGO aerogel on the EMW absorption prop-erty and impedance matching performance were explored.As a consequence,the fabricated ultralight 600LDH-rGO 2:1 aerogel shows a broad effective absorption bandwidth(EAB)of 7.04 GHz at a thickness of 2.3 mm with a low filling content of only 6 wt％and a low density of 4.4 mg/cm3.In conclusion,the synthetic LDH-rGO aerogels offer an effective strategy for preparing EMW absorption materials that own three-dimensional porous network structure and unique magnetic NiFe2O4@FeNi3 core-shell struc-ture nanospheres.
查看更多>>摘要：Abnormal grain growth(AGG)easily takes place in Mg alloys during high-temperature solutions,result-ing in deterioration of mechanical properties.Hence,the compression prior to solution(pre-compression)was conducted to suppress AGG,and the microstructure evolution as well as suppressing mechanisms was investigated based on quasi-in-situ analysis.After compression along the transverse direction,＜11-20＞//ED grains preferentially nucleated and rapidly grew up,and the initial＜10-10＞//ED texture was weakened.Two grain growth modes of heat-induced and strain-induced grain boundary migrations were found.The former was attributed to the high interfacial energy of grain boundaries with large curvature.The latter consumed the adjacent grains with high storage energy,forming abnormal grains with irregular shapes.The compression with a reduction＞6％could obviously suppress AGG.The suppressing effects were mainly attributed to weakening the size advantage of＜11-20＞//ED grains,increasing nucleation,reducing grain boundary character distribution,and redistributing storage energy distribution.After 12％compression along the transverse direction,30° misorientation of＜11-20＞//ED grains and high energy grain boundaries were reduced.The {10-12} tensile twins and {10-15} high index twins induced by com-pression increased the nucleation of static recrystallization.Beside,compression introduces high-density dislocations,which also contributed to suppressing AGG behavior during solution.
查看更多>>摘要：Microbes can cause or accelerate metal corrosion,leading to huge losses in corrosion damages each year.Geobacter sulfurreducens is a representative electroactive bacterium in many soils,sediments,and wastew-ater systems.It has been confirmed to directly extract electrons from elemental metals.However,little is known about the effect of electron shuttles in G.sulfurreducens corrosion on stainless steel.In this study,we report that exogenous flavins promote iron-to-microbe electron transfer,accelerating micro-bial corrosion.G.sulfurreducens caused 1.3 times deeper pits and increased electron uptake(with 2 times increase of icorr)from stainless steel when riboflavin was added to the culture medium.OmcS-deficient mutant data suggest that G.sulfurreducens utilizes riboflavin as a bound-cofactor in outer membrane c-type cytochromes.The finding that,in the presence of microbes,riboflavin can substantially accelerate corrosion highlights the role of flavin redox cycling for enhanced iron-to-microbe electron transfer by G.sulfurreducens and provides new insights in microbial corrosion.
查看更多>>摘要：As a new type of nonvolatile memory,the resistive memristor has broad application prospects in in-formation storage and neural computing based on its excellent resistive switching(RS)performance.At present,it is still a great challenge to improve both ferroelectric polarization and leakage current to achieve a high RS on/off ratio of ferroelectric memristors.Herein,epitaxial Pb(Zr0.40Ti0.60)O3(PZT)thin films with low content Ca doping were deposited on the Nb:SrTiO3 substrate to prepare PCZT/NSTO het-erostructures and their RS behaviors were studied.The research findings show that compared with pure PZT film,the ferroelectric polarization of 1-mol％-Ca-doped PZT film is slightly improved,while the leak-age current is increased by three orders of magnitude.Therefore,the RS on/off ratio reaches 2.5 x 105,about three orders of magnitude higher than pure PZT films.The theoretical analysis reveals that the RS behavior of PCZT/NSTO heterostructures is controlled by the PCZT/NSTO interfacial barrier and the space charge-limited current mechanism.Our results demonstrate that the ferroelectricity and electricity of ferroelectric thin films can be improved simultaneously by doping low-content Ca ions to increase the RS performance,which provides a good reference for the development of high-performance ferroelectric memristor devices.
查看更多>>摘要：Recently,Yu and co-workers deeply explore the potential impact of free electron transfer between co-catalysts and photocatalyst carriers on H2 evolution efficiency of active sites over MoS2+x.They pro-pose an electron-reversal tactics to evade the unexpected electron transfer and synchronously regulate the above transfer in a beneficial orientation for weakening hydrogen adsorption on S sites.Herein,this highlight not only discusses and summarizes the essences of electron reversal and the optimized H ad-sorption/desorption mechanism,but also emphasizes the significance of femtosecond transient absorp-tion spectroscopy(fs-TAS)and in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS)for revealing charge transfer dynamics and processes.We anticipate that this highlight can disseminate a new per-spective on the roles of photocatalyst carriers in improving cocatalytic H2-production kinetics.
查看更多>>摘要：Amorphous/nanocrystalline dual-phase structures have recently emerged as an effective way for over-coming the strength-ductility trade-off and breaking the limitation of the reverse Hall-Petch effect.Here,we proposed a new strategy to develop a hierarchical and interconnected amorphous-crystalline nanocomposite arising from the nanoscale elemental interdiffusion and oxygen adsorption behavior dur-ing thermal treatment processes.The nanocomposite consisted of a three-dimensional(3D)hierarchical network structure where the crystalline phase(Cr-Co-Ni-Al)was embedded into the Al-O-based amor-phous phase network with critical feature sizes encompassing three orders of magnitude(from microm-eter to nanometer scale).It can achieve ultrahigh compression yield strength of～3.6 GPa with large homogeneous deformation of over 50％strain.The massive interstitial atoms induced lattice distortion and hierarchical amorphous phase boundary contributed to the strength improvement.in situ Uniaxial compression inside a transmission electron microscope(TEM)revealed that the exceptional deformability of the nanocomposites resulted from the homogenous plastic flow of nano-sized amorphous phase and the plastic co-deformation behavior restricted by the nano-architected dual-phase interface.The proposed dual-phase synthesis approach can outperform conventional nanolaminates design strategies in terms of the mechanical properties achievable while providing a pathway to easily tune the microstructure of these nanolaminates.
查看更多>>摘要：Photocatalytic technology with sunlight as driving force can convert solar energy into other energy sources for storage and further use.Cadmium sulfide(CdS),as a typical reducing semiconductor of metal sulfides,represents an interesting research hotspot in photocatalysis due to its suitable bandgap(2.4 eV)for utilizing visible light and strong reducing ability for inducing surface catalytic reactions.Unfortunately,the photocatalytic performance of CdS is still limited by its fast carrier recombination and serious pho-tocorrosion.So far,CdS semiconductor has been widely developed as a typical reducing photocatalyst in constructing novel S-scheme heterojunction to overcome the above drawbacks.In this review,the de-sign concepts,basic principles,and charge transfer characteristics of CdS-based S-scheme heterojunction photocatalysts have been comprehensively introduced.Several advanced and effective characterization methods for studying the mechanism of CdS-based S-scheme heterojunction are analyzed in detail.Fur-thermore,we also summarize the typical applications of CdS-based S-scheme heterojunctions for water splitting,CO2 reduction,pollutant degradation,etc.Eventually,according to the current investigation sta-tus,some drawbacks in the current synthetic strategy,mechanism exploration,and application prospect of CdS-based S-scheme heterojunction are proposed,which need to be addressed by further expansion and innovative research.
查看更多>>摘要：The S-scheme heterojunction has garnered increasing attention due to its remarkable oxidation capacity and efficient separation of photogenerated carriers.In this study,a one-pot glycerol-assisted hydrothermal process was utilized to successfully synthesize S-scheme heterojunction photocatalysts comprising basic bismuth nitrate(BBN)and bismuth tungstate(BWO).Interestingly,the BBN/BWO heterogeneous photo-catalysts exhibited the highest photocatalytic properties.The optimized product achieved the degradation of sulfamethazine(SMZ)within 1 h,with a kinetic constant(k)value of 0.05818 min-1.The degradation process was influenced significantly by·O2-and h+species.To determine the degradation pathway of SMZ in the presence of BBN/BWO-0.6,liquid chromatography-mass spectrometry(LC-MS)analysis was performed,which revealed a decrease in the toxicity of intermediates and products.The enhanced pho-tocatalytic activity can be attributed to the internal electric field(IEF)of the S-scheme heterojunction between BBN and BWO,effectively promoting the separation of photogenerated carriers.This research presents a viable approach for developing S-scheme heterojunctions in SMZ photodegradation and other environmental applications.
查看更多>>摘要：Designing microstructurally stable FeCrAl alloys with excellent strength-ductility synergy is highly desir-able for their engineering applications.However,due to the preference nucleation of precipitates at grain boundaries(GBs),the improved precipitation strengthening of these alloys is usually accompanied by in-tergranular embrittlement.Here,we propose a novel thermomechanical processing route coupled with the Si alloying strategy via precipitation of coherent deformable Laves precipitates inside equiaxed fine-grains to achieve FeCrAl alloys with ultrahigh yield strength over～992 MPa,excellent uniform elongation of～7.6％at room temperature,and superior thermal stability at temperature～1200 ℃.The Si alloying not only decreases the stacking fault energy of Laves precipitates favorable for their stacking-fault-mediated deformation but also hinders grain coarsening at 1200 ℃ due to the Si-enrichment favorable for GB pin-ning effects.Our results prove the possibility of achieving the collaborative enhancement of mutually exclusive properties in alloys,such as strength-ductility-thermal stability via nanoprecipitation engineer-ing,and offer a promising route to prepare dispersion-strengthened materials.
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