查看更多>>摘要：A variety of nanoparticles(NPs)(e.g.,SiO2,TiO2,CeO2,Co3O4,etc.)and their functionalized counterparts have been intensively investigated for improving the electrochemical and mechanical durability of polymer-based proton-exchange membranes(PEMs)for use in low-and intermediate-temperature fuel cells.This study is to conduct a comprehensive review on the roles of functionalized NPs in the performance enhancement of PEMs including proton conductivity,gas crossover resistance,electrochemical and mechanical durability,etc.A brief historical review of PEM fuel cell(PEMFC)technology is made.Typical types of NPs and their functionalization techniques are retrospected and their roles in the performance improvement of PEMs are compared in detail.Consequently,the opportunities and challenges to develop high-performance functionalized NPs for use in PEMs and PEMFCs are prospected and justified.
查看更多>>摘要：The emergence and development of layered materials have shown great promise for many applications,especially in recent years,the effective modulation of the physicochemical properties of layered materials by intercalation chemistry has led to great potential in material design.In this paper,we review the reaction mechanisms of different guest species(metal atoms/ions,organic molecules/ions,inorganic molecules and inorganic ions)intercalated into the host layered materials as well as the recent progress.It is also reviewed that layered intercalated materials with controllable structure and tunable physicochemical properties can be prepared through the occurrence of interactions between different subjects and guests.The specific applications of inter-calation chemistry in the field of electrocatalysis,such as the hydrogen evolution reaction,oxygen evolution reaction,oxygen reduction reaction and other electrocatalytic reactions,are then discussed,with emphasis on the mechanism of the improved catalytic activity and stability of the layered materials after guest intercalation.
查看更多>>摘要：Macrosegregation and shrinkage porosity in large steel ingots are key factors restricting the homogenization of large cast and forged parts.Due to the complex mechanisms of their formation,they have always been challenging issues in the research on solidification control of large steel ingots.The purpose of this review is to systematically revisit the research progress on the mechanisms of macrosegregation and shrinkage porosity formation in large steel ingots,focusing on the mechanisms of formation of'A'type segregation,positive segregation at the top,and negative segregation at the bottom,and their impact on the quality of steel ingots.At the same time,the con-ditions and influencing factors for the formation of shrinkage porosity are analyzed in detail,and the interaction between macrosegregation and shrinkage porosity during the solidification process of steel ingots is discussed.Based on existing research results and challenges,prospects for future research directions are proposed,emphasizing the development of high-precision numerical simulation techniques and experimental research methods to deeply understand the internal mechanisms of segregation and porosity formation,providing a sci-entific basis for formulating effective control strategies.
查看更多>>摘要：The utilization of carbon dioxide is critical to realize the objective of"carbon peak and neutrality".Among various carbon dioxide exploitation approaches,catalytic hydrogenation of carbon dioxide is a significant method to selectively convert the CO2 into methanol and other valuable chemicals.Among these products,methanol is a crucial chemical feedstock that can be utilized as a platform molecule for the synthesis of chemicals and fuels as well as a fuel for internal combustion engines and fuel cells,causing particular interest.Nowadays,Catalytic hydrogenation of carbon dioxide into methanol has shifted its focus on the creation of low-cost,environmentally friendly,and efficient catalysts.Inspired of this,we have concluded the mechanism of catalytic hydrogenation of carbon dioxide,and reviewed the research progress of multiple heterogeneous catalysts with high catalytic application prospect,especially the supported catalysts.
查看更多>>摘要：Cobalt selenide(CoSe2)emerges as a highly promising anode material for lithium-ion batteries(LIBs)owing to its high theoretical capacity and cost-effectiveness.Despite these merits,its practical utilization faces challenges stemming from substantial volume fluctuations and limited electronic conductivity.To tackle these issues,a plum-branch-like structure of CoSe2@N-doped carbon that embedded in one-dimensional N-doped carbon fibers(CoSe2@NC/CFs),is successfully synthesized through an in-situ confinement method.Well-defined CoSe2@NC nanoparticles,featuring diameters between 20～30 nm,are uniformly dispersed on both the inner and outer surfaces of the carbon fibers.The distinctive architecture of CoSe2@NC/CFs ensures an increased number of active sites,elevated electronic conductivity,alleviated volume expansion,and accelerated reaction kinetics.Consequently,the CoSe2@NC/CFs exhibits remarkable cycling performance and exceptional rate capability.Operating at a current density of 1000 mA g-1,the CoSe2@NC/CFs anode sustains a capacity of 664 mA h g-1 with no obvious capacity decay over 500 cycles.Even at a high current density of 5000 mA g-1,it maintains a capacity of 445 mA h g-1 with a mere 0.02％capacity decay per cycle.This study introduces a novel approach to anode material design,showcasing significant advancements in lithium-ion battery technology.
查看更多>>摘要：Though the current research on vanadium-based glass electrodes has made great progress,the conductivity theory of V-based glasses has not been obviously improved and crystals cannot be positioned precisely.The changes in the valence state of V3+,V4+and V5+are regulated by the strong reducing agent Fe2P to realize valence bond transformation of the amorphous electrode,explore the redox process of multi-electron reactions and further optimize the conductivity of electrode materials.VPFe2 and VPFe3 precipitate VO2 crystals and VPFe4 pre-cipitates VO2 and V6O11 crystals.Electron back-scattered diffraction was used to accurately identify the distri-bution and specific positions of both types of crystals.V6O11 crystals exhibit a strong texture according to pole figure and inverse pole figure.XPS reveals that Fe2P and V2O5,undergo a redox reaction during the high-temperature melting process,where V5+is reduced to V4+and V3+and V4+renders a positive influence on conductivity.The addition of Fe2P increases the content of V4+in the glass and VPFe3 glass contains the highest content of V4+,leading to the highest electronic conductivity.V2O5 transforms into VO2 crystals and VO2 transforms into V6O11 with the increase of Fe2P content.The type of nanocrystal precipitation in glass affects electronic conductivity.
查看更多>>摘要：High-entropy alloy nanoparticles(HEA-NPs)have recently sparked great interest in materials science.Their solid-solution states,derived from distinct HEA configurations,make them promising candidates for catalysts with exceptional activity,stability,and tunable performance.However,a comprehensive understanding of the un-derlying mechanisms governing their electrocatalytic behavior is still lacking,hindering the rational design of HEA electrocatalysts.This review summarizes the fundamental knowledge of HEA-NPs,including the structure-activity correlations of HEA-NPs,diverse synthesis strategies,and applications in electrochemical catalysis.The design strategies for guiding improvements in tunable performance were highlighted.The article concludes with insights,perspectives,and future directions,encapsulating the state-of-the-art knowledge and paving the way for further exploration in this dynamic field.
查看更多>>摘要：Li-rich Mn-based materials provide higher capacity than commercial NCM layered materials due to the synergistic redox effect of cations and anions.However,lattice straining and structural collapse caused by the irreversible oxygen release at high voltage range during cycling,which results in severe capacity and voltage decay.Herein,a synergistic strategy of surface-induced spinel structure and F doping is provided to improve the structural sta-bility.The surface spinel structure helps to reduce the structural collapse caused by electrolyte corrosion on the cathode and effectively inhibits voltage decay resulted from structural evolution.The stronger Mn-F bonds are formed by F doping to inhibit migration of transition metal(TM)and induce the uniform deposition of LiF to form the thinner and more stable CEI on the cathode.Accordingly,the designed cathode(LMNO-NF)shows remarkable cycling performance with the capacity retention of 86.68％and voltage retention of 96.6％for 200 cycles at 1C,higher than pristine material(68.76％and 85.75％).Therefore,this simple dual-modification strategy of one-step synthesis is promising for solving the structural evolution and voltage decay of Li-rich Mn-based cathode materials effectively,achieving further commercialization.
查看更多>>摘要：Different alloys can be flexibly combined to meet the performance needs of different parts of the compressor disc by welding process.However,achieving a good combination of dissimilar alloys with different mechanical properties has always been a research difficulty.In this work,a Ti600/Ti2AlNb joint was fabricated through electron beam welding and an isothermal forging was used to optimized its microstructure and mechanical performance.The isothermal forging process increases the ultimate tensile strength(UST)and yield strength(YS)of the Ti600/Ti2AlNb joint by～18％,while～2.5 times the ductility.It is indicated that before forging,the Ti600/Ti2AlNb joint exhibits a much lower strength than that of Ti600 matrix,whereas the opposite is true after isothermal forging.The isothermal forging broken the coarse columnar grains of Ti600/Ti2AlNb joint and render to an equiaxed B2 structure in which the acicular α2 and O phase are precipitated,resulting a synchronous enhancement of strength and ductility.This work may pave an effective routine for improving the comprehensive mechanical properties of dissimilar metal welding joint.
查看更多>>摘要：Magnesium-based hydrogen storage materials represent a hydrogen storage technology with broad application prospects.As the global energy crisis and environmental pollution issues become increasingly severe,hydrogen,as a clean and efficient energy source,has garnered growing attention.Magnesium-based hydrogen storage,serving as a crucial means for storing and transporting hydrogen,is gaining prominence due to its abundant resources,low cost,low density,and high hydrogen storage density.However,challenges in terms of absorption/desorption rates,temperature,activation energy,and enthalpy during hydrogen application impede its devel-opment.To address these challenges,this paper systematically reviews current research on magnesium-based hydrogen storage materials,encompasses their types,characteristics,and hydrogen absorption mechanisms.Furthermore,it delves into the impacts of nanoscale dimensions,alloying,doping,and catalysis on the perfor-mance of magnesium-based materials.The aim is to provide valuable insights for research in related fields.
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