Herein,cure characteristics,morphology,and mechanical properties of natural rubber filled with activated carbon-based materials were investigated.Carbon-based materials were prepared from bagasse,coffee grounds and pi...Herein,cure characteristics,morphology,and mechanical properties of natural rubber filled with activated carbon-based materials were investigated.Carbon-based materials were prepared from bagasse,coffee grounds and pineapple crowns by the pyrolysis method at temperatures in the range of 300℃.As-synthesized carbon materials were characterized by optical microscopy(OM),scanning electron microscopy(SEM),and Fourier-transform infrared spectroscopy(FTIR)to analyze size distribution,morphology,and functional groups,respectively.OM and SEM analysis revealed that particles,flakes,and a small quantity of fiber-like carbon were obtained using bagasse and pineapple crown as raw materials,while honeycomb-like carbon materials can be derived from coffee grounds.To investigate the mechanical properties,natural rubber was filled with carbon black and as-synthesized carbon materials by the internal mixing and compression molding process.Transmission electron microscopy(TEM)was utilized to characterize the dispersion of carbon materials in the rubber matrix.The results of tensile testing showed that the natural rubber mixed with as-synthesized carbon materials from pineapple crowns exhibited 54%and 74%improvement in the ultimate tensile strength and Young’s modulus,respectively,compared with natural rubber without filled carbon materials.The enhancement in mechanical properties by activated carbon materials derived from pineapple crowns can be attributed to the flake-and fiber-like structures and good dispersion of carbon materials in the rubber matrix.In addition,it is higher than that of rubber mixed with carbon black.The results demonstrated that as-synthesized carbon materials from pineapple crowns have the potential materials to substitute carbon black in the rubber compound industry.展开更多
Heteroatom-doped transition metal oxides have attracted great attention as advanced anode materials for lithium-ion batteries due to their high theoretical capacity and superior properties.However,the limited resource...Heteroatom-doped transition metal oxides have attracted great attention as advanced anode materials for lithium-ion batteries due to their high theoretical capacity and superior properties.However,the limited resource availability has led to a substantial rise in prices for valuable metals such as Ni and Co,posing a significant challenge for their application.To address this issue,recycling of these metals from waste materials have gained prominence,and particularly the recovery of Co has been mostly focused on its economic benefits.Herein,we introduced a novel recycling strategy for fabrication of heteroatomdoped CoO_(x)(comprising mainly Co_(3)O_(4)with a minor CoO phase)anode with a yolk–shell structure for lithium-ion batteries,by separating Co from cemented tungsten carbide waste.By employing a simple leaching process and subsequent spray pyrolysis,the yolk–shell structured microsphere comprising CoO_(x)was successfully synthesized.Moreover,the presence of other waste metals in the leachate facilitated multi-heteroatom doping during synthesis.Interestingly,the introduction of various dopants into CoO_(x)induced oxygen vacancy formation,thereby enhancing the electrochemical properties of the CoO_(x)anode.As a result,compared with the phase-pure(undoped)CoO_(x)yolk–shell,the heteroatom-doped CoO_(x)yolk–shell exhibited robust cycling stability(602 mAh·g^(-1)for 200 cycles at 1 A·g^(-1))and excellent rate capability(210 mAh·g^(-1)at 10 A·g^(-1)).展开更多
K–Se batteries have been identified as promising energy storage systems owing to their high energy density and cost-effectiveness.However,challenges such as substantial volume changes and low Se utilization require f...K–Se batteries have been identified as promising energy storage systems owing to their high energy density and cost-effectiveness.However,challenges such as substantial volume changes and low Se utilization require further investigation.In this study,novel N-doped multichannel carbon nanofibers(h-NMCNFs)with hierarchical porous structures were successfully synthesized as efficient cathode hosts for K–Se batteries through the carbonization of two electrospun immiscible polymer nanofibers and subsequent chemical activation.Mesopores originated from the decomposition of the polymer embedded in the carbon nanofibers,and micropores were introduced via KOH activation.During the activation step,hierarchical porous carbon nanofibers with enhanced pore volumes were formed because of the micropores in the carbon nanofibers.Owing to the mesopores that enabled easy access to the electrolyte and the high utilization of chain-like Se within the micropores,the Se-loaded hierarchical porous carbon nanofibers(60 wt%Se)exhibited a high discharge capacity and excellent rate performance.The discharge capacity of the nanofibers at the 1,000th cycle was 210.8 mA.h.g^(-1)at a current density of 0.5C.The capacity retention after the initial activation was 64%.In addition,a discharge capacity of 165 mA.h.g^(-1)was obtained at an extremely high current density of 3.0C.展开更多
Seawater is the most abundant source of molecular hydrogen.Utilizing the hydrogen reserves present in the seawater may inaugurate innovative strategies aimed at advancing sustainable energy and environmental preservat...Seawater is the most abundant source of molecular hydrogen.Utilizing the hydrogen reserves present in the seawater may inaugurate innovative strategies aimed at advancing sustainable energy and environmental preservation endeavors in the future.Recently,there has been a surge in study in the field addressing the production of hydrogen through the electrochemical seawater splitting.However,the performance and durability of the electrode have limitations due to the fact that there are a few challenges that need to be addressed in order to make the technology suitable for the industrial purpose.The active site blockage caused by chloride ions that are prevalent in seawater and chloride corrosion is the most significant issue;it has a negative impact on both the activity and the durability of the anode component.Addressing this particular issue is of upmost importance in the seawater splitting area.This review concentrates on the newly developed materials and techniques for inhibiting chloride ions by blocking the active sites,simultaneously preventing the chloride corrosion.It is anticipated that the concept will be advantageous for a large audience and will inspire researchers to study on this particular area of concern.展开更多
Aqueous zinc-ion batteries(AZIBs)have emerged as promising,practical energy storage devices based on their non-toxic nature,environmental friendliness,and high energy density.However,excellent rate characteristics and...Aqueous zinc-ion batteries(AZIBs)have emerged as promising,practical energy storage devices based on their non-toxic nature,environmental friendliness,and high energy density.However,excellent rate characteristics and stable long-term cycling performance are essential.These essential aspects create a need for superior cathode materials,which represents a substantial challenge.In this study,we used MXenes as a framework for NH_(4)V_(4)O_(10)(NVO)construction and developed electrodes that combined the high capacity of NVO with the excellent conductivity of MXene/carbon nanofibers(MCNFs).We explored the electrochemical characteristics of electrodes with varying NVO contents.Considering the distinctive layered structure of NVO,the outstanding conductivity of MCNFs,and the strong synergies between the two components.NVO-MCNFs exhibited better charge transfer compared with earlier materials,as well as more ion storage sites,excellent conductivity,and short ion diffusion pathways.A composite electrode with optimized NVO content exhibited an excellent specific capacitance of 360.6mAh g^(-1) at 0.5 A g^(-1) and an outstanding rate performance.In particular,even at a high current density of 10 A g^(-1),the 32NVO-MCNF exhibited impressive cycling stability:88.6%over 2500 cycles.The mechanism involved was discovered via comprehensive characterization.We expect that the fabricated nanofibers will be useful in energy storage and conversion systems.展开更多
Nitrogen-doped activated carbon(N-AC)was successfully prepared by KOH-activation and nitrogen doping using ammonia(NH3)heat treatment.Coconut shell-derived activated carbon(AC)was heat-treated under NH3 gas in the tem...Nitrogen-doped activated carbon(N-AC)was successfully prepared by KOH-activation and nitrogen doping using ammonia(NH3)heat treatment.Coconut shell-derived activated carbon(AC)was heat-treated under NH3 gas in the temperature range of 700℃-900℃.Likewise,the mixture of potassium hydroxide(KOH)and AC was heated at 800℃,followed by heat treatment underNH3 gas at 800℃(hereafter referred to asKOH-N-AC800).Scanning electron microscopy(SEM),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS)and Brunauer-Emmett-Teller(BET)method were utilized to analyze morphology,crystallinity,chemical bonding,chemical composition and surface area.The surface area and porosity of N-AC increased with increasing NH3 heat treatment.Similarly,the nitrogen content in the N-AC increased from 3.23%to 4.84 at%when the NH3 heat treatment was raised from 700℃ to 800℃.However,the nitrogen content of N-AC decreased to 3.40 at% after using NH3 heat treatment at 900℃.The nitrogen content of KOH-N-AC800 is 5.43 at%.KOH-N-AC800 and N-AC800 exhibited improvements of 33.66% and 26.24%,respectively,in CO_(2) adsorption compared with AC.The enhancement of CO_(2) adsorption of KOH-N-AC800 is attributed to the synergic effect of the nitrogen doping,high surface area,and porosity.The results exhibited that nitrogen sites on the surface play a more significant role in CO_(2) adsorption than surface area and porosity.This work proposes the potential synergistic effect of KOH-activation and nitrogen doping for enhancing the CO_(2) adsorption capacity of activated carbon.展开更多
Cu/Al bar clad material was fabricated by a drawing process and a subsequent heat treatment.During these processes,intermetallic compounds have been formed at the interface of Cu/Al and have affected its bonding prope...Cu/Al bar clad material was fabricated by a drawing process and a subsequent heat treatment.During these processes,intermetallic compounds have been formed at the interface of Cu/Al and have affected its bonding property.Microstructures of Cu/Al interfaces were observed by OM,SEM and EDX Analyser in order to investigate the bonding properties of the material.According to the microstructure a series of diffusion layers were observed at the interface and the thicknesses of diffusion layers have increased with aging time as a result of the diffusion bonding.The interfaces were composed of 3-ply diffusion layers and their compositions were changed with aging time at 400 °C.These compositional compounds were revealed to be η2,(θ+η2),(α+θ) intermetallic phases.It is evident from V-notch impact tests that the growth of the brittle diffusion layers with the increasing aging time directly influenced delamination distance between the Cu sleeve and the Al core.It is suggested that the proper holding time at 400 °C for aging as post heat treatment of a drawn Cu/Al bar clad material would be within 1 h.展开更多
Understanding the material flow facilitated by tool geometry in friction stir welds is challenging for quality weld production in industrial applications.The optimal tool shoulder and pin design combination,which play...Understanding the material flow facilitated by tool geometry in friction stir welds is challenging for quality weld production in industrial applications.The optimal tool shoulder and pin design combination,which plays a vital role in material flow was addressed.The flow of plasticized material was analyzed using a marker insert technique.The results show that the knurling shoulder design with square and hexagonal pin design facilitated constant stability force with reference to weld length/time.The uniform mixing and distribution of plasticized material were facilitated by the knurling shoulder design with square tool pin shape(TK)S(sticking length minimum)below which fragmented copper was observed.(TK)S tool facilitated higher mechanical properties for the welds,i.e.strength(182 MPa)and hardness(HV 78)in stir zone.展开更多
Employing Li2CO3, NiO, Co3O4, and MnCO3 powders as starting materials, Li[Ni1/3Co1/3Mn1/3]O2 was synthesized by solid-state reaction method. Various grinding aids were applied during milling in order to optimize the s...Employing Li2CO3, NiO, Co3O4, and MnCO3 powders as starting materials, Li[Ni1/3Co1/3Mn1/3]O2 was synthesized by solid-state reaction method. Various grinding aids were applied during milling in order to optimize the synthesis process. After successive heat treatments at 650 and 950 ℃, the prepared powders were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy, and transmission electron microscopy. The powders prepared by adding salt (NaCl) as grinding aid exhibit a clear R3m layer structure. The powders by other grinding aids like heptane show some impurity peaks in the XRD pattern. The former powders show a uniform particle size distribution of less than 1 μm average size while the latter shows a wide distribution ranging from 1 to 10 μm. Energy dispersive X-ray (EDX) analysiss show that the ratio of Ni, Co, and Mn content in the powder is approximately 1/3, 1/3, and 1/3, respecively. The EDX data indicate no incorporation of sodium or chlorine into the powders. Charge-discharge tests gave an initial discharge capacity of 160 mAh·g-1 for the powders with NaCl addition while 70 mAh·g-1 for the powders with heptane.展开更多
The effects of hydro co-extrusion on the microstructure changes of aluminum hybrid duo-cast Al 3003/Al 4004 clad materials were studied. The specimen of duo-cast Al 3003/Al 4004 clad materials was in circle shape, and...The effects of hydro co-extrusion on the microstructure changes of aluminum hybrid duo-cast Al 3003/Al 4004 clad materials were studied. The specimen of duo-cast Al 3003/Al 4004 clad materials was in circle shape, and was composed of Al 3003(outside) and Al 4004(inside) materials. The specimen was extruded by the hydro co-extrusion equipment. The manufacturing conditions of the specimen were 423 K in temperature and 5 in extrusion ratio. The dimensions of the specimen were 80 mm in diameter of the Al 4004 material and 35 mm in thickness of the Al 3003 material before the hydro co-extrusion process, and 30 mm in diameter and about 5 mm in thickness after the extrusion process, respectively. The microstructure and the hardness for two specimens were investigated. The hardness value of cross section in the duo-cast Al 3003/Al 4004 clad materials before the extrusion process was increased in form of the parabola toward the center. However, after the extrusion process, it was almost constant in the portion of Al 4004 material. Lots of big voids above 1 mm in diameter in the specimen existed in the interfacing region of Al 3003 and Al 4004 materials before the extrusion process. These big voids disappeared after the process of hydro co-extrusion.展开更多
Potassium-ion batteries(PIBs)have gained significant attention as an alternative to lithium-ion batteries(LIBs)due to the abundance of potassium(K)and low cost.Nevertheless,the difficulty in finding appropriate electr...Potassium-ion batteries(PIBs)have gained significant attention as an alternative to lithium-ion batteries(LIBs)due to the abundance of potassium(K)and low cost.Nevertheless,the difficulty in finding appropriate electrode materials that can efficiently store the larger K ions has hindered their practical application.Herein,we report a novel anode material,N-doped multichannel carbon nanofibers embedded with porous CoS nanoprisms(CSP@NMCNF),for high-performance PIBs.The CSP@NMCNF was synthesized using a two-step strategy comprising of the electrospinning of Co acetate hydroxide nanoprism/binary polymer blend and a subsequent heat treatment.The porous CoS nanoprisms with an anisotropic morphology were well aligned along the length axis of the N-doped multichannel carbon nanofibers,thus ensuring their structural stability during the repeated charge-discharge process.In addition,numerous pores facilitated the transport of electrons and ions.Accordingly,the CSP@NMCNF anode exhibited excellent electrochemical performance,delivering a high specific capacity of 368 mAh·g^(-1)at 0.5 A·g^(-1)after 200 cycles and excellent rate capability(232 mAh·g^(-1)at 2.0 A·g^(-1)).展开更多
The CoCrFeMnNi high-entropy alloys(HEAs)with a(face-centered cubic) FCC structure has garnered considerable attention for its exceptional ductility and strain hardening ability.However,its yield strength is insufficie...The CoCrFeMnNi high-entropy alloys(HEAs)with a(face-centered cubic) FCC structure has garnered considerable attention for its exceptional ductility and strain hardening ability.However,its yield strength is insufficient for structural applications.In this study,strengthening mechanisms in these HEAs were investigated to gain insight into the mechanical properties according to alloy powder size.Moreover,we present a novel approach to achieve both high strength and high ductility through the creation of a bimodal structure consisting of both coarse and fine grains via gas atomization and spark plasma sintering processes.A bimodally structured HEA prepared with a mass ratio of 2:8 between coarse particles(75-106 μm) and fine particles(≤25 μm)yielded optimal results,with a strength of 491.95 MPa and elongation of 19.64%.This strength value represents an~41% increase compared with the sample that displayed a fine single microstructure(347.08 MPa for yield strength).The strength enhancement was attributed to the prevention of plastic deformation initiation from the fine particles during deformation.This innovative approach to the creation of HEAs with bimodal structures shows promise for various applications,such as structural components that require a combination of high strength and high ductility.展开更多
Developing bifunctional catalysts that can catalyze both oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is pivotal to commercializing large-scale water splitting.Herein,a novel hollow nanotriangle c...Developing bifunctional catalysts that can catalyze both oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is pivotal to commercializing large-scale water splitting.Herein,a novel hollow nanotriangle composed of NiFe LDH-CoMoS_(x) heterojunction(H-CMSx@NiFe LDH)is proposed as a highly efficient bifunctional electrocatalyst for both OER and HER.To fabricate a heterojunction system,ultra-thin nickel–iron layered double hydroxide(NiFe LDH)nanosheets are uniformly electrodeposited onto a metal–organic framework-derived hollow CoMoS_(x) nanotriangle.The strong coupling of CoMoS_(x) and NiFe LDH catalysts forms the intimate heterojunction interfaces to facilitate interfacial charge transfer,which is favorable to enhance the bifunctional catalytic activity.Moreover,the large void of CoMoS_(x) nanotriangles and interconnected ultra-thin NiFe LDH nanosheets result in good electrolyte penetration and gas release.Therefore,the as-prepared H-CMSx@NiFe LDH on nickel foam(NF)exhibits an impressive catalytic activity and durability for OER and HER activities,delivering a current density of 100 mA·cm^(−2) at the small overpotentials of 214 and 299 mV in OER and HER,respectively.Meanwhile,H-CMSx@NiFe LDH/NF proves to be an effective electrode for an alkaline electrolyzer,as a voltage of only 1.99 V is enough to achieve a current density voltage of only 1.99 V is enough to achieve a current density of 400 mA·cm^(−2) with no degradation in performance over 50 h.展开更多
The poor stability of RuO_(2)electrocatalysts has been the primary obstacles for their practical application in polymer electrolyte membrane electrolyzers.To dramatically enhance the durability of RuO_(2)to construct ...The poor stability of RuO_(2)electrocatalysts has been the primary obstacles for their practical application in polymer electrolyte membrane electrolyzers.To dramatically enhance the durability of RuO_(2)to construct activity-stability trade-off model is full of significance but challenging.Herein,a single atom Zn stabilized RuO_(2)with enriched oxygen vacancies(SA Zn-RuO_(2))is developed as a promising alternative to iridium oxide for acidic oxygen evolution reaction(OER).Compared with commercial RuO_(2),the enhanced Ru–O bond strength of SA Zn-RuO_(2)by forming Zn-O-Ru local structure motif is favorable to stabilize surface Ru,while the electrons transferred from Zn single atoms to adjacent Ru atoms protects the Ru active sites from overoxidation.Simultaneously,the optimized surrounding electronic structure of Ru sites in SA ZnRuO_(2)decreases the adsorption energies of OER intermediates to reduce the reaction barrier.As a result,the representative SA Zn-RuO_(2)exhibits a low overpotential of 210 mV to achieve 10 mA cm^(-2)and a greatly enhanced durability than commercial RuO_(2).This work provides a promising dual-engineering strategy by coupling single atom doping and vacancy for the tradeoff of high activity and catalytic stability toward acidic OER.展开更多
The lithium metal anode has emerged as a promising candidate for future high-energy-density batter-ies.However,its practical application is hindered by the uncontrollable growth of lithium dendrites.In this study,we d...The lithium metal anode has emerged as a promising candidate for future high-energy-density batter-ies.However,its practical application is hindered by the uncontrollable growth of lithium dendrites.In this study,we developed carbon nanotube(CNT)-decorated ZnO-C microspheres,containing multi-voids,as a lithiophilic host material for a stable lithium metal anode using a one-pot synthesis spray pyrolysis process.These microspheres offer ample space for accommodating lithium metal due to the presence of multi-voids.Additionally,the uniform distribution of ZnO nanocrystals and CNTs facilitates homogeneous lithium nucleation without dendrite formation.To understand the role of ZnO nanocrystals in achieving a stable lithium metal anode,density functional theory(DFT)calculations were employed,which demon-strated superior adsorption energies for lithium atoms as well as favorable electronic properties of the ZnO component.Consequently,the ZnO-C-CNT microspheres exhibit a stable lithium plating/stripping behavior,characterized by high Coulombic efficiency and the maintenance of stable voltage profiles in a symmetric cell configuration.When coupling this anode with the LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)cathode,the assem-bled full cell demonstrates excellent cycling stability and high-rate capability,indicating its potential for practical applications.展开更多
Electrocatalytic CO_(2)-to-formate conversion is considered an economically viable process.In general,Zn-based nanomaterials are well-known to be highly efficient electrocatalysts for the conversion of CO_(2)to CO,but...Electrocatalytic CO_(2)-to-formate conversion is considered an economically viable process.In general,Zn-based nanomaterials are well-known to be highly efficient electrocatalysts for the conversion of CO_(2)to CO,but seldom do they exhibit excellent selectivity toward formate.In this article,we demonstrate that a heterointerface catalyst ZnO/ZnSnO3 with nanosheet morphology shows enhanced selectivity with a maximum Faradaic efficiency(FE)of 86%at−0.9 V versus reversible hydrogen electrode and larger current density for the conversion of CO_(2)to formate than pristine ZnO and ZnSnO3.In particular,the FEs of the C1 products(CO+HCOO−)exceed 98%over the potential window.The experimental measurements combined with theoretical calculations revealed that the ZnO in ZnO/ZnSnO3 heterojunction delivers the valence electron depletion and accordingly optimizes Zn d-band center,which results in moderate Zn-O hybridization of HCOO*and weakened Zn-C hybridization of competing COOH*,thus greatly boosting the HCOOH generation.Our study highlights the importance of charge redistribution in catalysts on the selectivity of electrochemical CO_(2)reduction.展开更多
The application of Li metal anodes in rechargeable batteries is impeded by safety issues arising from the severe volume changes and formation of dendritic Li deposits.Three‐dimensional hollow carbon is receiving incr...The application of Li metal anodes in rechargeable batteries is impeded by safety issues arising from the severe volume changes and formation of dendritic Li deposits.Three‐dimensional hollow carbon is receiving increasing attention as a host material capable of accommodating Li metal inside its cavity;however,uncontrollable and nonuniform deposition of Li remains a challenge.In this study,we synthesize metal–organic framework‐derived carbon microcapsules with heteroatom clusters(Zn and Ag)on the capsule walls and it is demonstrated that Ag‐assisted nucleation of Li metal alters the outward‐to‐inward growth in the microcapsule host.Zn‐incorporated microcapsules are prepared via chemical etching of zeolitic imidazole framework‐8 polyhedra and are subsequently decorated with Ag by a galvanic displacement reaction between Ag^(+) and metallic Zn.Galvanically introduced Ag significantly reduces the energy barrier and increases the reaction rate for Li nucleation in the microcapsule host upon Li plating.Through combined electrochemical,microstructural,and computational studies,we verify the beneficial role of Ag‐assisted Li nucleation in facilitating inward growth inside the cavity of the microcapsule host and,in turn,enhancing electrochemical performance.This study provides new insights into the design of reversible host materials for practical Li metal batteries.展开更多
Recently,hollow carbon nanospheres(HCSs)have garnered significant attention as potential Li metal hosts owing to their unique large voids and ease of fabrication.However,similar to other nanoscale hosts,their practica...Recently,hollow carbon nanospheres(HCSs)have garnered significant attention as potential Li metal hosts owing to their unique large voids and ease of fabrication.However,similar to other nanoscale hosts,their practical performance is limited by inhomogeneous agglomeration,increased binder requirements,and high tortuosity within the electrode.To overcome these problems and high tortuosity within the electrode,this study introduces a pomegranate-like carbon microcluster composed of primary HCSs(P-CMs)as a novel Li metal host.This unique nanostructure can be easily prepared using the spray-drying technique,enabling its mass production.Comprehensive analyses with various tools demonstrate that compared with HCS hosts,the P-CM host requires a smaller amount of binder to fabricate a sufficiently robust and even surface electrode.Furthermore,owing to reduced tortuosity,the well-designed P-CM electrode can provide continuous and shortened pathways for electron/ion transport,accelerating the Li-ion transfer kinetics and prohibiting preferential Li plating at the upper region of the electrode.Due to these characteristics,Li metal can be effectively encapsulated in the large inner voids of the primary HCSs constituting the P-CM,thereby enhancing the electrochemical performance of P-CM hosts in Li metal batteries.Specifically,the Coulombic efficiency of the P-CM host can be maintained at 97%over 100 cycles,with a high Li deposition areal capacity of 3 mAh·cm^(-2)and long cycle life(1000 h,1 mA·cm^(-2),and 1.0 mAh·cm^(-2)).Furthermore,a full cell incorporating a LiFePO4 cathode exhibits excellent cycle life.展开更多
Microstructure and surface roughness are two critical factors governing the transparency of transparent ceramics.The manufacturing mechanism of additive manufacturing(AM)layer by layer is destined that the layer thick...Microstructure and surface roughness are two critical factors governing the transparency of transparent ceramics.The manufacturing mechanism of additive manufacturing(AM)layer by layer is destined that the layer thickness has an important influence on the microstructure and surface quality of the printed workpiece.Simultaneously,the occurrence of the stair-stepping phenomenon unavoidably results in a significant surface roughness.Therefore,in this study,yttria(Y_(2)O_(3))transparent ceramics with different printing layer thicknesses were fabricated by AM to investigate the effect of layer thickness on its optical and mechanical properties.The findings indicate that an increase in the layer thickness correlates with a heightened density in the printed green bodies,subsequently leading to enhanced transmittance in the final sintered body.When the layer thickness approximates or falls below the size of large particle agglomerations found in ceramic powders,numerous pores,and voids emerge within the green bodies.Significantly,at a layer thickness of 45µm,the in-line transmittance of Y_(2)O_(3)can reach up to 97.73%of the theoretical limit.In addition,the surface roughness of the Y_(2)O_(3)ceramics decreased as the layer thickness increased.To facilitate the further transition from translucent to transparent 3D Y_(2)O_(3)structures,a vibration-assisted chemical-mechanical polishing technique was developed by replacing water with a colloidal SiO_(2) suspension.This technique resulted in a significant reduction in the surface roughness of the Y_(2)O_(3)ceramics by 95.42%and eliminated the stair-stepping phenomenon caused by AM,thus increasing 66.12%of the in-line transmittance.These enhancements expand their potential applications in laser amplification,optical communications,and other areas requiring high-transparency materials.The method developed in this study can be used for the AM-based fabrication of transparent 3D polycrystalline ceramics.展开更多
Reducing the Ir loading while preserving catalytic performance and mechanical robustness in anodic catalyst layers remains a critical challenge for the large-scale implementation of proton exchange membrane water elec...Reducing the Ir loading while preserving catalytic performance and mechanical robustness in anodic catalyst layers remains a critical challenge for the large-scale implementation of proton exchange membrane water electrolysis(PEMWE).Herein,we present a structural engineering strategy involving neodymium-doped Ir/IrO_(2)(Nd-Ir/IrO_(2))hollow nanospheres with precisely adjustable shell thickness and cavity dimensions.The optimized catalyst demonstrates excellent oxygen evolution reaction(OER)performance in acidic media,achieving a remarkably low overpotential of 259 mV at a benchmark current density of 10 mA cm^(-2) while exhibiting substantially enhanced durability compared to commercial IrO_(2) and Ir/IrO_(2) counterparts.Notably,the Nd-Ir/IrO_(2) catalyst delivers a mass activity of 541.6 A gIr^(-1) at 1.50 V vs RHE,representing a 74.5-fold enhancement over conventional IrO_(2).Through comprehensive electrochemical analysis and advanced characterization techniques reveal that,the hierarchical hollow architecture simultaneously addresses multiple critical requirements:(i)abundant exposed active sites enabled by an enhanced electrochemical surface area,(ii)optimized mass transport pathways through engineered porosity,and(iii)preserved structural integrity via a continuous conductive framework,collectively enabling significant Ir loading reduction without compromising catalytic layer performance.Fundamental mechanistic investigations further disclose that Nd doping induces critical interfacial Nd-O-Ir configurations that stabilize lattice oxygen,together with intensified electron effect among mixed valent Ir that inhibits the overoxidation of Ir active sites during the OER process,synergistically ensuring enhanced catalytic durability.Our work establishes a dual-modulation paradigm integrating nanoscale architectural engineering with atomic-level heteroatom doping,providing a viable pathway toward high-performance PEMWE systems with drastically reduced noble metal requirements.展开更多
基金funded by Faculty of Engineering,Burapha University,grant number 003/2567.
文摘Herein,cure characteristics,morphology,and mechanical properties of natural rubber filled with activated carbon-based materials were investigated.Carbon-based materials were prepared from bagasse,coffee grounds and pineapple crowns by the pyrolysis method at temperatures in the range of 300℃.As-synthesized carbon materials were characterized by optical microscopy(OM),scanning electron microscopy(SEM),and Fourier-transform infrared spectroscopy(FTIR)to analyze size distribution,morphology,and functional groups,respectively.OM and SEM analysis revealed that particles,flakes,and a small quantity of fiber-like carbon were obtained using bagasse and pineapple crown as raw materials,while honeycomb-like carbon materials can be derived from coffee grounds.To investigate the mechanical properties,natural rubber was filled with carbon black and as-synthesized carbon materials by the internal mixing and compression molding process.Transmission electron microscopy(TEM)was utilized to characterize the dispersion of carbon materials in the rubber matrix.The results of tensile testing showed that the natural rubber mixed with as-synthesized carbon materials from pineapple crowns exhibited 54%and 74%improvement in the ultimate tensile strength and Young’s modulus,respectively,compared with natural rubber without filled carbon materials.The enhancement in mechanical properties by activated carbon materials derived from pineapple crowns can be attributed to the flake-and fiber-like structures and good dispersion of carbon materials in the rubber matrix.In addition,it is higher than that of rubber mixed with carbon black.The results demonstrated that as-synthesized carbon materials from pineapple crowns have the potential materials to substitute carbon black in the rubber compound industry.
基金financially supported by the National Research Foundation of Korea(NRF)from the Korea Government(MEST,No.NRF-2022R1F1A1070886MSIT,No.RS2023-00217581)the Commercialization Promotion Agency for R&D Outcomes(COMPA)from the Korea Government(MEST,No.1711175258)。
文摘Heteroatom-doped transition metal oxides have attracted great attention as advanced anode materials for lithium-ion batteries due to their high theoretical capacity and superior properties.However,the limited resource availability has led to a substantial rise in prices for valuable metals such as Ni and Co,posing a significant challenge for their application.To address this issue,recycling of these metals from waste materials have gained prominence,and particularly the recovery of Co has been mostly focused on its economic benefits.Herein,we introduced a novel recycling strategy for fabrication of heteroatomdoped CoO_(x)(comprising mainly Co_(3)O_(4)with a minor CoO phase)anode with a yolk–shell structure for lithium-ion batteries,by separating Co from cemented tungsten carbide waste.By employing a simple leaching process and subsequent spray pyrolysis,the yolk–shell structured microsphere comprising CoO_(x)was successfully synthesized.Moreover,the presence of other waste metals in the leachate facilitated multi-heteroatom doping during synthesis.Interestingly,the introduction of various dopants into CoO_(x)induced oxygen vacancy formation,thereby enhancing the electrochemical properties of the CoO_(x)anode.As a result,compared with the phase-pure(undoped)CoO_(x)yolk–shell,the heteroatom-doped CoO_(x)yolk–shell exhibited robust cycling stability(602 mAh·g^(-1)for 200 cycles at 1 A·g^(-1))and excellent rate capability(210 mAh·g^(-1)at 10 A·g^(-1)).
基金financially supported by the Materials/Parts Technology Development Program(No.RS-202400456324)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)by the National Research Foundation(NRF)of Korea grant(No.RS-2024-00454367)funded by the Ministry of Science and ICT(MSIT,Korea)。
文摘K–Se batteries have been identified as promising energy storage systems owing to their high energy density and cost-effectiveness.However,challenges such as substantial volume changes and low Se utilization require further investigation.In this study,novel N-doped multichannel carbon nanofibers(h-NMCNFs)with hierarchical porous structures were successfully synthesized as efficient cathode hosts for K–Se batteries through the carbonization of two electrospun immiscible polymer nanofibers and subsequent chemical activation.Mesopores originated from the decomposition of the polymer embedded in the carbon nanofibers,and micropores were introduced via KOH activation.During the activation step,hierarchical porous carbon nanofibers with enhanced pore volumes were formed because of the micropores in the carbon nanofibers.Owing to the mesopores that enabled easy access to the electrolyte and the high utilization of chain-like Se within the micropores,the Se-loaded hierarchical porous carbon nanofibers(60 wt%Se)exhibited a high discharge capacity and excellent rate performance.The discharge capacity of the nanofibers at the 1,000th cycle was 210.8 mA.h.g^(-1)at a current density of 0.5C.The capacity retention after the initial activation was 64%.In addition,a discharge capacity of 165 mA.h.g^(-1)was obtained at an extremely high current density of 3.0C.
基金supported by the Nano&Material Technology Development Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(RS-2024-00436563)supported by Brain Pool program funded by the Ministry of Science and ICT through the National Research Foundation of Korea(Grant No.RS-2023-00284361).
文摘Seawater is the most abundant source of molecular hydrogen.Utilizing the hydrogen reserves present in the seawater may inaugurate innovative strategies aimed at advancing sustainable energy and environmental preservation endeavors in the future.Recently,there has been a surge in study in the field addressing the production of hydrogen through the electrochemical seawater splitting.However,the performance and durability of the electrode have limitations due to the fact that there are a few challenges that need to be addressed in order to make the technology suitable for the industrial purpose.The active site blockage caused by chloride ions that are prevalent in seawater and chloride corrosion is the most significant issue;it has a negative impact on both the activity and the durability of the anode component.Addressing this particular issue is of upmost importance in the seawater splitting area.This review concentrates on the newly developed materials and techniques for inhibiting chloride ions by blocking the active sites,simultaneously preventing the chloride corrosion.It is anticipated that the concept will be advantageous for a large audience and will inspire researchers to study on this particular area of concern.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean Government(MSIT)(Nos.RS-2023-00217581 and RS-2023-00304768)the National Research Council of Science&Technology(NST)grant by the Korean Government(MSIT)(No.CAP 22073-000).
文摘Aqueous zinc-ion batteries(AZIBs)have emerged as promising,practical energy storage devices based on their non-toxic nature,environmental friendliness,and high energy density.However,excellent rate characteristics and stable long-term cycling performance are essential.These essential aspects create a need for superior cathode materials,which represents a substantial challenge.In this study,we used MXenes as a framework for NH_(4)V_(4)O_(10)(NVO)construction and developed electrodes that combined the high capacity of NVO with the excellent conductivity of MXene/carbon nanofibers(MCNFs).We explored the electrochemical characteristics of electrodes with varying NVO contents.Considering the distinctive layered structure of NVO,the outstanding conductivity of MCNFs,and the strong synergies between the two components.NVO-MCNFs exhibited better charge transfer compared with earlier materials,as well as more ion storage sites,excellent conductivity,and short ion diffusion pathways.A composite electrode with optimized NVO content exhibited an excellent specific capacitance of 360.6mAh g^(-1) at 0.5 A g^(-1) and an outstanding rate performance.In particular,even at a high current density of 10 A g^(-1),the 32NVO-MCNF exhibited impressive cycling stability:88.6%over 2500 cycles.The mechanism involved was discovered via comprehensive characterization.We expect that the fabricated nanofibers will be useful in energy storage and conversion systems.
基金funded by Burapha University,grant number SDG 4/2568.
文摘Nitrogen-doped activated carbon(N-AC)was successfully prepared by KOH-activation and nitrogen doping using ammonia(NH3)heat treatment.Coconut shell-derived activated carbon(AC)was heat-treated under NH3 gas in the temperature range of 700℃-900℃.Likewise,the mixture of potassium hydroxide(KOH)and AC was heated at 800℃,followed by heat treatment underNH3 gas at 800℃(hereafter referred to asKOH-N-AC800).Scanning electron microscopy(SEM),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS)and Brunauer-Emmett-Teller(BET)method were utilized to analyze morphology,crystallinity,chemical bonding,chemical composition and surface area.The surface area and porosity of N-AC increased with increasing NH3 heat treatment.Similarly,the nitrogen content in the N-AC increased from 3.23%to 4.84 at%when the NH3 heat treatment was raised from 700℃ to 800℃.However,the nitrogen content of N-AC decreased to 3.40 at% after using NH3 heat treatment at 900℃.The nitrogen content of KOH-N-AC800 is 5.43 at%.KOH-N-AC800 and N-AC800 exhibited improvements of 33.66% and 26.24%,respectively,in CO_(2) adsorption compared with AC.The enhancement of CO_(2) adsorption of KOH-N-AC800 is attributed to the synergic effect of the nitrogen doping,high surface area,and porosity.The results exhibited that nitrogen sites on the surface play a more significant role in CO_(2) adsorption than surface area and porosity.This work proposes the potential synergistic effect of KOH-activation and nitrogen doping for enhancing the CO_(2) adsorption capacity of activated carbon.
基金Project supported by the Fundamental Materials Development funded by the Korean Ministry of Knowledge Economy
文摘Cu/Al bar clad material was fabricated by a drawing process and a subsequent heat treatment.During these processes,intermetallic compounds have been formed at the interface of Cu/Al and have affected its bonding property.Microstructures of Cu/Al interfaces were observed by OM,SEM and EDX Analyser in order to investigate the bonding properties of the material.According to the microstructure a series of diffusion layers were observed at the interface and the thicknesses of diffusion layers have increased with aging time as a result of the diffusion bonding.The interfaces were composed of 3-ply diffusion layers and their compositions were changed with aging time at 400 °C.These compositional compounds were revealed to be η2,(θ+η2),(α+θ) intermetallic phases.It is evident from V-notch impact tests that the growth of the brittle diffusion layers with the increasing aging time directly influenced delamination distance between the Cu sleeve and the Al core.It is suggested that the proper holding time at 400 °C for aging as post heat treatment of a drawn Cu/Al bar clad material would be within 1 h.
文摘Understanding the material flow facilitated by tool geometry in friction stir welds is challenging for quality weld production in industrial applications.The optimal tool shoulder and pin design combination,which plays a vital role in material flow was addressed.The flow of plasticized material was analyzed using a marker insert technique.The results show that the knurling shoulder design with square and hexagonal pin design facilitated constant stability force with reference to weld length/time.The uniform mixing and distribution of plasticized material were facilitated by the knurling shoulder design with square tool pin shape(TK)S(sticking length minimum)below which fragmented copper was observed.(TK)S tool facilitated higher mechanical properties for the welds,i.e.strength(182 MPa)and hardness(HV 78)in stir zone.
基金This research was supportedby a grant under‘Development of Key Materials and Fundamental Tech-nology for Secondary Battery’Program of the Ministry of Commerce,Industry and Energy,Korea.
文摘Employing Li2CO3, NiO, Co3O4, and MnCO3 powders as starting materials, Li[Ni1/3Co1/3Mn1/3]O2 was synthesized by solid-state reaction method. Various grinding aids were applied during milling in order to optimize the synthesis process. After successive heat treatments at 650 and 950 ℃, the prepared powders were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy, and transmission electron microscopy. The powders prepared by adding salt (NaCl) as grinding aid exhibit a clear R3m layer structure. The powders by other grinding aids like heptane show some impurity peaks in the XRD pattern. The former powders show a uniform particle size distribution of less than 1 μm average size while the latter shows a wide distribution ranging from 1 to 10 μm. Energy dispersive X-ray (EDX) analysiss show that the ratio of Ni, Co, and Mn content in the powder is approximately 1/3, 1/3, and 1/3, respecively. The EDX data indicate no incorporation of sodium or chlorine into the powders. Charge-discharge tests gave an initial discharge capacity of 160 mAh·g-1 for the powders with NaCl addition while 70 mAh·g-1 for the powders with heptane.
基金supported by the project of Fundamental Materials Development funded by the Korean Ministry of Knowledge Economy
文摘The effects of hydro co-extrusion on the microstructure changes of aluminum hybrid duo-cast Al 3003/Al 4004 clad materials were studied. The specimen of duo-cast Al 3003/Al 4004 clad materials was in circle shape, and was composed of Al 3003(outside) and Al 4004(inside) materials. The specimen was extruded by the hydro co-extrusion equipment. The manufacturing conditions of the specimen were 423 K in temperature and 5 in extrusion ratio. The dimensions of the specimen were 80 mm in diameter of the Al 4004 material and 35 mm in thickness of the Al 3003 material before the hydro co-extrusion process, and 30 mm in diameter and about 5 mm in thickness after the extrusion process, respectively. The microstructure and the hardness for two specimens were investigated. The hardness value of cross section in the duo-cast Al 3003/Al 4004 clad materials before the extrusion process was increased in form of the parabola toward the center. However, after the extrusion process, it was almost constant in the portion of Al 4004 material. Lots of big voids above 1 mm in diameter in the specimen existed in the interfacing region of Al 3003 and Al 4004 materials before the extrusion process. These big voids disappeared after the process of hydro co-extrusion.
基金financially supported by a National Research Foundation of Korea(NRF)from the Korean government(MSIT)(No.2020R1C1C1003375)。
文摘Potassium-ion batteries(PIBs)have gained significant attention as an alternative to lithium-ion batteries(LIBs)due to the abundance of potassium(K)and low cost.Nevertheless,the difficulty in finding appropriate electrode materials that can efficiently store the larger K ions has hindered their practical application.Herein,we report a novel anode material,N-doped multichannel carbon nanofibers embedded with porous CoS nanoprisms(CSP@NMCNF),for high-performance PIBs.The CSP@NMCNF was synthesized using a two-step strategy comprising of the electrospinning of Co acetate hydroxide nanoprism/binary polymer blend and a subsequent heat treatment.The porous CoS nanoprisms with an anisotropic morphology were well aligned along the length axis of the N-doped multichannel carbon nanofibers,thus ensuring their structural stability during the repeated charge-discharge process.In addition,numerous pores facilitated the transport of electrons and ions.Accordingly,the CSP@NMCNF anode exhibited excellent electrochemical performance,delivering a high specific capacity of 368 mAh·g^(-1)at 0.5 A·g^(-1)after 200 cycles and excellent rate capability(232 mAh·g^(-1)at 2.0 A·g^(-1)).
基金financially supported by the Ministry of Trade,Industry&Energy (MOTIE,Korea)(No.20011520)Korea Institute of Energy Technology Evaluation and Planning (KETEP)(No.20217510100020)the Commercialization Promotion Agency for R&D Outcomes (COMPA)(No.1711175258)。
文摘The CoCrFeMnNi high-entropy alloys(HEAs)with a(face-centered cubic) FCC structure has garnered considerable attention for its exceptional ductility and strain hardening ability.However,its yield strength is insufficient for structural applications.In this study,strengthening mechanisms in these HEAs were investigated to gain insight into the mechanical properties according to alloy powder size.Moreover,we present a novel approach to achieve both high strength and high ductility through the creation of a bimodal structure consisting of both coarse and fine grains via gas atomization and spark plasma sintering processes.A bimodally structured HEA prepared with a mass ratio of 2:8 between coarse particles(75-106 μm) and fine particles(≤25 μm)yielded optimal results,with a strength of 491.95 MPa and elongation of 19.64%.This strength value represents an~41% increase compared with the sample that displayed a fine single microstructure(347.08 MPa for yield strength).The strength enhancement was attributed to the prevention of plastic deformation initiation from the fine particles during deformation.This innovative approach to the creation of HEAs with bimodal structures shows promise for various applications,such as structural components that require a combination of high strength and high ductility.
基金This work was financially supported by the National Research Foundation of Korea(NRF)from the Korean government(No.2020R1C1C1003375)Korea Institute for Advancement of Technology(KIAT)grant funded by the Korea Government(MOTIE)(No.P00124539)(HRD Program for Industrial Innovation).
文摘Developing bifunctional catalysts that can catalyze both oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is pivotal to commercializing large-scale water splitting.Herein,a novel hollow nanotriangle composed of NiFe LDH-CoMoS_(x) heterojunction(H-CMSx@NiFe LDH)is proposed as a highly efficient bifunctional electrocatalyst for both OER and HER.To fabricate a heterojunction system,ultra-thin nickel–iron layered double hydroxide(NiFe LDH)nanosheets are uniformly electrodeposited onto a metal–organic framework-derived hollow CoMoS_(x) nanotriangle.The strong coupling of CoMoS_(x) and NiFe LDH catalysts forms the intimate heterojunction interfaces to facilitate interfacial charge transfer,which is favorable to enhance the bifunctional catalytic activity.Moreover,the large void of CoMoS_(x) nanotriangles and interconnected ultra-thin NiFe LDH nanosheets result in good electrolyte penetration and gas release.Therefore,the as-prepared H-CMSx@NiFe LDH on nickel foam(NF)exhibits an impressive catalytic activity and durability for OER and HER activities,delivering a current density of 100 mA·cm^(−2) at the small overpotentials of 214 and 299 mV in OER and HER,respectively.Meanwhile,H-CMSx@NiFe LDH/NF proves to be an effective electrode for an alkaline electrolyzer,as a voltage of only 1.99 V is enough to achieve a current density voltage of only 1.99 V is enough to achieve a current density of 400 mA·cm^(−2) with no degradation in performance over 50 h.
基金supported by the Taishan Scholar Program of Shandong Province,China(tsqn202211162)the National Natural Science Foundation of China(22102079)the Natural Science Foundation of Shandong Province of China(ZR2021YQ10,ZR2022QB163)。
文摘The poor stability of RuO_(2)electrocatalysts has been the primary obstacles for their practical application in polymer electrolyte membrane electrolyzers.To dramatically enhance the durability of RuO_(2)to construct activity-stability trade-off model is full of significance but challenging.Herein,a single atom Zn stabilized RuO_(2)with enriched oxygen vacancies(SA Zn-RuO_(2))is developed as a promising alternative to iridium oxide for acidic oxygen evolution reaction(OER).Compared with commercial RuO_(2),the enhanced Ru–O bond strength of SA Zn-RuO_(2)by forming Zn-O-Ru local structure motif is favorable to stabilize surface Ru,while the electrons transferred from Zn single atoms to adjacent Ru atoms protects the Ru active sites from overoxidation.Simultaneously,the optimized surrounding electronic structure of Ru sites in SA ZnRuO_(2)decreases the adsorption energies of OER intermediates to reduce the reaction barrier.As a result,the representative SA Zn-RuO_(2)exhibits a low overpotential of 210 mV to achieve 10 mA cm^(-2)and a greatly enhanced durability than commercial RuO_(2).This work provides a promising dual-engineering strategy by coupling single atom doping and vacancy for the tradeoff of high activity and catalytic stability toward acidic OER.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MEST)(No.NRF-2022R1F1A1070886)supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.RS-2023-00217581)+1 种基金supported by the Commercialization Promotion Agency for R&D Outcomes(COMPA)grant funded by the Korean Government(Ministry of Science and ICT)(No.RS-2023-00304768)supported by the Chungbuk National University BK21 program(2023).
文摘The lithium metal anode has emerged as a promising candidate for future high-energy-density batter-ies.However,its practical application is hindered by the uncontrollable growth of lithium dendrites.In this study,we developed carbon nanotube(CNT)-decorated ZnO-C microspheres,containing multi-voids,as a lithiophilic host material for a stable lithium metal anode using a one-pot synthesis spray pyrolysis process.These microspheres offer ample space for accommodating lithium metal due to the presence of multi-voids.Additionally,the uniform distribution of ZnO nanocrystals and CNTs facilitates homogeneous lithium nucleation without dendrite formation.To understand the role of ZnO nanocrystals in achieving a stable lithium metal anode,density functional theory(DFT)calculations were employed,which demon-strated superior adsorption energies for lithium atoms as well as favorable electronic properties of the ZnO component.Consequently,the ZnO-C-CNT microspheres exhibit a stable lithium plating/stripping behavior,characterized by high Coulombic efficiency and the maintenance of stable voltage profiles in a symmetric cell configuration.When coupling this anode with the LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)cathode,the assem-bled full cell demonstrates excellent cycling stability and high-rate capability,indicating its potential for practical applications.
基金National Natural Science Foundation of China,Grant/Award Number:22102079Taishan Scholar Program of Shandong Province,China,Grant/Award Number:tsqn202211162Natural Science Foundation of Shandong Province of China,Grant/Award Numbers:ZR2021YQ10,ZR2022QB163。
文摘Electrocatalytic CO_(2)-to-formate conversion is considered an economically viable process.In general,Zn-based nanomaterials are well-known to be highly efficient electrocatalysts for the conversion of CO_(2)to CO,but seldom do they exhibit excellent selectivity toward formate.In this article,we demonstrate that a heterointerface catalyst ZnO/ZnSnO3 with nanosheet morphology shows enhanced selectivity with a maximum Faradaic efficiency(FE)of 86%at−0.9 V versus reversible hydrogen electrode and larger current density for the conversion of CO_(2)to formate than pristine ZnO and ZnSnO3.In particular,the FEs of the C1 products(CO+HCOO−)exceed 98%over the potential window.The experimental measurements combined with theoretical calculations revealed that the ZnO in ZnO/ZnSnO3 heterojunction delivers the valence electron depletion and accordingly optimizes Zn d-band center,which results in moderate Zn-O hybridization of HCOO*and weakened Zn-C hybridization of competing COOH*,thus greatly boosting the HCOOH generation.Our study highlights the importance of charge redistribution in catalysts on the selectivity of electrochemical CO_(2)reduction.
基金National Research Foundation,Grant/Award Numbers:NRF‐2018R1A5A1025594,NRF‐2022M3J1A1062644。
文摘The application of Li metal anodes in rechargeable batteries is impeded by safety issues arising from the severe volume changes and formation of dendritic Li deposits.Three‐dimensional hollow carbon is receiving increasing attention as a host material capable of accommodating Li metal inside its cavity;however,uncontrollable and nonuniform deposition of Li remains a challenge.In this study,we synthesize metal–organic framework‐derived carbon microcapsules with heteroatom clusters(Zn and Ag)on the capsule walls and it is demonstrated that Ag‐assisted nucleation of Li metal alters the outward‐to‐inward growth in the microcapsule host.Zn‐incorporated microcapsules are prepared via chemical etching of zeolitic imidazole framework‐8 polyhedra and are subsequently decorated with Ag by a galvanic displacement reaction between Ag^(+) and metallic Zn.Galvanically introduced Ag significantly reduces the energy barrier and increases the reaction rate for Li nucleation in the microcapsule host upon Li plating.Through combined electrochemical,microstructural,and computational studies,we verify the beneficial role of Ag‐assisted Li nucleation in facilitating inward growth inside the cavity of the microcapsule host and,in turn,enhancing electrochemical performance.This study provides new insights into the design of reversible host materials for practical Li metal batteries.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.2020R1C1C1003375)。
文摘Recently,hollow carbon nanospheres(HCSs)have garnered significant attention as potential Li metal hosts owing to their unique large voids and ease of fabrication.However,similar to other nanoscale hosts,their practical performance is limited by inhomogeneous agglomeration,increased binder requirements,and high tortuosity within the electrode.To overcome these problems and high tortuosity within the electrode,this study introduces a pomegranate-like carbon microcluster composed of primary HCSs(P-CMs)as a novel Li metal host.This unique nanostructure can be easily prepared using the spray-drying technique,enabling its mass production.Comprehensive analyses with various tools demonstrate that compared with HCS hosts,the P-CM host requires a smaller amount of binder to fabricate a sufficiently robust and even surface electrode.Furthermore,owing to reduced tortuosity,the well-designed P-CM electrode can provide continuous and shortened pathways for electron/ion transport,accelerating the Li-ion transfer kinetics and prohibiting preferential Li plating at the upper region of the electrode.Due to these characteristics,Li metal can be effectively encapsulated in the large inner voids of the primary HCSs constituting the P-CM,thereby enhancing the electrochemical performance of P-CM hosts in Li metal batteries.Specifically,the Coulombic efficiency of the P-CM host can be maintained at 97%over 100 cycles,with a high Li deposition areal capacity of 3 mAh·cm^(-2)and long cycle life(1000 h,1 mA·cm^(-2),and 1.0 mAh·cm^(-2)).Furthermore,a full cell incorporating a LiFePO4 cathode exhibits excellent cycle life.
基金financially supported by the Fundamental Research Program of Korea Institute of Materials Science(No.PNK9590).
文摘Microstructure and surface roughness are two critical factors governing the transparency of transparent ceramics.The manufacturing mechanism of additive manufacturing(AM)layer by layer is destined that the layer thickness has an important influence on the microstructure and surface quality of the printed workpiece.Simultaneously,the occurrence of the stair-stepping phenomenon unavoidably results in a significant surface roughness.Therefore,in this study,yttria(Y_(2)O_(3))transparent ceramics with different printing layer thicknesses were fabricated by AM to investigate the effect of layer thickness on its optical and mechanical properties.The findings indicate that an increase in the layer thickness correlates with a heightened density in the printed green bodies,subsequently leading to enhanced transmittance in the final sintered body.When the layer thickness approximates or falls below the size of large particle agglomerations found in ceramic powders,numerous pores,and voids emerge within the green bodies.Significantly,at a layer thickness of 45µm,the in-line transmittance of Y_(2)O_(3)can reach up to 97.73%of the theoretical limit.In addition,the surface roughness of the Y_(2)O_(3)ceramics decreased as the layer thickness increased.To facilitate the further transition from translucent to transparent 3D Y_(2)O_(3)structures,a vibration-assisted chemical-mechanical polishing technique was developed by replacing water with a colloidal SiO_(2) suspension.This technique resulted in a significant reduction in the surface roughness of the Y_(2)O_(3)ceramics by 95.42%and eliminated the stair-stepping phenomenon caused by AM,thus increasing 66.12%of the in-line transmittance.These enhancements expand their potential applications in laser amplification,optical communications,and other areas requiring high-transparency materials.The method developed in this study can be used for the AM-based fabrication of transparent 3D polycrystalline ceramics.
基金supported by the Taishan Scholar Program of Shandong Province,China(tsqn202211162)National Natural Science Foundation of China(22372088 and 22102079)+1 种基金Natural Science Foundation of Shandong Province of China(ZR2021YQ10)the Materials/Parts Technology Development Program(RS-2024-00432627)funded by the Ministry of Trade,Industry and Energy,Korea.
文摘Reducing the Ir loading while preserving catalytic performance and mechanical robustness in anodic catalyst layers remains a critical challenge for the large-scale implementation of proton exchange membrane water electrolysis(PEMWE).Herein,we present a structural engineering strategy involving neodymium-doped Ir/IrO_(2)(Nd-Ir/IrO_(2))hollow nanospheres with precisely adjustable shell thickness and cavity dimensions.The optimized catalyst demonstrates excellent oxygen evolution reaction(OER)performance in acidic media,achieving a remarkably low overpotential of 259 mV at a benchmark current density of 10 mA cm^(-2) while exhibiting substantially enhanced durability compared to commercial IrO_(2) and Ir/IrO_(2) counterparts.Notably,the Nd-Ir/IrO_(2) catalyst delivers a mass activity of 541.6 A gIr^(-1) at 1.50 V vs RHE,representing a 74.5-fold enhancement over conventional IrO_(2).Through comprehensive electrochemical analysis and advanced characterization techniques reveal that,the hierarchical hollow architecture simultaneously addresses multiple critical requirements:(i)abundant exposed active sites enabled by an enhanced electrochemical surface area,(ii)optimized mass transport pathways through engineered porosity,and(iii)preserved structural integrity via a continuous conductive framework,collectively enabling significant Ir loading reduction without compromising catalytic layer performance.Fundamental mechanistic investigations further disclose that Nd doping induces critical interfacial Nd-O-Ir configurations that stabilize lattice oxygen,together with intensified electron effect among mixed valent Ir that inhibits the overoxidation of Ir active sites during the OER process,synergistically ensuring enhanced catalytic durability.Our work establishes a dual-modulation paradigm integrating nanoscale architectural engineering with atomic-level heteroatom doping,providing a viable pathway toward high-performance PEMWE systems with drastically reduced noble metal requirements.
