In this work,we open an avenue toward rational design of potential efficient catalysts for sustainable ammonia synthesis through composition engineering strategy by exploiting the synergistic effects among the active ...In this work,we open an avenue toward rational design of potential efficient catalysts for sustainable ammonia synthesis through composition engineering strategy by exploiting the synergistic effects among the active sites as exemplified by diatomic metals anchored graphdiyne via the combination of hierarchical high-throughput screening,first-principles calculations,and molecular dynamics simulations.Totally 43 highly efficient catalysts feature ultralow onset potentials(|U_(onset)|≤0.40 V)with Rh-Hf and Rh-Ta showing negligible onset potentials of 0 and-0.04 V,respectively.Extremely high catalytic activities of Rh-Hf and Rh-Ta can be ascribed to the synergistic effects.When forming heteronuclears,the combinations of relatively weak(such as Rh)and relatively strong(such as Hf or Ta)components usually lead to the optimal strengths of adsorption Gibbs free energies of reaction intermediates.The origin can be ascribed to the mediate d-band centers of Rh-Hf and Rh-Ta,which lead to the optimal adsorption strengths of intermediates,thereby bringing the high catalytic activities.Our work provides a new and general strategy toward the architecture of highly efficient catalysts not only for electrocatalytic nitrogen reduction reaction(eNRR)but also for other important reactions.We expect that our work will boost both experimental and theoretical efforts in this direction.展开更多
Exploring superior calcium-magnesium-aluminosilicate(CMAS)corrosion resistance is crucial for highentropy rare-earth monosilicates(HEREMs)as the next-generation environmental barrier coating(EBC)materials.However,rela...Exploring superior calcium-magnesium-aluminosilicate(CMAS)corrosion resistance is crucial for highentropy rare-earth monosilicates(HEREMs)as the next-generation environmental barrier coating(EBC)materials.However,related studies are rarely reported.This work presents the exploration of HEREMs with remarkable CMAS corrosion resistance by engineering their compositions.The equimolar 3-to-9 cation high-entropy rare-earth monosilicate(3-9HEREM)specimens were initially prepared using a pressure-less sintering technique;subsequently,their resistance to CMAS corrosion was evaluated at temperatures up to 1600C.The results demonstrate that the 5HEREM specimens possess the best CMAS corrosion resistance among all the as-fabricated specimens,surpassing other reported EBC materials.Such remarkable CMAS corrosion resistance results from the generation of a dense apatite protective layer originating from its low dissolution rate at elevated temperatures.展开更多
Microwave absorbing materials(MAMs)characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications.Both silicon carbide and carbon are considered as stable M...Microwave absorbing materials(MAMs)characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications.Both silicon carbide and carbon are considered as stable MAMs under some rigorous conditions,while their composites still fail to produce satisfactory microwave absorption performance regardless of the improvements as compared with the individuals.Herein,we have successfully implemented compositional and structural engineering to fabricate hollow Si C/C microspheres with controllable composition.The simultaneous modulation on dielectric properties and impedance matching can be easily achieved as the change in the composition of these composites.The formation of hollow structure not only favors lightweight feature,but also generates considerable contribution to microwave attenuation capacity.With the synergistic effect of composition and structure,the optimized SiC/C composite exhibits excellent performance,whose the strongest reflection loss intensity and broadest effective absorption reach-60.8 dB and 5.1 GHz,respectively,and its microwave absorption properties are actually superior to those of most SiC/C composites in previous studies.In addition,the stability tests of microwave absorption capacity after exposure to harsh conditions and Radar Cross Section simulation data demonstrate that hollow SiC/C microspheres from compositional and structural optimization have a bright prospect in practical applications.展开更多
Metal halide perovskites have received considerable attention in the field of electroluminescence,and the external quantum efficiency of perovsk'c lightemitting diodes has exceeded 20%.CH3NH3PbBr3 has been intense...Metal halide perovskites have received considerable attention in the field of electroluminescence,and the external quantum efficiency of perovsk'c lightemitting diodes has exceeded 20%.CH3NH3PbBr3 has been intensely investigated as an emitting layer in perovskite light-emitting diodes.However,perovskite films comprising CH3NH3PbBr3 often exhibit low surface coverage and poor crystallinity,leading to high current leakage,severe nonradiative recombination,and limited device performance.Herein,we demonstrate a rationale for composition engineering to obtain high-quality perovskite films.We first reduce pinholes by adding excess CH3NH3B1 to the actual CH3NH3PbBr3 films,and we then add CsBr to improve the crystalline quality and to passivate nonradiative defects.As a result,the(CH3NH3)1-xCSxPbBx based perovskite light-emitting diodes exhibit significantly improved external quantum and power efficiencies of 6.97%and 25.181m/W,respectively,representing an improvement in performance dozens of times greater than that of pristine CH3NH3PbBr3-based perovskite light-emitting diodes.Our study demonstrates that composition engineering is an effective strategy for enhancing the device performance of perovskite light-emitting diodes.展开更多
In this research highlight,recent significant advances with hot-assisted blade-coating or air knife-assisted blade-coating of different perovskite compositions with bandgaps ranging from 1.3 eV to 1.9 eV(i.e.widebandg...In this research highlight,recent significant advances with hot-assisted blade-coating or air knife-assisted blade-coating of different perovskite compositions with bandgaps ranging from 1.3 eV to 1.9 eV(i.e.widebandgap or small-bandgap perovskites with mixed cations and anions,2D/3D perovskites,Pb/Sn binary perovskites,and all-inorganic perovskites)for single-junction or tandem PSCs are discussed,with an emphasis on elucidating the distinct ink formulation engineering strategies,crystal growth mechanisms,crystallization kinetics,and optoelectronic properties of the different perovskite compositions.展开更多
Practical applications of desulfurization gypsum are limited owing to its brittleness and low strength.To overcome these challenges,researchers have developed engineered desulfurization gypsum composites(EDGCs)by inco...Practical applications of desulfurization gypsum are limited owing to its brittleness and low strength.To overcome these challenges,researchers have developed engineered desulfurization gypsum composites(EDGCs)by incorporating ultrahigh molecular weight polyethylene(UHMWPE)fiber and sulfoaluminate cement(SAC).The mix ratio was optimized using response surface methodology(RSM).Experimental testing of EDGC under compressive and tensile loads led to the creation of a regression model that investigates the influence of variables and their interactions on the material’s compressive and tensile strengths.Additionally,microscopic morphology and hydration product composition were analyzed to explore the influence mechanism.The results indicated that EDGC’s compressive strength increased by up to 38.4%owing to a decreased water-binder ratio and higher SAC content.Similarly,tensile strength increased by up to 38.6%owing to increased SAC and fiber content.Moreover,EDGC demonstrated excellent strain-hardening behavior and multiple cracking characteristics,achieving a maximum tensile strain of nearly 3%.The research findings provide valuable insights for optimizing the performance of desulfurization gypsum.展开更多
Inhibition measurement of shrinkage of engineering cementitious composites （ECC） was investigated due to typical ECC with higher free drying shrinkage.The effects of expanded admixture （EA）,shrinkage reducing admi...Inhibition measurement of shrinkage of engineering cementitious composites （ECC） was investigated due to typical ECC with higher free drying shrinkage.The effects of expanded admixture （EA）,shrinkage reducing admixture （SRA）,coarse sand＋stone powder （CS＋SP） and superabsorbent polymer （SAP） on drying shrinkage and mechanical properties were studied.The experimental results show that ECC incorporating EA,SRA and coarse sand can retain around 60% of the typical ECC＇s free drying shrinkage.Superabsorbent polymerl（SAP） can delay the development of free drying shrinkage of ECC at different ages,and the effect of SAP is not distinct like the actions of EA,superabsorbent polymer（SRA） and coarse sand.Significantly,SAP may act as artificial flaw to form a more homogeneous defect system that increases the potential of saturated multiple cracking,hence the ductility of ECC will be improved greatly.展开更多
Metal(Li,Na,K,Al)-ion batteries and lithium-sulfur and lithium-tellurium batteries are gaining recognition for their eco-friendly characteristics,substantial energy density,and sustainable attributes.However,the overa...Metal(Li,Na,K,Al)-ion batteries and lithium-sulfur and lithium-tellurium batteries are gaining recognition for their eco-friendly characteristics,substantial energy density,and sustainable attributes.However,the overall performance of rechargeable batteries heavily depends on their electrode materials.Transition metal tellurides have recently gained significant attention due to their high electrical conductivity and density.Cobalt telluride has received the most extensive research due to its catalytic activity,unique magnetic properties,and diverse composition and crystal structure.Nevertheless,its limited conductivity and significant volume variation contribute to electrode structural deterioration and rapid capacity decline.This review comprehensively summarizes recent advances in rational design and synthesis of modified cobalt telluride-based electrodes,encompassing defect engineering(Te vacancies,cation vacancies,heterointerfaces,and homogeneous interfaces)and composite engineering(derived carbon from precursors,carbon fibers,Mxene,graphene nanosheets,etc.).Particularly,the intricate evolution mechanisms of the conversion reaction process during cycling are elucidated.Furthermore,these modified strategies applied to other transitional metal tellurides,such as iron telluride,nickel telluride,zinc telluride,copper telluride,molybdenum telluride,etc.,are also thoroughly summarized.Additionally,their application extends to emerging aqueous zinc-ion batteries.Finally,potential challenges and prospects are discussed to further propel the development of transition metal tellurides electrode materials for next-generation rechargeable batteries.展开更多
Plain concrete is strong in compression but brittle in tension,having a low tensile strain capacity that can significantly degrade the long-term performance of concrete structures,even when steel reinforcing is presen...Plain concrete is strong in compression but brittle in tension,having a low tensile strain capacity that can significantly degrade the long-term performance of concrete structures,even when steel reinforcing is present.In order to address these challenges,short polymer fibers are randomly dispersed in a cement-based matrix to forma highly ductile engineered cementitious composite(ECC).Thismaterial exhibits high ductility under tensile forces,with its tensile strain being several hundred times greater than conventional concrete.Since concrete is inherently weak in tension,the tensile strain capacity(TSC)has become one of the most extensively researched properties.As a result,developing a model to predict the TSC of the ECC and to optimize the mixture proportions becomes challenging.Meanwhile,the effort required for laboratory trial batches to determine the TSC is reduced.To achieve the research objectives,five distinct models,artificial neural network(ANN),nonlinear model(NLR),linear relationship model(LR),multi-logistic model(MLR),and M5P-tree model(M5P),are investigated and employed to predict the TSCof ECCmixtures containing fly ash.Data from115 mixtures are gathered and analyzed to develop a new model.The input variables include mixture proportions,fiber length and diameter,and the time required for curing the various mixtures.The model’s effectiveness is evaluated and verified based on statistical parameters such as R2,mean absolute error(MAE),scatter index(SI),root mean squared error(RMSE),and objective function(OBJ)value.Consequently,the ANN model outperforms the others in predicting the TSC of the ECC,with RMSE,MAE,OBJ,SI,and R2 values of 0.42%,0.3%,0.33%,0.135%,and 0.98,respectively.展开更多
The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolyme...The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and construction.However,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain.In this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and flexure.The experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of fibers.After that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements.The tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion.It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios.For AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly reduced.For plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.展开更多
In this paper,the degradation of mechanical properties of engineering cementitious composites(ECCs)at elevated temperatures and the failure of fiber are considered.A failure model under coupled thermo-mechanical loads...In this paper,the degradation of mechanical properties of engineering cementitious composites(ECCs)at elevated temperatures and the failure of fiber are considered.A failure model under coupled thermo-mechanical loads for ECC is developed based on bond-based peridynamics.A semi-discrete model is constructed to describe fiber–matrix interactions and simulate thermal failure in ECC.The peridynamic differential operator(PDDO)is utilized for non-local modeling of thermal fluid flow and heat transfer.A multi-rate explicit time integration method is adopted to address thermo-mechanical coupling over different time scales.Model validation is achieved through simulating transient heat transfer in a homogeneous plate,with results aligning with analytical solutions.The damage behavior of a heated ECC plate in a borehole and under a fire scenario is analyzed,providing insights for enhancing fire resistance and high-temperature performance of ECC materials and structures.展开更多
To investigate the flexural behaviors of steel reinforced engineered cementitious composite （ECC） beams, the behaviors of the steel reinforced ECC beam and the conventional steel reinforced concrete beam subjected t...To investigate the flexural behaviors of steel reinforced engineered cementitious composite （ECC） beams, the behaviors of the steel reinforced ECC beam and the conventional steel reinforced concrete beam subjected to flexural load are experimentally compared. The experimental results show that the flexural strength and ductility of the steel reinforced ECC beam are 24.8% and 187.67% times larger than those of the steel reinforced concrete beam, and the substitution of concrete with ECC can significantly delay the propagation of cracks. Additionally, a simplified constitutive model of the ECC material is used to simulate the flexural behaviors of beams by the finite element analysis （FEA）. The results show a good agreement between the simulation and test results. The crack width of the steel reinforced ECC beam can be limited to 0.4 mm under the service load conditions. The application of ductile ECC can significantly increase the flexural performance in terms of flexural strength, deformation capacity and ductility of the beams.展开更多
In order to reduce the cost of high performance polyvinyl alcohol（PVA） fiber reinforced cementitious material（called engineered cementitious composites,ECC）,a ductile ECC material is developed using domestic PVA f...In order to reduce the cost of high performance polyvinyl alcohol（PVA） fiber reinforced cementitious material（called engineered cementitious composites,ECC）,a ductile ECC material is developed using domestic PVA fibers along with other local ingredients,such as fly ash,cement and sand.In addition to the economic analysis of ECC,the four-point bending test and the optical microscope are employed to investigate the deflection capacity of ECC,its crack width and the occurrence of the self-healing phenomenon.The experimental results suggest that ECC made with domestic ingredients exhibits larger deformability and the average crack width is controlled around 60 μm.Furthermore,the self-healing behavior is observed in cracks of the specimens after cycles of wet and dry curing.The economic analysis shows that the cost of ECC can be greatly reduced via employing domestic PVA fibers.It is,therefore,feasible to produce low cost ECC material employing domestic PVA fibers,while simultaneously retaining high material ductility.展开更多
In order to avoid brittle fracture failure, a ductile engineered cementitious composite （ECC） was attempted in steel/concrete connection zones to replace normal concrete. The influence of the ECC material ductility ...In order to avoid brittle fracture failure, a ductile engineered cementitious composite （ECC） was attempted in steel/concrete connection zones to replace normal concrete. The influence of the ECC material ductility on connection failure modes and structural performance was investigated via the pushout test of stud/ECC connection, the pullout test of two-dimensional anchor bolt/ECC connection and the finite element modeling （FEM）. The experimental results suggest that the micromechanically designed ECC with a tensile ductility 300 times that of normal concrete switches the brittle fracture failure mode to a ductile one in steel connection zones. This modification in material behavior leads to higher load carrying capacity and structural ductility, which is also confirmed in FEM investigation. The enhancement in structural response through material ductility engineering is expected to be applicable to a wide range of engineering structures where steel and concrete come into contact.展开更多
Blue photodetectors(PDs)are attracting great attention for various applications.Commercial blue PDs based on inorganic GaP or InGaN absorbers are limited by their expensive,complex,and high-temperature fabrication tec...Blue photodetectors(PDs)are attracting great attention for various applications.Commercial blue PDs based on inorganic GaP or InGaN absorbers are limited by their expensive,complex,and high-temperature fabrication techniques.Organic absorber-based blue PDs still have much lower photode-tecting properties than inorganic blue PDs.In this study,a high-performance self-powered blue PD is developed using methylammonium lead halide(MAPbX_(3);X=I,Br,and Cl)perovskites based on the eco-nomic and facile solution process at low temperatures.Optimal composition is obtained through halide-composition engineering.Our best-performing device exhibits an average external quantum efficiency and an average detectivity of 42.7%and 8.65×10^(11) Jones,respectively,within the blue region.The peak responsivity of the proposed PD is 0.174 A W^(−1) at 455 nm,which is comparable to that of commercial gallium phosphide blue PD(0.180 A W^(−1) at 470 nm).Moreover,the proposed device exhibits excellent environmental stability under ambient air conditions.These findings will act as a basis for next-generation image sensor technologies,such as vertically stacked red/green/blue PDs.展开更多
Exploiting high-efficiency Ni-based materials for electrocatalytic urea oxidation reaction(UOR) is critical for urea-related technologies.The catalytic site density,intrinsic activity,charge transfer,and mass diffusio...Exploiting high-efficiency Ni-based materials for electrocatalytic urea oxidation reaction(UOR) is critical for urea-related technologies.The catalytic site density,intrinsic activity,charge transfer,and mass diffusion determine overall electrocatalytic efficiency.Simultaneous modulation over the above four factors promises advanced electrocatalysis,yet challenging.Herein we propose a systematic regulation tactic over composition and geometric structure,constructing a nanocomposite comprising Mn doped Ni_(3)N nanoparticles anchored on reduced graphene oxide(rGO/Mn-Ni_(3)N),achieving elegant integration of four design principles into one,thereby eminently boosting UOR.Particularly,Mn doping in Ni_(3)N can modulate electronic state to induce intrinsic activity regulation.Combining metallic Mn-Ni_(3)N with rGO to engineer hierarchical architecture not only promotes charge transfer,but also enriches active site population.Intriguingly,improved hydrophilicity could impart better electrolyte penetration and gas escape.Consequently,such system-optimized rGO/Mn-Ni_(3)N demonstrates state-of-the-art-level UOR electrocatalysis.This work offers a novel paradigm to create advanced catalysts via systematic and integrated modulation.展开更多
Perovskite quantum-dots (PQDs) have emerged as prominent candidates for intriguing photovoltaic application due to their superior optoelectronic properties such as multiple exciton generation, bandgap tunability, elec...Perovskite quantum-dots (PQDs) have emerged as prominent candidates for intriguing photovoltaic application due to their superior optoelectronic properties such as multiple exciton generation, bandgap tunability, electronic and surface chemistry properties, as well as flexible composition [1–5].展开更多
An engineered cementitious composite （ECC） is introduced to partially substitute concrete in the tension zone of a reinforced concrete beam to form an ECC/reinforced concrete （RC） composite beam, which can increas...An engineered cementitious composite （ECC） is introduced to partially substitute concrete in the tension zone of a reinforced concrete beam to form an ECC/reinforced concrete （RC） composite beam, which can increase the ductility and crack resisting ability of the beam. Based on the assumption of the plane remaining plane and the simplified constitutive models of materials, the stress and strain distributions along the depth of the composite beam in different loading stages are comprehensively investigated to obtain calculation methods of the load-carrying capacities for different stages. Also, a simplified formula for the ultimate load carrying capacity is proposed according to the Chinese code for the design of concrete structures. The relationship between the moment and curvature for the composite beam is also proposed together with a simplified calculation method for ductility of the ECC/RC composite beam. Finally, the calculation method is demonstrated with the test results of a composite beam. Comparison results show that the calculation results have good consistency with the test results, proving that the proposed calculation methods are reliable with a certain theoretical significance and reference value.展开更多
In order to investigate the flexural behaviors of engineered cementitious composites （ECC）, theoretical and experimental researches are done on flexural doublereinforced ECC beams. Based on the assumption of the pla...In order to investigate the flexural behaviors of engineered cementitious composites （ECC）, theoretical and experimental researches are done on flexural doublereinforced ECC beams. Based on the assumption of the plane section remaining plane in bending and simplified constitutive models of materials, the calculation methods of load carrying capacities for different critical stages are obtained. Then, these calculation methods are demonstrated by comparing the test results with the calculation results. Finally, based on the proposed theoretical formulae, the effects of the compression strength, compression strain and tension strength of ECC, and the reinforcement ratio on the flexural behaviors of double-reinforced ECC beams are analyzed. The calculated and measured results are in good agreement, which indicates that the theoretical model can be used to predict the momentcurvature response of steel reinforced ECC beams. And the results of parametric studies show that the increase in the compression strength of ECC can greatly improve the flexural performance of beams; the increase in the ultimate compression strain can significantly improve the ultimate curvature and ductility, but has little effect on the load bearing capacity of beams. little effect on the flexural The tensile strength of ECC has behaviors of ECC beams. The increase in the steel reinforcement ratio can lead to significant improvement of the load bearing capacity and the stiffness of beams, but a degradation of the ductility of beams. The theoretical model and parameter analysis results in this paper are instructive for the design of steel reinforced ECC beams.展开更多
基金support from the National Natural Science Foundation of China(22073033,21873032,21673087,21903032)startup fund(2006013118 and 3004013105)from Huazhong University of Science and Technology+1 种基金the Fundamental Research Funds for the Central Universities(2019kfyRCPY116)the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003)
文摘In this work,we open an avenue toward rational design of potential efficient catalysts for sustainable ammonia synthesis through composition engineering strategy by exploiting the synergistic effects among the active sites as exemplified by diatomic metals anchored graphdiyne via the combination of hierarchical high-throughput screening,first-principles calculations,and molecular dynamics simulations.Totally 43 highly efficient catalysts feature ultralow onset potentials(|U_(onset)|≤0.40 V)with Rh-Hf and Rh-Ta showing negligible onset potentials of 0 and-0.04 V,respectively.Extremely high catalytic activities of Rh-Hf and Rh-Ta can be ascribed to the synergistic effects.When forming heteronuclears,the combinations of relatively weak(such as Rh)and relatively strong(such as Hf or Ta)components usually lead to the optimal strengths of adsorption Gibbs free energies of reaction intermediates.The origin can be ascribed to the mediate d-band centers of Rh-Hf and Rh-Ta,which lead to the optimal adsorption strengths of intermediates,thereby bringing the high catalytic activities.Our work provides a new and general strategy toward the architecture of highly efficient catalysts not only for electrocatalytic nitrogen reduction reaction(eNRR)but also for other important reactions.We expect that our work will boost both experimental and theoretical efforts in this direction.
基金the National Key Research and Development Program of China(No.2022YFB3708600)the National Natural Science Foundation of China(No.52122204).
文摘Exploring superior calcium-magnesium-aluminosilicate(CMAS)corrosion resistance is crucial for highentropy rare-earth monosilicates(HEREMs)as the next-generation environmental barrier coating(EBC)materials.However,related studies are rarely reported.This work presents the exploration of HEREMs with remarkable CMAS corrosion resistance by engineering their compositions.The equimolar 3-to-9 cation high-entropy rare-earth monosilicate(3-9HEREM)specimens were initially prepared using a pressure-less sintering technique;subsequently,their resistance to CMAS corrosion was evaluated at temperatures up to 1600C.The results demonstrate that the 5HEREM specimens possess the best CMAS corrosion resistance among all the as-fabricated specimens,surpassing other reported EBC materials.Such remarkable CMAS corrosion resistance results from the generation of a dense apatite protective layer originating from its low dissolution rate at elevated temperatures.
基金supported by the National Natural Science Foundation of China(No.21676065 and No.52373262)China Postdoctoral Science Foundation(2021MD703944,2022T150782).
文摘Microwave absorbing materials(MAMs)characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications.Both silicon carbide and carbon are considered as stable MAMs under some rigorous conditions,while their composites still fail to produce satisfactory microwave absorption performance regardless of the improvements as compared with the individuals.Herein,we have successfully implemented compositional and structural engineering to fabricate hollow Si C/C microspheres with controllable composition.The simultaneous modulation on dielectric properties and impedance matching can be easily achieved as the change in the composition of these composites.The formation of hollow structure not only favors lightweight feature,but also generates considerable contribution to microwave attenuation capacity.With the synergistic effect of composition and structure,the optimized SiC/C composite exhibits excellent performance,whose the strongest reflection loss intensity and broadest effective absorption reach-60.8 dB and 5.1 GHz,respectively,and its microwave absorption properties are actually superior to those of most SiC/C composites in previous studies.In addition,the stability tests of microwave absorption capacity after exposure to harsh conditions and Radar Cross Section simulation data demonstrate that hollow SiC/C microspheres from compositional and structural optimization have a bright prospect in practical applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.51802102,21805101,and 51902110)Natural Science Foundation of Fujian Province(No.2019J01057)+1 种基金Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University(No.ZQN-PY607)Scientific Research Funds of Huaqiao University(Nos.16BS201,17BS409,and 19BS105).
文摘Metal halide perovskites have received considerable attention in the field of electroluminescence,and the external quantum efficiency of perovsk'c lightemitting diodes has exceeded 20%.CH3NH3PbBr3 has been intensely investigated as an emitting layer in perovskite light-emitting diodes.However,perovskite films comprising CH3NH3PbBr3 often exhibit low surface coverage and poor crystallinity,leading to high current leakage,severe nonradiative recombination,and limited device performance.Herein,we demonstrate a rationale for composition engineering to obtain high-quality perovskite films.We first reduce pinholes by adding excess CH3NH3B1 to the actual CH3NH3PbBr3 films,and we then add CsBr to improve the crystalline quality and to passivate nonradiative defects.As a result,the(CH3NH3)1-xCSxPbBx based perovskite light-emitting diodes exhibit significantly improved external quantum and power efficiencies of 6.97%and 25.181m/W,respectively,representing an improvement in performance dozens of times greater than that of pristine CH3NH3PbBr3-based perovskite light-emitting diodes.Our study demonstrates that composition engineering is an effective strategy for enhancing the device performance of perovskite light-emitting diodes.
基金the financial supports from the National Key R&D Program of China(2019YFB1503200)the GDUPS(2016)+4 种基金the NSF of Guangdong Province(2019B1515120050)the Fundamental Research Funds for the Central Universities(19lgjc07)the financial support from the Guangdong Basic and Applied Basic Research Foundation(2019A1515110770)National Key Research and Development Program of China(2017YFA0206600)National Natural Science Foundation of China(51773045,21772030,51922032,21961160720)for financial support
文摘In this research highlight,recent significant advances with hot-assisted blade-coating or air knife-assisted blade-coating of different perovskite compositions with bandgaps ranging from 1.3 eV to 1.9 eV(i.e.widebandgap or small-bandgap perovskites with mixed cations and anions,2D/3D perovskites,Pb/Sn binary perovskites,and all-inorganic perovskites)for single-junction or tandem PSCs are discussed,with an emphasis on elucidating the distinct ink formulation engineering strategies,crystal growth mechanisms,crystallization kinetics,and optoelectronic properties of the different perovskite compositions.
基金The National Natural Science Foundation of China(No.51978504).
文摘Practical applications of desulfurization gypsum are limited owing to its brittleness and low strength.To overcome these challenges,researchers have developed engineered desulfurization gypsum composites(EDGCs)by incorporating ultrahigh molecular weight polyethylene(UHMWPE)fiber and sulfoaluminate cement(SAC).The mix ratio was optimized using response surface methodology(RSM).Experimental testing of EDGC under compressive and tensile loads led to the creation of a regression model that investigates the influence of variables and their interactions on the material’s compressive and tensile strengths.Additionally,microscopic morphology and hydration product composition were analyzed to explore the influence mechanism.The results indicated that EDGC’s compressive strength increased by up to 38.4%owing to a decreased water-binder ratio and higher SAC content.Similarly,tensile strength increased by up to 38.6%owing to increased SAC and fiber content.Moreover,EDGC demonstrated excellent strain-hardening behavior and multiple cracking characteristics,achieving a maximum tensile strain of nearly 3%.The research findings provide valuable insights for optimizing the performance of desulfurization gypsum.
基金Funded by the National Natural Science Foundation of China (No.50872127)Heilongjiang Provincial Scientific Research Foundation for Returned Overseas Scholars
文摘Inhibition measurement of shrinkage of engineering cementitious composites （ECC） was investigated due to typical ECC with higher free drying shrinkage.The effects of expanded admixture （EA）,shrinkage reducing admixture （SRA）,coarse sand＋stone powder （CS＋SP） and superabsorbent polymer （SAP） on drying shrinkage and mechanical properties were studied.The experimental results show that ECC incorporating EA,SRA and coarse sand can retain around 60% of the typical ECC＇s free drying shrinkage.Superabsorbent polymerl（SAP） can delay the development of free drying shrinkage of ECC at different ages,and the effect of SAP is not distinct like the actions of EA,superabsorbent polymer（SRA） and coarse sand.Significantly,SAP may act as artificial flaw to form a more homogeneous defect system that increases the potential of saturated multiple cracking,hence the ductility of ECC will be improved greatly.
基金financially supported by the National Natural Science Foundation of China (Nos.52171202,52177208,52071073)the financial support from CSIRO+3 种基金the Department of Climate Change,Energy,the Environment and Water (DCCEEW)Australian Governmentthe Australian Hydrogen Research Network (AHRN)the Australian Research Council (DE230100327 and LP220200583)the support from the DCCEEW International Clean Innovation Researcher Networks Grant (ICIRN000011)。
文摘Metal(Li,Na,K,Al)-ion batteries and lithium-sulfur and lithium-tellurium batteries are gaining recognition for their eco-friendly characteristics,substantial energy density,and sustainable attributes.However,the overall performance of rechargeable batteries heavily depends on their electrode materials.Transition metal tellurides have recently gained significant attention due to their high electrical conductivity and density.Cobalt telluride has received the most extensive research due to its catalytic activity,unique magnetic properties,and diverse composition and crystal structure.Nevertheless,its limited conductivity and significant volume variation contribute to electrode structural deterioration and rapid capacity decline.This review comprehensively summarizes recent advances in rational design and synthesis of modified cobalt telluride-based electrodes,encompassing defect engineering(Te vacancies,cation vacancies,heterointerfaces,and homogeneous interfaces)and composite engineering(derived carbon from precursors,carbon fibers,Mxene,graphene nanosheets,etc.).Particularly,the intricate evolution mechanisms of the conversion reaction process during cycling are elucidated.Furthermore,these modified strategies applied to other transitional metal tellurides,such as iron telluride,nickel telluride,zinc telluride,copper telluride,molybdenum telluride,etc.,are also thoroughly summarized.Additionally,their application extends to emerging aqueous zinc-ion batteries.Finally,potential challenges and prospects are discussed to further propel the development of transition metal tellurides electrode materials for next-generation rechargeable batteries.
文摘Plain concrete is strong in compression but brittle in tension,having a low tensile strain capacity that can significantly degrade the long-term performance of concrete structures,even when steel reinforcing is present.In order to address these challenges,short polymer fibers are randomly dispersed in a cement-based matrix to forma highly ductile engineered cementitious composite(ECC).Thismaterial exhibits high ductility under tensile forces,with its tensile strain being several hundred times greater than conventional concrete.Since concrete is inherently weak in tension,the tensile strain capacity(TSC)has become one of the most extensively researched properties.As a result,developing a model to predict the TSC of the ECC and to optimize the mixture proportions becomes challenging.Meanwhile,the effort required for laboratory trial batches to determine the TSC is reduced.To achieve the research objectives,five distinct models,artificial neural network(ANN),nonlinear model(NLR),linear relationship model(LR),multi-logistic model(MLR),and M5P-tree model(M5P),are investigated and employed to predict the TSCof ECCmixtures containing fly ash.Data from115 mixtures are gathered and analyzed to develop a new model.The input variables include mixture proportions,fiber length and diameter,and the time required for curing the various mixtures.The model’s effectiveness is evaluated and verified based on statistical parameters such as R2,mean absolute error(MAE),scatter index(SI),root mean squared error(RMSE),and objective function(OBJ)value.Consequently,the ANN model outperforms the others in predicting the TSC of the ECC,with RMSE,MAE,OBJ,SI,and R2 values of 0.42%,0.3%,0.33%,0.135%,and 0.98,respectively.
基金National Natural Science Foundation of China(Grant Nos.51908188 and 51938011).
文摘The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and construction.However,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain.In this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and flexure.The experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of fibers.After that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements.The tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion.It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios.For AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly reduced.For plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.
基金supported by National Natural Science Foundation of China(Grant Numbers 11872339,11472248).
文摘In this paper,the degradation of mechanical properties of engineering cementitious composites(ECCs)at elevated temperatures and the failure of fiber are considered.A failure model under coupled thermo-mechanical loads for ECC is developed based on bond-based peridynamics.A semi-discrete model is constructed to describe fiber–matrix interactions and simulate thermal failure in ECC.The peridynamic differential operator(PDDO)is utilized for non-local modeling of thermal fluid flow and heat transfer.A multi-rate explicit time integration method is adopted to address thermo-mechanical coupling over different time scales.Model validation is achieved through simulating transient heat transfer in a homogeneous plate,with results aligning with analytical solutions.The damage behavior of a heated ECC plate in a borehole and under a fire scenario is analyzed,providing insights for enhancing fire resistance and high-temperature performance of ECC materials and structures.
基金The National Natural Science Foundation of China(No.51278118)the National Basic Research Program of China(973Program)(No.2009CB623200)the Natural Science Foundation of Jiangsu Province(No.BK2012756)
文摘To investigate the flexural behaviors of steel reinforced engineered cementitious composite （ECC） beams, the behaviors of the steel reinforced ECC beam and the conventional steel reinforced concrete beam subjected to flexural load are experimentally compared. The experimental results show that the flexural strength and ductility of the steel reinforced ECC beam are 24.8% and 187.67% times larger than those of the steel reinforced concrete beam, and the substitution of concrete with ECC can significantly delay the propagation of cracks. Additionally, a simplified constitutive model of the ECC material is used to simulate the flexural behaviors of beams by the finite element analysis （FEA）. The results show a good agreement between the simulation and test results. The crack width of the steel reinforced ECC beam can be limited to 0.4 mm under the service load conditions. The application of ductile ECC can significantly increase the flexural performance in terms of flexural strength, deformation capacity and ductility of the beams.
基金The National Natural Science Foundation of China (No.51008071,51278097)the Natural Science Foundation of Jiangsu Province(No.BK2010413)+2 种基金Teaching & Research Excellence Grant for Young Faculty Member at Southeast Universitythe Program for Special Talents in Six Major Fields of Jiangsu Province(No.2011-JZ-011)the Scientific Research Innovation Project for College Graduates in Jiangsu Province(No.CXLX_0136)
文摘In order to reduce the cost of high performance polyvinyl alcohol（PVA） fiber reinforced cementitious material（called engineered cementitious composites,ECC）,a ductile ECC material is developed using domestic PVA fibers along with other local ingredients,such as fly ash,cement and sand.In addition to the economic analysis of ECC,the four-point bending test and the optical microscope are employed to investigate the deflection capacity of ECC,its crack width and the occurrence of the self-healing phenomenon.The experimental results suggest that ECC made with domestic ingredients exhibits larger deformability and the average crack width is controlled around 60 μm.Furthermore,the self-healing behavior is observed in cracks of the specimens after cycles of wet and dry curing.The economic analysis shows that the cost of ECC can be greatly reduced via employing domestic PVA fibers.It is,therefore,feasible to produce low cost ECC material employing domestic PVA fibers,while simultaneously retaining high material ductility.
基金The National Natural Science Foundation of China(No. 51008071)the Natural Science Foundation fo Jiangsu Province(No. BK2010413)Teaching & Research Excellence Grant for Young Faculty Members at Southeast University,the US National Science Foundation (No. CMS-0223971,CMS-0329416)
文摘In order to avoid brittle fracture failure, a ductile engineered cementitious composite （ECC） was attempted in steel/concrete connection zones to replace normal concrete. The influence of the ECC material ductility on connection failure modes and structural performance was investigated via the pushout test of stud/ECC connection, the pullout test of two-dimensional anchor bolt/ECC connection and the finite element modeling （FEM）. The experimental results suggest that the micromechanically designed ECC with a tensile ductility 300 times that of normal concrete switches the brittle fracture failure mode to a ductile one in steel connection zones. This modification in material behavior leads to higher load carrying capacity and structural ductility, which is also confirmed in FEM investigation. The enhancement in structural response through material ductility engineering is expected to be applicable to a wide range of engineering structures where steel and concrete come into contact.
基金This work was financially supported by the National Re-search Foundation of Korea(NRF)funded by the Ministry of Science,ICT(Nos.NRF-2019M3D1A2104108,2019R1A2C1084010,2020R1A4A2002161,and 2020R1A6A3A13073172)。
文摘Blue photodetectors(PDs)are attracting great attention for various applications.Commercial blue PDs based on inorganic GaP or InGaN absorbers are limited by their expensive,complex,and high-temperature fabrication techniques.Organic absorber-based blue PDs still have much lower photode-tecting properties than inorganic blue PDs.In this study,a high-performance self-powered blue PD is developed using methylammonium lead halide(MAPbX_(3);X=I,Br,and Cl)perovskites based on the eco-nomic and facile solution process at low temperatures.Optimal composition is obtained through halide-composition engineering.Our best-performing device exhibits an average external quantum efficiency and an average detectivity of 42.7%and 8.65×10^(11) Jones,respectively,within the blue region.The peak responsivity of the proposed PD is 0.174 A W^(−1) at 455 nm,which is comparable to that of commercial gallium phosphide blue PD(0.180 A W^(−1) at 470 nm).Moreover,the proposed device exhibits excellent environmental stability under ambient air conditions.These findings will act as a basis for next-generation image sensor technologies,such as vertically stacked red/green/blue PDs.
基金supported by the National Natural Science Foundation of China (52002412 and 22072186)the Natural Science Foundation of Guangdong Province (2021A1515010575)the Fundamental Research Funds for the Central Universities, Sun Yat-sen University (23lgbj017)。
文摘Exploiting high-efficiency Ni-based materials for electrocatalytic urea oxidation reaction(UOR) is critical for urea-related technologies.The catalytic site density,intrinsic activity,charge transfer,and mass diffusion determine overall electrocatalytic efficiency.Simultaneous modulation over the above four factors promises advanced electrocatalysis,yet challenging.Herein we propose a systematic regulation tactic over composition and geometric structure,constructing a nanocomposite comprising Mn doped Ni_(3)N nanoparticles anchored on reduced graphene oxide(rGO/Mn-Ni_(3)N),achieving elegant integration of four design principles into one,thereby eminently boosting UOR.Particularly,Mn doping in Ni_(3)N can modulate electronic state to induce intrinsic activity regulation.Combining metallic Mn-Ni_(3)N with rGO to engineer hierarchical architecture not only promotes charge transfer,but also enriches active site population.Intriguingly,improved hydrophilicity could impart better electrolyte penetration and gas escape.Consequently,such system-optimized rGO/Mn-Ni_(3)N demonstrates state-of-the-art-level UOR electrocatalysis.This work offers a novel paradigm to create advanced catalysts via systematic and integrated modulation.
基金supported by the National Natural Science Foundation of China (51702038)National Natural Science Foundation of China (51773045, 21772030, 51922032, 21961160720) for financial support+1 种基金the Recruitment Program for Young ProfessionalsNational Key Research and Development Program of China (2017YFA0206600)。
文摘Perovskite quantum-dots (PQDs) have emerged as prominent candidates for intriguing photovoltaic application due to their superior optoelectronic properties such as multiple exciton generation, bandgap tunability, electronic and surface chemistry properties, as well as flexible composition [1–5].
基金The National Natural Science Foundation of China(No. 50808043)the National Basic Research Program of China (973 Program) (No. 2009CB623200)Foundation of Jiangsu Key Laboratory of Construction Materials,Program for Special Talents in Six Fields of Jiangsu Province(No. 2011-JZ-010)
文摘An engineered cementitious composite （ECC） is introduced to partially substitute concrete in the tension zone of a reinforced concrete beam to form an ECC/reinforced concrete （RC） composite beam, which can increase the ductility and crack resisting ability of the beam. Based on the assumption of the plane remaining plane and the simplified constitutive models of materials, the stress and strain distributions along the depth of the composite beam in different loading stages are comprehensively investigated to obtain calculation methods of the load-carrying capacities for different stages. Also, a simplified formula for the ultimate load carrying capacity is proposed according to the Chinese code for the design of concrete structures. The relationship between the moment and curvature for the composite beam is also proposed together with a simplified calculation method for ductility of the ECC/RC composite beam. Finally, the calculation method is demonstrated with the test results of a composite beam. Comparison results show that the calculation results have good consistency with the test results, proving that the proposed calculation methods are reliable with a certain theoretical significance and reference value.
基金The National Natural Science Foundation of China(No.51278118)Program for Special Talents in Six Fields of Jiangsu Province(No.2011JZ010)+1 种基金the Natural Science Foundation of Jiangsu(No.BK2012756)the National Undergraduate Innovative Experiment Program(No.111028660)
文摘In order to investigate the flexural behaviors of engineered cementitious composites （ECC）, theoretical and experimental researches are done on flexural doublereinforced ECC beams. Based on the assumption of the plane section remaining plane in bending and simplified constitutive models of materials, the calculation methods of load carrying capacities for different critical stages are obtained. Then, these calculation methods are demonstrated by comparing the test results with the calculation results. Finally, based on the proposed theoretical formulae, the effects of the compression strength, compression strain and tension strength of ECC, and the reinforcement ratio on the flexural behaviors of double-reinforced ECC beams are analyzed. The calculated and measured results are in good agreement, which indicates that the theoretical model can be used to predict the momentcurvature response of steel reinforced ECC beams. And the results of parametric studies show that the increase in the compression strength of ECC can greatly improve the flexural performance of beams; the increase in the ultimate compression strain can significantly improve the ultimate curvature and ductility, but has little effect on the load bearing capacity of beams. little effect on the flexural The tensile strength of ECC has behaviors of ECC beams. The increase in the steel reinforcement ratio can lead to significant improvement of the load bearing capacity and the stiffness of beams, but a degradation of the ductility of beams. The theoretical model and parameter analysis results in this paper are instructive for the design of steel reinforced ECC beams.
