Mechanical metamaterials can be defined as a class of architected materials that exhibit unprecedented mechanical properties derived from designed artificial architectures rather than their constituent *** macroscale ...
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Mechanical metamaterials can be defined as a class of architected materials that exhibit unprecedented mechanical properties derived from designed artificial architectures rather than their constituent *** macroscale and simple layouts can be realized by conventional top-down manufacturing approaches,many of the sophisticated designs at various length scales remain elusive,due to the lack of adequate manufacturing *** progress in additive manufacturing(AM)has led to the realization of a myriad of novel metamaterial *** methods capable of fabricating microscale architectures with high resolution,arbitrary complexity,and high feature fidelity have enabled the rapid development of architected meta materials and drastically reduced the design-computation and experimental-validation *** paper first provides a detailed review of various topologies based on the desired mechanical properties,including stiff,strong,and auxetic(negative Poisson’s ratio)metamaterials,followed by a discussion of the AM technologies capable of fabricating these ***,we discuss current challenges and recommend future directions for AM and mechanical metamaterials.
To satisfy the requirements of substantial green development,it is urgent to explore an innovative eco‐friendly semiconductor photocatalyst to efficiently achieve visible‐light‐driven photocatalytic H 2 evolution(P...
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To satisfy the requirements of substantial green development,it is urgent to explore an innovative eco‐friendly semiconductor photocatalyst to efficiently achieve visible‐light‐driven photocatalytic H 2 evolution(PHE).The strategy of promoting the spatial separation efficiency of photoinduced carriers can essentially enhance the PHE performance of a ***,a graphitic carbon nitride(g‐C 3 N 4)‐based donor–acceptor(D‐A)copolymer(CNDM x)is constructed by simple one‐pot thermal polycondensation,using urea and 5,8‐DibroMoquinoxaline(as an electron donor)as *** electron D-A modulation consequently creates an internal electric field to facilitate the intramolecular charge transfer within the copolymer.A series of experimental characterizations and density functional theory calculations are applied to elucidate the variation and correlation of the structure and PHE performance of the as-prepared *** is found that the best average PHE rate of 3012.5μmolg^(−1) h^(−1) can be achieved over the optimal D-A copolymer under visible‐light(400<λ<800nm)irradiation,which is~3.3 times that of pure urea-derived g-C_(3)N_(4).The corresponding apparent quantum efficiency is 1.3% at *** study provides a protocol for designing effective visible-light photocatalysts via D-A modulation of polymeric semiconductors.
In this work,wemodeled the brittle fracture of shell structure in the framework of Peridynamics Mindlin-Reissener shell theory,in which the shell is described by material points in themean-plane with its drilling rota...
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In this work,wemodeled the brittle fracture of shell structure in the framework of Peridynamics Mindlin-Reissener shell theory,in which the shell is described by material points in themean-plane with its drilling rotation neglected in kinematic *** improve the numerical accuracy,the stress-point method is utilized to eliminate the numerical instability induced by the zero-energy mode and *** crack surface is represented explicitly by stress points,and a novel general crack criterion is proposed based on *** of the critical stretch used in common peridynamic solid,it is convenient to describe thematerial failure by using the classic constitutive model in continuum *** this work,a concise crack simulation algorithm is also provided to describe the crack path and its development,in order to simulate the brittle fracture of the shell *** examples are presented to validate and demonstrate our proposed *** reveal that our model has good accuracy and capability to represent crack propagation and branch spontaneously.
MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface ***,electrodes based on MXene m...
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MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface ***,electrodes based on MXene may result in low ion-accessible surface area and blocked ion transport pathways because of the self-restacking of MXene *** is essential to suppress the self-res tacking of nanosheets and increase the electrochemical active sites in order to optimize the *** this work,bidirectionally aligned MXene hybrid aerogel(A-MHA)assembled with MXene nanosheets and microgels is prepared using a facile bidirectional freeze casting and freeze-drying *** bidirectionally aligned structure together with the three-dimensional structured microgels in the A-MHAs,can improve the ionaccessible surface area and provide more barrier-free channels by exposing more active sites and ensuring electrolyte transport *** A-MHA with MXene microgels content of 40 wt%exhibits a high specific capacitance of 760 F·g^(-1)at 1 A·g^(-1)and a remarkable cyclic performance of 97%after 10,000 cycles at100 mV·s^(-1)in 1 mol·L^(-1)H_(2)SO_(4)electrolyte.A-MHAs show remarkable electrochemical properties and are of potential application in energy storage.
Hollow nitrogen-doped porous carbon materials covered with different thicknesses of carbon layers were synthesized to assist evaluation of the influence of nitrogen atom on the surrounding carbon *** designed carbon-b...
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Hollow nitrogen-doped porous carbon materials covered with different thicknesses of carbon layers were synthesized to assist evaluation of the influence of nitrogen atom on the surrounding carbon *** designed carbon-based materials were synthesized through pyrolysis of surface-attached block copolymer layers on silica nanoparticles with different thicknesses of the second block of grafted polymer chains,followed by removal of silica *** experimental results reveal that coverage a carbon layer with proper thickness can improve the oxygen reaction reduction activity of nitrogen-doped carbon materials as evidenced by the positive shift of half-wave potential in linear scanning voltammetry response *** conclusions may provide a reference work on understanding the active sites and designing materials with superior electrochemical performance.
Porous carbon spheres represent an ideal family of electrode materials forsupercapacitors because of the high surface area,ideal conductivity,negligible aggregation,and ability to achieve space efficient ***,the devel...
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Porous carbon spheres represent an ideal family of electrode materials forsupercapacitors because of the high surface area,ideal conductivity,negligible aggregation,and ability to achieve space efficient ***,the development of new synthetic methods towards porous carbon spheres still remains a great ***,N-doped hollow carbon spheres with an ultrahigh surface area of2044 m^(2)/g have been designed based on the phenylenediamine-formaldehyde *** applied in symmetric supercapacitors with ionic electrolyte(EMIBF_4),the obtained N-doped hollow carbon spheres demonstrate a high capacitance of 234 F/g,affording an ultrahigh energy density of 114.8 Wh/*** cycling stability has also been *** impressive capacitive performances make the phenylenediamine-formaldehyde resin derived N-doped carbon a promising candidate electrode material for supercapacitors.
A recombinant protein ChiSifiCa,which was originally designed for regulation of calcium carbonate,was utilized to direct the mineralization of PbI_(2).By the regulation of ChiSifiCa protein,PbI_(2)nanoparticles compos...
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A recombinant protein ChiSifiCa,which was originally designed for regulation of calcium carbonate,was utilized to direct the mineralization of PbI_(2).By the regulation of ChiSifiCa protein,PbI_(2)nanoparticles composed of crystalline nanoflakes and amorphous nanorods were fabricated under environmental benign *** PbI_(2)was successfully applied for preparation of perovskite precursors to fabricate solar *** regulation of ChiSifiCa on PbI_(2)improves the power conversion efficiency of corresponding perovskite solar cells to 16%.The present study may open a new avenue in the design and synthesis of materials with novel structures and functions.
The densification and the structure evolution of the plasma activated sintered(PAS sintered)ZrB_(2)-ZrO_(2) composite via the ZrO_(2)-coated ZrB_(2) powder(ZrB_(2)@ZrO_(2))prepared by in situ passivation method were *...
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The densification and the structure evolution of the plasma activated sintered(PAS sintered)ZrB_(2)-ZrO_(2) composite via the ZrO_(2)-coated ZrB_(2) powder(ZrB_(2)@ZrO_(2))prepared by in situ passivation method were *** composition and microstructure were characterized by XRD,Raman,SEM,and EDS *** coated powder has excellent sintering *** relative density of the composite reaches above 90%at 1200℃,and the main sintering process occurs between ZrO_(2) *** at above 1500℃,the relative density reaches above 95%and the main sintering process occurs between ZrB_(2) and ZrO_(2) *** the increase of ZrO_(2) coating content,the structure of the sintered body changes from ZrB_(2) continuous network structure to island *** the content is 20%,an island structure is *** the ZrO_(2) content further causes the overheating of ZrO_(2).Thus,the best sintering performance reaches when the coating content is 20wt%.
Titanium diboride ceramic was produced via spark plasma sintering(SPS)using finer TiB_(2)powder made by high-speed planetary ball *** effects of ball milling parameters on the composites and particle size of TiB_(2)po...
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Titanium diboride ceramic was produced via spark plasma sintering(SPS)using finer TiB_(2)powder made by high-speed planetary ball *** effects of ball milling parameters on the composites and particle size of TiB_(2)powder were *** was shown that the average particle size of TiB_(2)powder decreased from 5.8 to 1.59μm and the wear rate of WC balls was 1.58 wt%,when the ball-to-powder weight ratio(BPR),the rotary speed and milling time and were 10:1,600 rpm and 20 min,*** content of WC in TiB_(2)powder can be limited below 4.58 vol%by optimizing the milling *** sintering temperature of TiB_(2)powder milled can be decreased obviously,and the mechanical properties are evidently improved and the microstructure becomes more homogeneous when the powder of TiB_(2)becomes *** relative density,hardness,bending strength,and fracture toughness of the TiB_(2)ceramic fabricated at 1700℃reach the optimal values,which are 98.13%,19.14 GPa,756 MPa,and 5.71 MPa·m~(1/2),*** decrease of TiB_(2)particle size and the introduction of WC are the potential reasons for the improvement of TiB_(2)ceramic performance.
Local phase transition in transition metal dichalcogenides (TMDCs) by lithiumintercalation enables the fabrication of high-quality contact interfaces in twodimensional(2D) electronic devices. However, controlling the ...
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Local phase transition in transition metal dichalcogenides (TMDCs) by lithiumintercalation enables the fabrication of high-quality contact interfaces in twodimensional(2D) electronic devices. However, controlling the intercalation oflithium is hitherto challenging in vertically stacked van der Waalsheterostructures (vdWHs) due to the random diffusion of lithium ions in thehetero-interface, which hinders their application for contact engineering of 2DvdWHs devices. Herein, a strategy to restrict the lithium intercalation pathwayin vdWHs is developed by using surface-permeation assisted intercalationwhile sealing all edges, based on which a high-performance edge-contact MoS_(2)vdWHs floating-gate transistor is demonstrated. Our method avoids intercalationfrom edges that are prone to be random but intentionally promotes lithiumintercalation from the top surface. The derived MoS_(2) floating-gatetransistor exhibits improved interface quality and significantly reduced subthresholdswing (SS) from >600 to 100 mV dec^(–1). In addition, ultrafast program/erase performance together with well-distinguished 32 memory statesare demonstrated, making it a promising candidate for low-power artificialsynapses. The study on controlling the lithium intercalation pathways in 2DvdWHs offers a viable route toward high-performance 2D electronics for memoryand neuromorphic computing purposes.
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