Most of the challenges experienced by many engineering materials originate from the surface which later leads to total failure,hence affecting the resultant mechanical properties and service life.However,these challen...Most of the challenges experienced by many engineering materials originate from the surface which later leads to total failure,hence affecting the resultant mechanical properties and service life.However,these challenges have been addressed thanks to the invention of a novel surface mechanical attrition treatment(SMAT)method which protects the material surface by generating a gradient-structured layer with improved strength and hardness without jeopardizing the ductility.The present work provides a comprehensive literature review on the mechanical properties of materials after SMAT including the hardness,tensile strength and elongation,and residual stress.Firstly,a brief introduction on the different forms of surface nanocrystallization is given to get a better understanding of the SMAT process and its advantages over other forms of surface treatments,and then the grain refinement mechanisms of materials by SMAT from the matrix region(base material)to the nanocrystallized layer are explained.The effects of fatigue,fracture,and wear of materials by the enhanced mechanical properties after SMAT are also discussed in detail.In addition,the various applications of SMAT ranging from automotive,photoelectric conversion,biomedical,diffusion,and 3 D-printing of materials are extensively discussed.The prospects and recent research trends in terms of mechanical properties of materials affected by SMAT are then summarized.展开更多
Over the past 30 years,additive manufacturing(AM)has developed rapidly and has demonstrated great potential in biomedical applications.AM is a materials-oriented manufacturing technology,since the solidification mecha...Over the past 30 years,additive manufacturing(AM)has developed rapidly and has demonstrated great potential in biomedical applications.AM is a materials-oriented manufacturing technology,since the solidification mechanism,architecture resolution,post-treatment process,and functional application are based on the materials to be printed.However,3D printable materials are still quite limited for the fabrication of bioimplants.In this work.2D/3D AM materials for bioimplants are reviewed.Furthermore,inspired by Tai Chi,a simple yet novel soft/rigid hybrid 4D AM concept is advanced to develop complex and dynamic biological structures in the human body based on 4D printing hybrid ceramic precursor/ceramic materials that were previously developed by our group.With the development of multi-material printing technology,the development of bioimplants and soft/rigid hybrid biological structures with 2D/3D/4D AM materials can be anticipated.展开更多
Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,lim...Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,limiting their practical applications.Herein,we propose a hierarchical salt-rejection(HSR)strategy to prevent salt precipitation during long-term evaporation while maintaining a rapid evaporation rate,even in high-salinity brine.The salt diffusion process is segmented into three steps—insulation,branching diffusion,and arterial transport—that significantly enhance the salt-resistance properties of the evaporator.Moreover,the HSR strategy overcomes the tradeoff between salt resistance and evaporation rate.Consequently,a high evaporation rate of 2.84 kg m^(-2) h^(-1),stable evaporation for 7 days cyclic tests in 20 wt%NaCl solution,and continuous operation for 170 h in natural seawater under 1 sun illumination were achieved.Compared with control evaporators,the HSR evaporator exhibited a>54%enhancement in total water evaporation mass during 24 h continuous evaporation in 20 wt%salt water.Furthermore,a water collection device equipped with the HSR evaporator realized a high water purification rate(1.1 kg m^(-2) h^(-1)),highlighting its potential for agricultural applications.展开更多
Dual-phase metallic glasses(DP-MGs),a special member of the MGs family,often reveal unusual strength and ductility,yet,their corrosion behaviors are not understood.Here,we developed a nanostructured Mg_(57)Zn_(36)Ca_(...Dual-phase metallic glasses(DP-MGs),a special member of the MGs family,often reveal unusual strength and ductility,yet,their corrosion behaviors are not understood.Here,we developed a nanostructured Mg_(57)Zn_(36)Ca_(7)(at.%)DP-MG and uncovered its corrosion mechanism in simulated body fluid(SBF)at the near-atomic scale utilizing transmission electron microscope(TEM)and atom probe tomography(APT).The 10-nm-wide Ca-rich amorphous phases allow oxygen propagation into the DP-MG,resulting in a micrometer thick hydroxides/oxides layer.This dense corrosion layer protects the DP-MG from further corrosion,enabling a corrosion rate that is 77%lower than that of Mg(99.99%purity).展开更多
1.Research and development(R&D)and the challenges of raw materials for medical additive manufacturing Raw materials for medical additive manufacturing have a wide range of commonalities that are also seen in many ...1.Research and development(R&D)and the challenges of raw materials for medical additive manufacturing Raw materials for medical additive manufacturing have a wide range of commonalities that are also seen in many other fields,making them an important basis in the field of three-dimensional(3D)printing.Problems and challenges related to material types,powder properties,formability,viscoelasticity,and so forth also share common features.For example,many metal materials are used in the field of aviation,while metals,polymers,and inorganic materials are used in the field of biomedicine.The most widely used materials in biomedicine are biocompatible.Various homogeneous and non-homogeneous composites are also available for 3D printing,and impose an additional challenge in additive manufacturing;the use of heterogeneous composites in 3D printing is particularly challenging.展开更多
In the past decades,metal-containing nanomaterials have attracted increasing interests owing to their intriguing physicochemical properties and various promising applications.Recent research has revealed that the phas...In the past decades,metal-containing nanomaterials have attracted increasing interests owing to their intriguing physicochemical properties and various promising applications.Recent research has revealed that the phase of metal-containing nanomaterials could significantly affect their properties and functions.In particular,nanomaterials with amorphous phase,which possess long-range disordered atomic arrangements,and the amorphous/crystalline heterophase nanostructures comprised of both amorphous and crystalline phases,have exhibited superior performance in various applications,e.g.,catalysis and energy storage.In this review,a brief overview of the recent progress on the wet-chemical synthesis and applications of amorphous and amorphous/crystalline heterophase metal-containing nanomaterials has been provided.Subsequently,on the basis of different categories of metal-containing nanomaterials,including metals,metal alloys,and metal compounds,their synthetic routes and promising applications will be highlighted.Finally,current challenges and some personal perspectives in this emerging research field will be proposed.展开更多
Improving the catalytic activity of non-noble metal single atom catalysts(SACs)has attracted considerable attention in materials science.Although optimizing the local electronic structure of single atom can greatly im...Improving the catalytic activity of non-noble metal single atom catalysts(SACs)has attracted considerable attention in materials science.Although optimizing the local electronic structure of single atom can greatly improve their catalytic activity,it often involves in-plane modulation and requires high temperatures.Herein,we report a novel strategy to manipulate the local electronic structure of SACs via the modulation of axial Co-S bond anchored onto graphitic carbon nitride(C_(3)N_(4))at room temperature(RT).Each Co atom is bonded to four N atoms and one S atom(Co-(N,S)/C_(3)N_(4)).Owing to the greater electronegativity of S in the Co-S bond,the local electronic structure of the Co atoms is available to be controlled at a relatively moderate level.Consequently,when employed for the photocatalytic hydrogen evolution reaction,the adsorption energy of intermediate hydrogen(H*)on the Co atoms is remarkably low.In the presence of the Co-(N,S)/C_(3)N_(4)SACs,the hydrogen evolution rates reach up to 10 mmol/(g·h),which is nearly 10 and 2.5 times greater than the rates in the presence of previously reported transition metal/C_(3)N_(4)and noble platinum nanoparticles(PtNPs)/C_(3)N_(4)catalysts,respectively.Attributed to the tailorable axial Co-S bond in the SAC,the local electronic structure of the Co atoms can be further optimized for other photocatalytic reactions.This axial coordination engineering strategy is universal in catalyst designing and can be used for a variety of photocatalytic applications.展开更多
As a revolutionary industrial technology,additive manufacturing creates objects by adding materials layer by layer and hence can fabricate customized components with an unprecedented degree of freedom.For metallic mat...As a revolutionary industrial technology,additive manufacturing creates objects by adding materials layer by layer and hence can fabricate customized components with an unprecedented degree of freedom.For metallic materials,unique hierarchical microstructures are constructed during additive manufacturing,which endow them with numerous excellent properties.To take full advantage of additive manufacturing,an in-depth understanding of the microstructure evolution mechanism is required.To this end,this review explores the fundamental procedures of additive manufacturing,that is,the formation and binding of melt pools.A comprehensive processing map is proposed that integrates melt pool energy-and geometry-related process parameters together.Based on it,additively manufactured microstructures are developed during and after the solidification of constituent melt pool.The solidification structures are composed of primary columnar grains and fine secondary phases that form along the grain boundaries.The post-solidification structures include submicron scale dislocation cells stemming from internal residual stress and nanoscale precipitates induced by intrinsic heat treatment during cyclic heating of adjacent melt pool.Based on solidification and dislocation theories,the formation mechanisms of the multistage microstructures are thoroughly analyzed,and accordingly,multistage control methods are proposed.In addition,the underlying atomic scale structural features are briefly discussed.Furthermore,microstructure design for additive manufacturing through adjustment of process parameters and alloy composition is addressed to fulfill the great potential of the technique.This review not only builds a solid microstructural framework for metallic materials produced by additive manufacturing but also provides a promising guideline to adjust their mechanical properties.展开更多
The recent studies on nanotwinned(NT)and hierarchical nanotwinned(HNT)face-centered cubic(FCC)metals are presented in this review.The HNT structures have been supposed as a kind of novel structure to bring about highe...The recent studies on nanotwinned(NT)and hierarchical nanotwinned(HNT)face-centered cubic(FCC)metals are presented in this review.The HNT structures have been supposed as a kind of novel structure to bring about higher strength/ductility than NT counterparts in crystalline materials.We primarily focus on the recent developments of the experimental,atomistic and theoretical studies on the NT and HNT structures in the metallic materials.Some advanced bottom-up and top-down techniques for the fabrication of NT and HNT structures are introduced.The deformation induced HNT structures are available by virtue of severe plastic deformation(SPD)based techniques while the synthesis of growth HNT structures is so far almost unavailable.In addition,some representative molecular dynamics(MD)studies on the NT and HNT FCC metals unveil that the nanoscale effects such as twin spacing,grain size and plastic anisotropy greatly alter the performance of NT and HNT metals.The HNT structures may initiate unique phenomena in comparison with the NT ones.Furthermore,based on the phenomena and mechanisms revealed by experimental and MD simulation observations,a series of theoretical models have been proposed.They are effective to describe the mechanical behaviors of NT and HNT metals within the applicable scope.So far the development of manufacturing technologies of HNT structures,as well as the studies on the effects of HNT structures on the properties of metals are still in its infancy.Further exploration is required to promote the design of advanced materials.展开更多
Amorphous nanomaterials with long-range disordered structures could possess distinct properties and promising applications,especially in catalysis,as compared with their conventional crystalline counterparts.It is imp...Amorphous nanomaterials with long-range disordered structures could possess distinct properties and promising applications,especially in catalysis,as compared with their conventional crystalline counterparts.It is imperative to achieve the controlled preparation of amorphous noble metal-based nanomaterials for the exploration of their phase-dependent applications.Here,we report a facile wet-chemical reduction strategy to synthesize various amorphous multimetallic Pd-based nanomaterials,including PdRu,PdRh,and PdRuRh.The phase-dependent catalytic performances of distinct Pd-based nanomaterials towards diverse catalytic applications have been demonstrated.Specifically,the usage of PdRu nanocatalysts with amorphous and crystalline face-centered cubic(fcc)phases can efficiently switch the ring-opening route of styrene oxide to obtain different products with high selectivity through alcoholysis reaction and hydrogenation reaction,respectively.Moreover,when used as an electrocatalyst for hydrogen evolution reaction(HER),the synthesized amorphous PdRh nanocatalyst exhibits low overpotential and high turnover frequency values,outperforming its crystalline fcc counterpart and most of the reported Pd-based HER electrocatalysts.展开更多
As an important parameter of crystalline materials,the crystal phase describes the periodic atomic arrangement in their structures.For some monoelemental materials,e.g.,carbon and phosphorus,they can exist in more tha...As an important parameter of crystalline materials,the crystal phase describes the periodic atomic arrangement in their structures.For some monoelemental materials,e.g.,carbon and phosphorus,they can exist in more than one crystal phase.The different crystal phases of monoelemental materials result in different physicochemical properties and functions.Therefore,engineering the crystal phase of monoelemental materials gives an effective strategy to modulate their properties and functions.Conventionally,the crystal phase of monoelemental materials can be altered under some harsh conditions,e.g.,high temperature and high pressure.Recently,with the rapid development of nanotechnology,various monoelemental materials with unconventional crystal phases have been well developed on the nanoscale.For example,our group has successfully achieved the synthesis of Au nanomaterials with unconventional hexagonal close-packed(hcp)2H and 4H phases by wetchemical methods,which exhibit distinct optical properties as well as outstanding electrocatalytic performance when compared to those with a thermodynamically stable facecentered cubic(fcc)phase.In this Account,we give a comprehensive overview of the recent development of monoelemental nanomaterials with unconventional crystal phases and their crystal-phase-dependent properties and applications.We first introduce the typical strategies for the synthesis of monoelemental nanomaterials with unconventional crystal phases.By using a wet-chemical reduction method,template-assisted method,and thermal annealing method,monoelemental nanomaterials with unconventional crystal phases can be directly prepared.Besides,unconventional-phase monoelemental nanomaterials can also be obtained via the phase transformation from materials with conventional crystal phases under specific conditions.In addition,some other methods have also been reported for preparing monoelemental nanomaterials with unconventional crystal phases,such as controlled crystallization of amorphous structure,the chemical vapor transport(CVT)method,electrodeposition,galvanic replacement,sputter-deposition,and so on.Subsequently,we summarize the unique structural stability and magnetic,electronic,optical,and other properties of the obtained monoelemental nanomaterials with unconventional crystal phases.We also highlight their promising applications in catalysis and batteries.Finally,we present our personal perspectives on the challenges and future opportunities in this important research field.展开更多
Hall-Petch relation was widely applied to evaluate the grain size effect on mechanical properties of metallic material. However, the sample size effect on the Hall-Petch relation was always ignored. In the present stu...Hall-Petch relation was widely applied to evaluate the grain size effect on mechanical properties of metallic material. However, the sample size effect on the Hall-Petch relation was always ignored. In the present study, the mechanical test and microstructure observation were performed to investigate the combined effects of grain and sample sizes on the deformation behaviors of gold microwires. The polycrystalline gold microwires with diameter of 16 ?m were annealed at temperatures from 100°C to 600°C, leading to different ratios(t/d) of wire diameter(t) to grain size(d) from 0.9 to 16.7. When the t/d was lower than 10, the yield stress dropped fast and deviated from the Hall-Petch relation. The free-surface grains played key role in the yield stress softening, and the volume fraction of free-surface grains increased with the t/d decreasing. Furthermore, the effects of t/d on work-hardening behaviors and fracture modes were also studied. With t/d value decreasing from 17 to 3.4, the samples exhibited necking fracture and the dislocation pile-ups induced work-hardening stage was gradually activated.With the t/d value further decreasing(t/d < 3.4), the fracture mode turned into shear failure, and the work-hardening capability lost. As the gold microwire for wire bonding is commonly applied in the packaging of integrated circuit chips, and the fabrication of microwire suffers multi-pass cold-drawing and annealing treatments to control the grain size. The present study could provide instructive suggestion for gold microwire fabrication and bonding processes.展开更多
Crystal phase can greatly affect the physicochemical properties and applications of nanomaterials.However,it stil remains a great challenge to synthesize nanostructures with the same composition and morphology but dif...Crystal phase can greatly affect the physicochemical properties and applications of nanomaterials.However,it stil remains a great challenge to synthesize nanostructures with the same composition and morphology but different phases in order to explore the phase-dependent properties and applications.Herein,we report the crystal phase-controlled synthesis of PtCu alloy shells on 4H Au nanoribbons(NRBs),referred to as 4H-Au NRBs,to form the 4H-Au@PtCu core-shell NRBs.By tuning the thickness of PtCu,4H-PtCu and face-centered cubic(cc)phase PICu(cc-PtCu)alloy shells are successtully grown on the 4H-Au NRB cores.This thickness-dependent phase-controlled growth strategy can also be used to grow PtCo alloys with 4H or fcc phase on 4H-Au NRBs.Significantly,when used as electrocatalysts for the ethanol oxidation reaction(EOR)in alkaline media,the 4H-Au@4H-PtCu NRBs show much better EOR performance than the 4H-Au@fcc-PtCu NRBs,and both of them possess superior performance compared to the commercial Pt black.Our study provides a strategy on phase-contolled synthesis of nanomaterials used for crystal phase-dependent applications.展开更多
Mineral hydrogels have caught a lot of attention for their strong competency as artificial skin-like materials.Nonetheless,it remains a great difficulty in fulfilling in one hydrogel system a range of key functionalit...Mineral hydrogels have caught a lot of attention for their strong competency as artificial skin-like materials.Nonetheless,it remains a great difficulty in fulfilling in one hydrogel system a range of key functionalities that are needed for practical artificial skin applications,i.e.,to be biocompatible,strain-sensitive,ion-conductive,elastic and robust,anti-swelling,and anti-freezing.Here we present a such type of versatile hydrogel that is not only capable to deliver all the above-mentioned key functionalities but also highly stable.This novel hydrogel is constructed by introducing a gelatinous and amorphous multi-ionic biomineral(denoted as Mg-ACCP,containing Mg^(2+),Ca^(2+),CO_(3)^(2−),and PO_(4)^(3−))into the network of biocompatible polyvinyl alcohol(PVA)and sodium alginate(SA).The presence of Mg^(2+)and PO_(4)^(3−)in this hydrogel helps prohibit the crystallization of the biominerals,leading to significantly improved stability.The hydrogel thus obtained delivers excellent mechanical performance due to the chelation between the mineral ions and the organic matrix,and high sensitivity even to subtle pressure and strain applied,such as slight finger bending and gentle tapping.Furthermore,the novel hydrogel features high ionic conductivity,high resistance to swelling,and extraordinary anti-freezing property,holding great promise for applications in different practical scenarios,particularly in aqueous or cold environments.展开更多
Cost-effective, rapid, and accurate virus detection technologies play key roles in reducing viral transmission. Prompt and accurate virus detection enables timely treatment and effective quarantine of virus carrier, a...Cost-effective, rapid, and accurate virus detection technologies play key roles in reducing viral transmission. Prompt and accurate virus detection enables timely treatment and effective quarantine of virus carrier, and therefore effectively reduces the possibility of large-scale spread. However, conventional virus detection techniques often suffer from slow response, high cost or sophisticated procedures. Recently, two-dimensional(2D) materials have been used as promising sensing platforms for the highperformance detection of a variety of chemical and biological substances. The unique properties of 2D materials, such as large specific area, active surface interaction with biomolecules and facile surface functionalization, provide advantages in developing novel virus detection technologies with fast response and high sensitivity. Furthermore, 2D materials possess versatile and tunable electronic, electrochemical and optical properties, making them ideal platforms to demonstrate conceptual sensing techniques and explore complex sensing mechanisms in next-generation biosensors. In this review, we first briefly summarize the virus detection techniques with an emphasis on the current efforts in fighting again COVID-19. Then, we introduce the preparation methods and properties of 2D materials utilized in biosensors, including graphene, transition metal dichalcogenides(TMDs) and other 2D materials. Furthermore, we discuss the working principles of various virus detection technologies based on emerging 2D materials, such as field-effect transistor-based virus detection, electrochemical virus detection, optical virus detection and other virus detection techniques. Then, we elaborate on the essential works in 2D material-based high-performance virus detection. Finally, our perspective on the challenges and future research direction in this field is discussed.展开更多
Fabrication of single-crystalline metal-organic framework(MOF)hollow nanostructures with two-dimensional(2D)morphologies is a challenging task.Herein,twin-like MOF nanobricks,a quasi-hollow 2D architecture,with multi-...Fabrication of single-crystalline metal-organic framework(MOF)hollow nanostructures with two-dimensional(2D)morphologies is a challenging task.Herein,twin-like MOF nanobricks,a quasi-hollow 2D architecture,with multi-metal nodes and replaceable organic ligands,are uniformly and firmly grown on conductive Ni foam through a generic one-pot approach.The formation process of twin-like MOF nanobricks mainly includes selective epitaxial growth of Fe-rich MOF layer and simultaneously dissolution of the pre-formed Ni-rich metal-organic frameworks(MOFs),all of which can be ascribed to a special self-templated mechanism.The fantastic structural merits of twin-like MOF nanobrick arrays,featuring highly exposed active sites,remarkable electrical conductivity,and hierarchical porosities,enable this material for efficient electrocatalysis.Using bimetallic NiFe-MOFs grown on Ni foam as an example,the resultant twin-like nanobrick arrays can be directly utilized as three-dimensional(3D)integrated electrode for high-performance water oxidation in 1 M KOH with a low overpotential,fast reaction kinetics(28.5 mV·dec^(-1)),and superb stability.Interestingly,the unstable NiFe-MOFs were served as an oxygen evolution reaction(OER)pre-catalyst and the single-crystalline NiFe-MOF precursor can be in-situ topochemically regulated into porous and lowcrystalline NiFeOx nanosheets during the OER process.This work extends the hollowing strategy to fabricate hollow MOFs with 2D architectures and highlights their direct utilization for advanced electrocatalysis.展开更多
The electrochemical CO_(2) reduction reaction(CO_(2)RR)offers a green and sustainable process to convert CO_(2) into valuable chemical stocks and fuels.Metal is one of the most promising types of catalysts to drive an...The electrochemical CO_(2) reduction reaction(CO_(2)RR)offers a green and sustainable process to convert CO_(2) into valuable chemical stocks and fuels.Metal is one of the most promising types of catalysts to drive an efficient and selective CO_(2)RR.The catalytic performance of metal nanocatalysts is strongly dependent on their structural features.Recently,phase engineering of nanomaterials(PEN)has emerged as a prominent tactic to regulate the catalytic performance of metal nanocatalysts for the CO_(2)RR.A broad range of metal nanocatalysts with conventional and unconventional crystal phases has been developed,and remarkable achievements have been made.This review summarizes the most recent developments in phase engineering of metal nanocatalysts for the electrochemical CO_(2)RR.We first introduce the different crystal phases of metal nanocatalysts used in the CO_(2)RR and then discuss various synthetic strategies for unconventional phases of metal nanocatalysts.After that,detailed discussions of metal nanocatalysts with conventional and unconventional phases,including amorphous phases,are presented.Finally,the challenges and perspectives in this emerging area are discussed.展开更多
Layered van der Waals(vdW)materials,consisting of atomically thin layers,are of paramount importance in physics,chemistry,and materials science owing to their unique properties and various promising applications.Howev...Layered van der Waals(vdW)materials,consisting of atomically thin layers,are of paramount importance in physics,chemistry,and materials science owing to their unique properties and various promising applications.However,their fast and large‐scale growth via a general approach is still a big challenge,severely limiting their practical implementations.Here,we report a universal method for rapid(~60 min)and large‐scale(gram scale)growth of phase‐pure,high‐crystalline layered vdW materials from their elementary powders via microwave plasma heating in sealed ampoules.This method can be used for growth of 30 compounds with different components(binary,ternary,and quaternary)and properties.The ferroelectric and transport properties of mechanically exfoliated flakes validate the high crystal quality of the grown materials.Our study provides a general strategy for the fast and large‐scale growth of layered vdW materials with appealing physiochemical properties,which could be used for various promising applications.展开更多
Comprehensive understanding of the structural/morphology stability of ultrathin (diameter 〈 10 nm) gold nanowires under real service conditions (such as under Joule heating) is a prerequisite for the reliable imp...Comprehensive understanding of the structural/morphology stability of ultrathin (diameter 〈 10 nm) gold nanowires under real service conditions (such as under Joule heating) is a prerequisite for the reliable implementation of these emerging building blocks into functional nanoelectronics and mechatronics systems. Here, by using the in situ transmission electron microscopy (TEM) technique, we discovered that the Rayleigh instability phenomenon exists in ultrathin gold nanowires upon moderate heating. Through the controlled electron beam irradiation-induced heating mechanism (with 〈 100 ~C temperature rise), we further quantified the effect of electron beam intensity and its dependence on Rayleigh instability in altering the geometry and morphology of the ultrathin gold nanowires. Moreover, in situ high-resolution TEM (HRTEM) observations revealed surface atomic diffusion process to be the dominating mechanism for the morphology evolution processes. Our results, with unprecedented details on the atomic-scale picture of Rayleigh instability and its underlying physics, provide critical insights on the thermal/structural stability of gold nanostructures down to a sub-10 nm level which may pave the way for their interconnect applications in future ultra- large-scale integrated ciroaits.展开更多
Integrating functional materials to form heterostructures with novel,sophisticated architectures has attracted extensive interest in chemistry and materials science^([1]).Heterostructures are expected to exhibit super...Integrating functional materials to form heterostructures with novel,sophisticated architectures has attracted extensive interest in chemistry and materials science^([1]).Heterostructures are expected to exhibit superior electrical,thermal,optical and magnetic properties due to the synergistic effect of their different components.Therefore,the rational design and preparation of heterostructures with controlled compositions,dimensions.展开更多
基金supports of the National Key R&D Program of China(Project No.2017YFA0204403)Hong Kong Themebased Research Scheme Ref.(T13-402/17-N).
文摘Most of the challenges experienced by many engineering materials originate from the surface which later leads to total failure,hence affecting the resultant mechanical properties and service life.However,these challenges have been addressed thanks to the invention of a novel surface mechanical attrition treatment(SMAT)method which protects the material surface by generating a gradient-structured layer with improved strength and hardness without jeopardizing the ductility.The present work provides a comprehensive literature review on the mechanical properties of materials after SMAT including the hardness,tensile strength and elongation,and residual stress.Firstly,a brief introduction on the different forms of surface nanocrystallization is given to get a better understanding of the SMAT process and its advantages over other forms of surface treatments,and then the grain refinement mechanisms of materials by SMAT from the matrix region(base material)to the nanocrystallized layer are explained.The effects of fatigue,fracture,and wear of materials by the enhanced mechanical properties after SMAT are also discussed in detail.In addition,the various applications of SMAT ranging from automotive,photoelectric conversion,biomedical,diffusion,and 3 D-printing of materials are extensively discussed.The prospects and recent research trends in terms of mechanical properties of materials affected by SMAT are then summarized.
基金This work was supported by the National Key R&D Program of China(2017YFA0204403)the Major Program of the National Natural Science Foundation of China(51590892)+3 种基金the General Research Fund Research Grants Council(Hong Kong)(CityU 11209918)the Hong Kong Collaborative Research Fund Scheme(C4026-17W)the Hong Kong Theme-based Research Scheme(T13-402/17-N)the Shenzhen-Hong Kong cooperation zone for technology and innovation(HZQB-KCZYB-2020030).
文摘Over the past 30 years,additive manufacturing(AM)has developed rapidly and has demonstrated great potential in biomedical applications.AM is a materials-oriented manufacturing technology,since the solidification mechanism,architecture resolution,post-treatment process,and functional application are based on the materials to be printed.However,3D printable materials are still quite limited for the fabrication of bioimplants.In this work.2D/3D AM materials for bioimplants are reviewed.Furthermore,inspired by Tai Chi,a simple yet novel soft/rigid hybrid 4D AM concept is advanced to develop complex and dynamic biological structures in the human body based on 4D printing hybrid ceramic precursor/ceramic materials that were previously developed by our group.With the development of multi-material printing technology,the development of bioimplants and soft/rigid hybrid biological structures with 2D/3D/4D AM materials can be anticipated.
基金support provided by the Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project(HZQB-KCZYB-2020030)the Research Grants Council of Hong Kong(Project No:AoE/M-402/20.)+1 种基金the Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(YPML-2023050248)the Hong Kong Innovation and Technology Commission via the Hong Kong Branch of National Precious Metals Material Engineering Research Center.
文摘Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,limiting their practical applications.Herein,we propose a hierarchical salt-rejection(HSR)strategy to prevent salt precipitation during long-term evaporation while maintaining a rapid evaporation rate,even in high-salinity brine.The salt diffusion process is segmented into three steps—insulation,branching diffusion,and arterial transport—that significantly enhance the salt-resistance properties of the evaporator.Moreover,the HSR strategy overcomes the tradeoff between salt resistance and evaporation rate.Consequently,a high evaporation rate of 2.84 kg m^(-2) h^(-1),stable evaporation for 7 days cyclic tests in 20 wt%NaCl solution,and continuous operation for 170 h in natural seawater under 1 sun illumination were achieved.Compared with control evaporators,the HSR evaporator exhibited a>54%enhancement in total water evaporation mass during 24 h continuous evaporation in 20 wt%salt water.Furthermore,a water collection device equipped with the HSR evaporator realized a high water purification rate(1.1 kg m^(-2) h^(-1)),highlighting its potential for agricultural applications.
基金partially supported by Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project:HZQB-KCZYB-2020030Hong Kong Research Grants Council Collaborative Research Fund(Ref.C4026-17 W)+2 种基金Theme-based Research Scheme(Ref.T13402/17-N)funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 958457supported by the City U grant 9360161 and CRF grant C1027-14E。
文摘Dual-phase metallic glasses(DP-MGs),a special member of the MGs family,often reveal unusual strength and ductility,yet,their corrosion behaviors are not understood.Here,we developed a nanostructured Mg_(57)Zn_(36)Ca_(7)(at.%)DP-MG and uncovered its corrosion mechanism in simulated body fluid(SBF)at the near-atomic scale utilizing transmission electron microscope(TEM)and atom probe tomography(APT).The 10-nm-wide Ca-rich amorphous phases allow oxygen propagation into the DP-MG,resulting in a micrometer thick hydroxides/oxides layer.This dense corrosion layer protects the DP-MG from further corrosion,enabling a corrosion rate that is 77%lower than that of Mg(99.99%purity).
文摘1.Research and development(R&D)and the challenges of raw materials for medical additive manufacturing Raw materials for medical additive manufacturing have a wide range of commonalities that are also seen in many other fields,making them an important basis in the field of three-dimensional(3D)printing.Problems and challenges related to material types,powder properties,formability,viscoelasticity,and so forth also share common features.For example,many metal materials are used in the field of aviation,while metals,polymers,and inorganic materials are used in the field of biomedicine.The most widely used materials in biomedicine are biocompatible.Various homogeneous and non-homogeneous composites are also available for 3D printing,and impose an additional challenge in additive manufacturing;the use of heterogeneous composites in 3D printing is particularly challenging.
基金supported by the grants(Nos.9610478,9680314,7020013,and 1886921)the Start-Up Grant(No.9380100),ITC via the Hong Kong Branch of the National Precious Metals Material Engineering Research Center(NPMM)from City University of Hong Kong,the Research Grants Council of Hong Kong,China(No.AoE/P-701/20)the Science Technology and Innovation Committee of Shenzhen Municipality(Nos.JCYJ20200109143412311 and SGDX2020110309300301,“Preparation of single atoms on transition metal chalcogenides for electrolytic hydrogen evolution”,CityU).
文摘In the past decades,metal-containing nanomaterials have attracted increasing interests owing to their intriguing physicochemical properties and various promising applications.Recent research has revealed that the phase of metal-containing nanomaterials could significantly affect their properties and functions.In particular,nanomaterials with amorphous phase,which possess long-range disordered atomic arrangements,and the amorphous/crystalline heterophase nanostructures comprised of both amorphous and crystalline phases,have exhibited superior performance in various applications,e.g.,catalysis and energy storage.In this review,a brief overview of the recent progress on the wet-chemical synthesis and applications of amorphous and amorphous/crystalline heterophase metal-containing nanomaterials has been provided.Subsequently,on the basis of different categories of metal-containing nanomaterials,including metals,metal alloys,and metal compounds,their synthetic routes and promising applications will be highlighted.Finally,current challenges and some personal perspectives in this emerging research field will be proposed.
基金National Natural Science Foundation of China(No.22008251)Guangdong Basic and Applied Basic Research Foundation(No.2022A1515010318)Shenzhen Science and Technology Program(No.JCYJ20220531095813031).
文摘Improving the catalytic activity of non-noble metal single atom catalysts(SACs)has attracted considerable attention in materials science.Although optimizing the local electronic structure of single atom can greatly improve their catalytic activity,it often involves in-plane modulation and requires high temperatures.Herein,we report a novel strategy to manipulate the local electronic structure of SACs via the modulation of axial Co-S bond anchored onto graphitic carbon nitride(C_(3)N_(4))at room temperature(RT).Each Co atom is bonded to four N atoms and one S atom(Co-(N,S)/C_(3)N_(4)).Owing to the greater electronegativity of S in the Co-S bond,the local electronic structure of the Co atoms is available to be controlled at a relatively moderate level.Consequently,when employed for the photocatalytic hydrogen evolution reaction,the adsorption energy of intermediate hydrogen(H*)on the Co atoms is remarkably low.In the presence of the Co-(N,S)/C_(3)N_(4)SACs,the hydrogen evolution rates reach up to 10 mmol/(g·h),which is nearly 10 and 2.5 times greater than the rates in the presence of previously reported transition metal/C_(3)N_(4)and noble platinum nanoparticles(PtNPs)/C_(3)N_(4)catalysts,respectively.Attributed to the tailorable axial Co-S bond in the SAC,the local electronic structure of the Co atoms can be further optimized for other photocatalytic reactions.This axial coordination engineering strategy is universal in catalyst designing and can be used for a variety of photocatalytic applications.
基金financial support of National Natural Science Foundation of China(No.51971149)the funding from Science and Technology Innovation Commission of Shenzhen(Nos.KQJSCX20180328095612712,GJHZ20190822095418365)+1 种基金Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515110869 and 2019A1515110515)Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project(No.HZQB-KCZYB-2020030)。
文摘As a revolutionary industrial technology,additive manufacturing creates objects by adding materials layer by layer and hence can fabricate customized components with an unprecedented degree of freedom.For metallic materials,unique hierarchical microstructures are constructed during additive manufacturing,which endow them with numerous excellent properties.To take full advantage of additive manufacturing,an in-depth understanding of the microstructure evolution mechanism is required.To this end,this review explores the fundamental procedures of additive manufacturing,that is,the formation and binding of melt pools.A comprehensive processing map is proposed that integrates melt pool energy-and geometry-related process parameters together.Based on it,additively manufactured microstructures are developed during and after the solidification of constituent melt pool.The solidification structures are composed of primary columnar grains and fine secondary phases that form along the grain boundaries.The post-solidification structures include submicron scale dislocation cells stemming from internal residual stress and nanoscale precipitates induced by intrinsic heat treatment during cyclic heating of adjacent melt pool.Based on solidification and dislocation theories,the formation mechanisms of the multistage microstructures are thoroughly analyzed,and accordingly,multistage control methods are proposed.In addition,the underlying atomic scale structural features are briefly discussed.Furthermore,microstructure design for additive manufacturing through adjustment of process parameters and alloy composition is addressed to fulfill the great potential of the technique.This review not only builds a solid microstructural framework for metallic materials produced by additive manufacturing but also provides a promising guideline to adjust their mechanical properties.
基金J.L.acknowledges the supports from the National Key R&D Program of China(Project No.2017YFA0204403)Research Grants Council of the Hong Kong Special Administrative Region(Grant No.CityU-11247516)+3 种基金the Hong Kong Collaborative Research Fund(CRF)Scheme(C4028-14G)Guangdong Science and Technology Department(Ref:2014B050504003)SZSTI(Ref:ZDSYS201602291653165)X.H.is grateful for the support from the Research Grants Council of the Hong Kong Special Administrative Region(Grant No.CityU-11204414).
文摘The recent studies on nanotwinned(NT)and hierarchical nanotwinned(HNT)face-centered cubic(FCC)metals are presented in this review.The HNT structures have been supposed as a kind of novel structure to bring about higher strength/ductility than NT counterparts in crystalline materials.We primarily focus on the recent developments of the experimental,atomistic and theoretical studies on the NT and HNT structures in the metallic materials.Some advanced bottom-up and top-down techniques for the fabrication of NT and HNT structures are introduced.The deformation induced HNT structures are available by virtue of severe plastic deformation(SPD)based techniques while the synthesis of growth HNT structures is so far almost unavailable.In addition,some representative molecular dynamics(MD)studies on the NT and HNT FCC metals unveil that the nanoscale effects such as twin spacing,grain size and plastic anisotropy greatly alter the performance of NT and HNT metals.The HNT structures may initiate unique phenomena in comparison with the NT ones.Furthermore,based on the phenomena and mechanisms revealed by experimental and MD simulation observations,a series of theoretical models have been proposed.They are effective to describe the mechanical behaviors of NT and HNT metals within the applicable scope.So far the development of manufacturing technologies of HNT structures,as well as the studies on the effects of HNT structures on the properties of metals are still in its infancy.Further exploration is required to promote the design of advanced materials.
基金H.Z.thanks the support from ITC via the Hong Kong Branch of National Precious Metals Material Engineering Research Center(NPMM),the Research Grants Council of Hong Kong(No.11301721)the Start-Up Grant(No.9380100)the grants(No.1886921)from the City University of Hong Kong.This research used 7-BM of the National Synchrotron Light Source II,a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract(No.DE-SC0012704).
文摘Amorphous nanomaterials with long-range disordered structures could possess distinct properties and promising applications,especially in catalysis,as compared with their conventional crystalline counterparts.It is imperative to achieve the controlled preparation of amorphous noble metal-based nanomaterials for the exploration of their phase-dependent applications.Here,we report a facile wet-chemical reduction strategy to synthesize various amorphous multimetallic Pd-based nanomaterials,including PdRu,PdRh,and PdRuRh.The phase-dependent catalytic performances of distinct Pd-based nanomaterials towards diverse catalytic applications have been demonstrated.Specifically,the usage of PdRu nanocatalysts with amorphous and crystalline face-centered cubic(fcc)phases can efficiently switch the ring-opening route of styrene oxide to obtain different products with high selectivity through alcoholysis reaction and hydrogenation reaction,respectively.Moreover,when used as an electrocatalyst for hydrogen evolution reaction(HER),the synthesized amorphous PdRh nanocatalyst exhibits low overpotential and high turnover frequency values,outperforming its crystalline fcc counterpart and most of the reported Pd-based HER electrocatalysts.
基金support from the Research Grants Council of Hong Kong(GRF project no.11301721)ITC via the Hong Kong Branch of the National Precious Metals Material Engineering Research Center(NPMM),a start-up grant(project no.9380100)grants(project nos.7020054,9678272,and 1886921)from the City University of Hong Kong。
文摘As an important parameter of crystalline materials,the crystal phase describes the periodic atomic arrangement in their structures.For some monoelemental materials,e.g.,carbon and phosphorus,they can exist in more than one crystal phase.The different crystal phases of monoelemental materials result in different physicochemical properties and functions.Therefore,engineering the crystal phase of monoelemental materials gives an effective strategy to modulate their properties and functions.Conventionally,the crystal phase of monoelemental materials can be altered under some harsh conditions,e.g.,high temperature and high pressure.Recently,with the rapid development of nanotechnology,various monoelemental materials with unconventional crystal phases have been well developed on the nanoscale.For example,our group has successfully achieved the synthesis of Au nanomaterials with unconventional hexagonal close-packed(hcp)2H and 4H phases by wetchemical methods,which exhibit distinct optical properties as well as outstanding electrocatalytic performance when compared to those with a thermodynamically stable facecentered cubic(fcc)phase.In this Account,we give a comprehensive overview of the recent development of monoelemental nanomaterials with unconventional crystal phases and their crystal-phase-dependent properties and applications.We first introduce the typical strategies for the synthesis of monoelemental nanomaterials with unconventional crystal phases.By using a wet-chemical reduction method,template-assisted method,and thermal annealing method,monoelemental nanomaterials with unconventional crystal phases can be directly prepared.Besides,unconventional-phase monoelemental nanomaterials can also be obtained via the phase transformation from materials with conventional crystal phases under specific conditions.In addition,some other methods have also been reported for preparing monoelemental nanomaterials with unconventional crystal phases,such as controlled crystallization of amorphous structure,the chemical vapor transport(CVT)method,electrodeposition,galvanic replacement,sputter-deposition,and so on.Subsequently,we summarize the unique structural stability and magnetic,electronic,optical,and other properties of the obtained monoelemental nanomaterials with unconventional crystal phases.We also highlight their promising applications in catalysis and batteries.Finally,we present our personal perspectives on the challenges and future opportunities in this important research field.
基金financially supported by the National Key R&D Program of China(Project No.2017YFA0204403)the Shenzhen Virtual University Park(R-IND1710)+5 种基金the Innovation and Technology Commission via the Hong Kong Branch of National Precious Metals Material Engineering Research Centersupported by the Research Grants Council of the Hong Kong Special Administrative Region,China(No.CityU 11209914)General Research Fund of Hong Kong(No.CityU 11247516)the National Natural Science Foundation of China(No.51301147)supported by Province-Institute/Province-College Cooperation Project underGrant No.2017IB016The financial support from SZSTI(Ref:JSGG20141020103826038)
文摘Hall-Petch relation was widely applied to evaluate the grain size effect on mechanical properties of metallic material. However, the sample size effect on the Hall-Petch relation was always ignored. In the present study, the mechanical test and microstructure observation were performed to investigate the combined effects of grain and sample sizes on the deformation behaviors of gold microwires. The polycrystalline gold microwires with diameter of 16 ?m were annealed at temperatures from 100°C to 600°C, leading to different ratios(t/d) of wire diameter(t) to grain size(d) from 0.9 to 16.7. When the t/d was lower than 10, the yield stress dropped fast and deviated from the Hall-Petch relation. The free-surface grains played key role in the yield stress softening, and the volume fraction of free-surface grains increased with the t/d decreasing. Furthermore, the effects of t/d on work-hardening behaviors and fracture modes were also studied. With t/d value decreasing from 17 to 3.4, the samples exhibited necking fracture and the dislocation pile-ups induced work-hardening stage was gradually activated.With the t/d value further decreasing(t/d < 3.4), the fracture mode turned into shear failure, and the work-hardening capability lost. As the gold microwire for wire bonding is commonly applied in the packaging of integrated circuit chips, and the fabrication of microwire suffers multi-pass cold-drawing and annealing treatments to control the grain size. The present study could provide instructive suggestion for gold microwire fabrication and bonding processes.
基金MOE under AcRF Tier 2(Nos.MOE2016-T2-2-103 and MOE2017-T2-1-162)NTU under Start-Up Grant(No.M4081296.070.500000)in Singapore+2 种基金We would like to acknowledge the Facility for Analysis,Characterization,Testing and Simulation,Nanyang Technological University,Singapore,for use of their electron microscopy and X-ray facilities.Z.X.F.and H.Z.thank the financial support from ITC via Hong Kong Branch of National Precious Metals Material Engineering Research Center(NPMM)acknowledge the start-up grants(Nos.9380100,9610480 and 7200651)grants(Nos.9610478 and 1886921)in City University of Hong Kong.
文摘Crystal phase can greatly affect the physicochemical properties and applications of nanomaterials.However,it stil remains a great challenge to synthesize nanostructures with the same composition and morphology but different phases in order to explore the phase-dependent properties and applications.Herein,we report the crystal phase-controlled synthesis of PtCu alloy shells on 4H Au nanoribbons(NRBs),referred to as 4H-Au NRBs,to form the 4H-Au@PtCu core-shell NRBs.By tuning the thickness of PtCu,4H-PtCu and face-centered cubic(cc)phase PICu(cc-PtCu)alloy shells are successtully grown on the 4H-Au NRB cores.This thickness-dependent phase-controlled growth strategy can also be used to grow PtCo alloys with 4H or fcc phase on 4H-Au NRBs.Significantly,when used as electrocatalysts for the ethanol oxidation reaction(EOR)in alkaline media,the 4H-Au@4H-PtCu NRBs show much better EOR performance than the 4H-Au@fcc-PtCu NRBs,and both of them possess superior performance compared to the commercial Pt black.Our study provides a strategy on phase-contolled synthesis of nanomaterials used for crystal phase-dependent applications.
基金supported by Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project:HZQB-KCZYB-2020030Health@InnoHK(Hong Kong Centre for Cerebro-cardiovascular Health Engineering(COCHE),Innovation and Technology Commission,the Government of the Hong Kong Special Administrative Region of the People’s Republic of China,the Innovation and Technology Commission of HKSAR through Hong Kong Branch of National Precious Metals Material Engineering Research Center(NPMM),the City University of Hong Kong(No.7005077).
文摘Mineral hydrogels have caught a lot of attention for their strong competency as artificial skin-like materials.Nonetheless,it remains a great difficulty in fulfilling in one hydrogel system a range of key functionalities that are needed for practical artificial skin applications,i.e.,to be biocompatible,strain-sensitive,ion-conductive,elastic and robust,anti-swelling,and anti-freezing.Here we present a such type of versatile hydrogel that is not only capable to deliver all the above-mentioned key functionalities but also highly stable.This novel hydrogel is constructed by introducing a gelatinous and amorphous multi-ionic biomineral(denoted as Mg-ACCP,containing Mg^(2+),Ca^(2+),CO_(3)^(2−),and PO_(4)^(3−))into the network of biocompatible polyvinyl alcohol(PVA)and sodium alginate(SA).The presence of Mg^(2+)and PO_(4)^(3−)in this hydrogel helps prohibit the crystallization of the biominerals,leading to significantly improved stability.The hydrogel thus obtained delivers excellent mechanical performance due to the chelation between the mineral ions and the organic matrix,and high sensitivity even to subtle pressure and strain applied,such as slight finger bending and gentle tapping.Furthermore,the novel hydrogel features high ionic conductivity,high resistance to swelling,and extraordinary anti-freezing property,holding great promise for applications in different practical scenarios,particularly in aqueous or cold environments.
基金support from ITC via the Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM)the Research Grants Council of Hong Kong (AoE/P-701/ 20)+4 种基金the Start-Up Grant (9380100)the grants from the City University of Hong Kong (9610478, 9680314, 7020013, 1886921)the Science Technology and Innovation Committee of Shenzhen Municipality (JCYJ20200109143412311, SGDX2020110309300301, “Preparation of single atoms on transition metal chalcogenides for electrolytic hydrogen evolution”, City U)funding support from the StartUp Grant (7200656, 9610482)Grant from the City University of Hong Kong (7020013)。
文摘Cost-effective, rapid, and accurate virus detection technologies play key roles in reducing viral transmission. Prompt and accurate virus detection enables timely treatment and effective quarantine of virus carrier, and therefore effectively reduces the possibility of large-scale spread. However, conventional virus detection techniques often suffer from slow response, high cost or sophisticated procedures. Recently, two-dimensional(2D) materials have been used as promising sensing platforms for the highperformance detection of a variety of chemical and biological substances. The unique properties of 2D materials, such as large specific area, active surface interaction with biomolecules and facile surface functionalization, provide advantages in developing novel virus detection technologies with fast response and high sensitivity. Furthermore, 2D materials possess versatile and tunable electronic, electrochemical and optical properties, making them ideal platforms to demonstrate conceptual sensing techniques and explore complex sensing mechanisms in next-generation biosensors. In this review, we first briefly summarize the virus detection techniques with an emphasis on the current efforts in fighting again COVID-19. Then, we introduce the preparation methods and properties of 2D materials utilized in biosensors, including graphene, transition metal dichalcogenides(TMDs) and other 2D materials. Furthermore, we discuss the working principles of various virus detection technologies based on emerging 2D materials, such as field-effect transistor-based virus detection, electrochemical virus detection, optical virus detection and other virus detection techniques. Then, we elaborate on the essential works in 2D material-based high-performance virus detection. Finally, our perspective on the challenges and future research direction in this field is discussed.
基金This work was jointly supported by Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project(No.HZQB-KCZYB-2020030)the National Key R&D Program of China(Project No.2017YFA0204403)Innovation and Technology Commission of HKSAR through Hong Kong Branch of National Precious Metals Material Engineering Research Centre and Shenzhen Science and Technology Innovation Committee(No.JCYJ20200109113212238).
文摘Fabrication of single-crystalline metal-organic framework(MOF)hollow nanostructures with two-dimensional(2D)morphologies is a challenging task.Herein,twin-like MOF nanobricks,a quasi-hollow 2D architecture,with multi-metal nodes and replaceable organic ligands,are uniformly and firmly grown on conductive Ni foam through a generic one-pot approach.The formation process of twin-like MOF nanobricks mainly includes selective epitaxial growth of Fe-rich MOF layer and simultaneously dissolution of the pre-formed Ni-rich metal-organic frameworks(MOFs),all of which can be ascribed to a special self-templated mechanism.The fantastic structural merits of twin-like MOF nanobrick arrays,featuring highly exposed active sites,remarkable electrical conductivity,and hierarchical porosities,enable this material for efficient electrocatalysis.Using bimetallic NiFe-MOFs grown on Ni foam as an example,the resultant twin-like nanobrick arrays can be directly utilized as three-dimensional(3D)integrated electrode for high-performance water oxidation in 1 M KOH with a low overpotential,fast reaction kinetics(28.5 mV·dec^(-1)),and superb stability.Interestingly,the unstable NiFe-MOFs were served as an oxygen evolution reaction(OER)pre-catalyst and the single-crystalline NiFe-MOF precursor can be in-situ topochemically regulated into porous and lowcrystalline NiFeOx nanosheets during the OER process.This work extends the hollowing strategy to fabricate hollow MOFs with 2D architectures and highlights their direct utilization for advanced electrocatalysis.
基金support from the Start-up Fund(BDC2)and Research Institute for Advanced Manufacturing(RIAM)Fund(CD4D)from the Hong Kong Polytechnic University.Y.C.thanks the support from Start-up Fund(Project No.4930977)the Direct Grant for Research(Project No.4053444)from the Chinese University of Hong Kong+3 种基金H.Z.thanks the support from ITC via the Hong Kong Branch of National Precious Metals Material Engineering Research Center(NPMM),the Research Grants Council of Hong Kong(GRF Project No.11301721)the Start-Up Grant(Project No.9380100)the grants(Project Nos.7020054,9678272,and 1886921)from the City University of Hong Kongthe Science Technology and Innovation Committee of Shenzhen Municipality(“Preparation of single atoms on transition metal chalcogenides for electrolytic hydrogen evolution”,CityU),and the Project 52131301 supported by NSFC.
文摘The electrochemical CO_(2) reduction reaction(CO_(2)RR)offers a green and sustainable process to convert CO_(2) into valuable chemical stocks and fuels.Metal is one of the most promising types of catalysts to drive an efficient and selective CO_(2)RR.The catalytic performance of metal nanocatalysts is strongly dependent on their structural features.Recently,phase engineering of nanomaterials(PEN)has emerged as a prominent tactic to regulate the catalytic performance of metal nanocatalysts for the CO_(2)RR.A broad range of metal nanocatalysts with conventional and unconventional crystal phases has been developed,and remarkable achievements have been made.This review summarizes the most recent developments in phase engineering of metal nanocatalysts for the electrochemical CO_(2)RR.We first introduce the different crystal phases of metal nanocatalysts used in the CO_(2)RR and then discuss various synthetic strategies for unconventional phases of metal nanocatalysts.After that,detailed discussions of metal nanocatalysts with conventional and unconventional phases,including amorphous phases,are presented.Finally,the challenges and perspectives in this emerging area are discussed.
文摘Layered van der Waals(vdW)materials,consisting of atomically thin layers,are of paramount importance in physics,chemistry,and materials science owing to their unique properties and various promising applications.However,their fast and large‐scale growth via a general approach is still a big challenge,severely limiting their practical implementations.Here,we report a universal method for rapid(~60 min)and large‐scale(gram scale)growth of phase‐pure,high‐crystalline layered vdW materials from their elementary powders via microwave plasma heating in sealed ampoules.This method can be used for growth of 30 compounds with different components(binary,ternary,and quaternary)and properties.The ferroelectric and transport properties of mechanically exfoliated flakes validate the high crystal quality of the grown materials.Our study provides a general strategy for the fast and large‐scale growth of layered vdW materials with appealing physiochemical properties,which could be used for various promising applications.
文摘Comprehensive understanding of the structural/morphology stability of ultrathin (diameter 〈 10 nm) gold nanowires under real service conditions (such as under Joule heating) is a prerequisite for the reliable implementation of these emerging building blocks into functional nanoelectronics and mechatronics systems. Here, by using the in situ transmission electron microscopy (TEM) technique, we discovered that the Rayleigh instability phenomenon exists in ultrathin gold nanowires upon moderate heating. Through the controlled electron beam irradiation-induced heating mechanism (with 〈 100 ~C temperature rise), we further quantified the effect of electron beam intensity and its dependence on Rayleigh instability in altering the geometry and morphology of the ultrathin gold nanowires. Moreover, in situ high-resolution TEM (HRTEM) observations revealed surface atomic diffusion process to be the dominating mechanism for the morphology evolution processes. Our results, with unprecedented details on the atomic-scale picture of Rayleigh instability and its underlying physics, provide critical insights on the thermal/structural stability of gold nanostructures down to a sub-10 nm level which may pave the way for their interconnect applications in future ultra- large-scale integrated ciroaits.
文摘Integrating functional materials to form heterostructures with novel,sophisticated architectures has attracted extensive interest in chemistry and materials science^([1]).Heterostructures are expected to exhibit superior electrical,thermal,optical and magnetic properties due to the synergistic effect of their different components.Therefore,the rational design and preparation of heterostructures with controlled compositions,dimensions.