Transition metal phosphide(TMP) based electrocatalysts possessing special crystal and electronic structures attract broad attention in the field of electrocatalysis.Immense effort is made to optimize TMP catalysts aim...Transition metal phosphide(TMP) based electrocatalysts possessing special crystal and electronic structures attract broad attention in the field of electrocatalysis.Immense effort is made to optimize TMP catalysts aiming to satisfy the electrochemical catalysis performance.In this work,an environmentally friendly in situ green phosphating strategy and spatial limiting effect of the RuCo precursor is employed to fabricate the ruthenium nanoclusters anchored on cobalt phosphide hollow microspheres(Ru NCs/Co_(2)P HMs).The obtained Ru NCs/Co_(2)P HMs electrocatalysts exhibit high hydrogen evolution reaction(HER) activity at wide pH ranges,which require an overpotential of 77 mV to achieve the current density of 10 mA/cm^(2) in 0.5 mol/L H_(2)SO_(4) and 118 mV in 1.0 mol/L KOH.Besides,the multifunctional Ru NCs/Co_(2)P HMs exhibit good oxygen evolution reaction(OER) activity with an overpotential of 197 mV to reach the current density of 10 mA/cm^(2) in 0.5 mol/L H_(2)SO_(4),which is below that of the commercial RuO_(2) electrocatalyst(248 mV).A two-electrode electrolyzer is assembled as well,in acid electrolyte,it achieves a current density of 10 mA/cm^(2) at a voltage of 1.53 V,which is superior to that of the benchmark of precious metal-based electrolyzer(1.58 V).展开更多
Semiconductor nanomaterial-based epitaxial heterostructures with precisely controlled compositions and morphologies are of great importance for various applications in optoelectronics,thermoelectrics,and catalysis.Unt...Semiconductor nanomaterial-based epitaxial heterostructures with precisely controlled compositions and morphologies are of great importance for various applications in optoelectronics,thermoelectrics,and catalysis.Until now,various kinds of epitaxial heterostructures have been constructed.In this minireview,we will first introduce the synthesis of semiconductor nanomaterial-based epitaxial heterostructures by wet-chemical methods.Various architectures based on different kinds of seeds or templates are illustrated,and their growth mechanisms are discussed in detail.Then,the applications of epitaxial heterostructures in optoelectronics,catalysis,and thermoelectrics are described.Finally,we provide some challenges and personal perspectives for the future research directions of semiconductor nanomaterial-based epitaxial heterostructures.展开更多
As one of the important materials,nanocrystalline Au(n-Au)has gained numerous interests in recent decades owing to its unique properties and promising applications.However,most of the current n-Au thin films are suppo...As one of the important materials,nanocrystalline Au(n-Au)has gained numerous interests in recent decades owing to its unique properties and promising applications.However,most of the current n-Au thin films are supported on substrates,limiting the study on their mechanical properties and applications.Therefore,it is urgently desired to develop a new strategy to prepare nAu materials with superior mechanical strength and hardness.Here,a hard n-Au material with an average grain size of~40 nm is prepared by cold-forging of the unique Au nanoribbons(NRBs)with unconventional 4H phase under high pressure.Systematic characterizations reveal the phase transformation from 4H to face-centered cubic(fcc)phase during the cold compression.Impressively,the compressive yield strength and Vickers hardness(HV)of the prepared n-Au material reach~140.2 MPa and~1.0 GPa,which are 4.2 and 2.2 times of the microcrystalline Au foil,respectively.This work demonstrates that the combination of high-pressure cold-forging and the in-situ 4H-to-fcc phase transformation can effectively inhibit the grain growth in the obtained n-Au materials,leading to the formation of novel hard n-Au materials.Our strategy opens up a new avenue for the preparation of nanocrystalline metals with superior mechanical property.展开更多
Controlled synthesis of transition metal dichalcogenide (TMD) monolayers with unusual crystal phases has attracted increasing attention due to their promising applications in electrocatalysis.However,the facile and la...Controlled synthesis of transition metal dichalcogenide (TMD) monolayers with unusual crystal phases has attracted increasing attention due to their promising applications in electrocatalysis.However,the facile and large-scale preparation of TMD monolayers with high-concentration unusual crystal phase still remains a challenge.Herein,we report the synthesis of MoX2 (X =Se or S) monolayers with high-concentration semimetallic 1T'phase by using the 4H/face-centered cubic (fcc)-Au nanorod as template to form the 4H/fcc-Au@MoX2 nanocomposite.The concentrations of 1T'phase in the prepared MoSe2 and MoS2 monolayers are up to 86% and 81%,respectively.As a proof-of-concept application,the obtained Au@MoS2 nanocomposite is used for the electrocatalytic hydrogen evolution reaction (HER) in acid medium,exhibiting excellent performance with a low overpotential of 178 mV at the current density of 10 mNcm^2,a small Tafel slope of 43.3 mV/dec,and excellent HER stability.This work paves a way for direct synthesis of TMD monolayers with high-concentration of unusual crystal phase for the electrocatalytic application.展开更多
In the controlled synthesis of noble metal nanostructures using wet-chemical methods, normally, metal salts/complexes are used as precursors, and surfactants/ligands are used to tune/stabilize the morphology of nanost...In the controlled synthesis of noble metal nanostructures using wet-chemical methods, normally, metal salts/complexes are used as precursors, and surfactants/ligands are used to tune/stabilize the morphology of nanostructures. Here, we develop a facile electrochemical method to directly convert Pt wires to Pt concave icosahedra and nanocubes on carbon paper through the linear sweep voltammetry in a classic three-electrode electrochemical cell. The Pt wire, carbon paper and Ag/AgCl(3 mol L-1 KCl) are used as the counter, working and reference electrodes, respectively.Impressively, the formed Pt nanostructures exhibit better electrocatalytic activity towards the hydrogen evolution compared to the commercial Pt/C catalyst. This work provides a simple and effective way for direct conversion of Pt wires into well-defined Pt nanocrystals with clean surface. We believe it can also be used for preparation of other metal nanocrystals,such as Au and Pd, from their bulk materials, which could exhibit various promising applications.展开更多
It is the nature of crystals to exist in different polymorphs. The recent emergence of two-dimensional(2 D) materials has evoked the discovery of a number of new crystal phases that are different from their bulk struc...It is the nature of crystals to exist in different polymorphs. The recent emergence of two-dimensional(2 D) materials has evoked the discovery of a number of new crystal phases that are different from their bulk structures at ambient conditions, and revealed novel structure-dependent properties, which deserve in-depth understanding and further exploration. In this contribution, we review the recent development of crystal phase control in 2 D materials, including group V and VI. transition metal dichalcogenides(TMDs), group IVA metal chalcogenides and noble metals. For each group of materials, we begin with introducing the various existing crystal phases and their structure-related properties, followed by a detailed discussion on factors that influence these crystal structures and thus the possible strategies for phase control. Finally, after summarizing the whole paper, we present the challenges and opportunities in this research direction.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
Developing electrocatalysts with high performance and low cost for the oxygen evolution reaction(OER)is of great importance for fabricating renewable energy storage and conversion devices.Here,a series of boron-doped ...Developing electrocatalysts with high performance and low cost for the oxygen evolution reaction(OER)is of great importance for fabricating renewable energy storage and conversion devices.Here,a series of boron-doped graphene(BG)-supported bimetallic oxides of Co and Ni were obtained and served as OER electrocatalysts.Surprisingly,the annealed Co-Ni-Ox/BG with a Co/Ni ratio of 1:1 exhibits high performance toward oxygen evolution in alkaline electrolyte.The overpotential is only 310 mV at the current density of 10 mA cm-2,superior to many mono-metallic oxides reported before,and even comparable to the commercial RuO2.The regulation of charge distribution in bimetallic oxides and the strong synergistic coupling effects together contribute to the superior electrocatalytic performance of the Co-Ni-Ox/BG toward OER.This study also offers several effective ways to design high-performance OER electrocatalysts for water splitting.展开更多
Mid-infrared(MIR)light-emitting devices play a key role in optical communications,thermal imaging,and material analysis applications.Two-dimensional(2D)materials offer a promising direction for next-generation MIR dev...Mid-infrared(MIR)light-emitting devices play a key role in optical communications,thermal imaging,and material analysis applications.Two-dimensional(2D)materials offer a promising direction for next-generation MIR devices owing to their exotic optical properties,as well as the ultimate thickness limit.More importantly,van der Waals heterostructures-combining the best of various 2D materials at an artificial atomic level-provide many new possibilities for constructing MIR light-emitting devices of large tuneability and high integration.Here,we introduce a simple but novel van der Waals heterostructure for MIR light-emission applications built from thin-film BP and transition metal dichalcogenides(TMDCs),in which BP acts as an MIR light-emission layer.For BP–WSe_(2) heterostructures,an enhancement of~200% in the photoluminescence intensities in the MIR region is observed,demonstrating highly efficient energy transfer in this heterostructure with type-Ⅰ band alignment.For BP-MoS_(2) heterostructures,a room temperature MIR light-emitting diode(LED)is enabled through the formation of a vertical PN heterojunction at the interface.Our work reveals that the BP-TMDC heterostructure with efficient light emission in the MIR range,either optically or electrically activated,provides a promising platform for infrared light property studies and applications.展开更多
The rational design and synthesis of multimetallic nanostructures(NSs)with rich defects are of significant importance for their diverse applications,including their promising usage as high-efficiency catalysts for alc...The rational design and synthesis of multimetallic nanostructures(NSs)with rich defects are of significant importance for their diverse applications,including their promising usage as high-efficiency catalysts for alcohol oxidation reaction as a fuel source.Here,we report the synthesis of defect-rich,candied haws-shaped AuPtNi NSs using presynthesized gold(Au)nanowires as templates.The ternary AuPtNi NSs possess rich defects such as twins,stacking faults,and atomic steps.Impressively,the AuPtNi NSs exhibited excellent mass and specific activities toward methanol and ethanol oxidation reactions under acidic conditions.Our current work paves the way for the rational design and controlled synthesis of defect-rich multimetallic NSs to boost their performances in catalytic reactions.展开更多
The increasing demand of clean water and ef- fective way to recycle industrial wastewater has offered a new application for carbon-based three-dimensional （3D） porous networks as sorbents due to their superior sorpt...The increasing demand of clean water and ef- fective way to recycle industrial wastewater has offered a new application for carbon-based three-dimensional （3D） porous networks as sorbents due to their superior sorption abilities. Through the surface modification and hybridization with functional materials, the physical and chemical properties of the 3D carbon-based materials can be engineered. In this work, graphene-MoS2 aerogels （GMAs） with bulky shape are synthesized via a one-pot hydrothermal method. The obtained GMAs show quick sorption rate and high sorption capacity towards a wide variety of contaminants. The sorption covers not only organic solvents or organic dyes, but also toxic heavy metals ions such as Hg2＋ and Pb2＋. More importantly, the sorption capacity towards metal ions can be optimized by simply changing the loading amount of MoS2.展开更多
The layered transition metal dichalcogenides(TMDs)and transition metal phosphides are low-cost,earth-abundant,and robust electrocatalysts for hydrogen evolution reaction(HER).Integrating them into hybrid nanostructure...The layered transition metal dichalcogenides(TMDs)and transition metal phosphides are low-cost,earth-abundant,and robust electrocatalysts for hydrogen evolution reaction(HER).Integrating them into hybrid nanostructures is potentially promising to further boost the catalytic activity toward HER based on their synergistic effects.Herein,we report a general method for the synthesis of a series of MoSe_(2)-based hybrid nanostructures,including MoSe_(2)-Ni_(2)P,MoSe_(2)-Co_(2)P,MoSe_(2)-Ni,MoSe_(2)-Co,and MoSe_(2)-NiS,by postgrowth of Ni_(2)P,Co_(2)P,Ni,Co,and NiS nanostructures on the presynthesized MoSe_(2) nanosheet-assembled nanospheres,respectively,via a colloidal synthesis method.As a proof-of-concept application,the as-synthesized hybrid nanostructures are used as electrocatalysts for HER,exhibiting high activity and stability in acidic media.Among them,the MoSe_(2)-Co_(2)P composite shows the highest HER activity with an overpotential of 167 mV at 10 mA cm^(-2).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
Lateral hetero-junctions are considered as potential candidate for building blocks in modern electronics and optoelectronics,however,the construction of which remains a challenge.In this work,by using a laser-assisted...Lateral hetero-junctions are considered as potential candidate for building blocks in modern electronics and optoelectronics,however,the construction of which remains a challenge.In this work,by using a laser-assisted manufacture technique,WSe2/WO3-x hetero-junction and monolayer/trilayer WSe2 homo-junction with Schottky diode like behavior are fabricated,both of which present competitive performance for photodetection and power generation in a wide range of wavelengths from ultraviolet to infrared,with maximum photoresponsivity of 10 A/W,external quantum efficiency of 14%,and power conversion efficiency of 1.3%.Combined with Kelvin probe microscopy and electrical transport measurements,it is demonstrated that the barrier-induced built-in electric field at WSe2/WO3-x interface,and the energy band discontinuities at the monolayer/trilayer WSe2 interface facilitate the separation of photo-generated electron-hole pairs.Our work provides a solid step towards the controllable construction of lateral junctions by laser-assisted manufacture for exploiting van der Waals materials-based novel electronic and optoelectronic applications.展开更多
Electrochemical CO_(2) reduction reaction(CO_(2)RR)is an attractive pathway for closing the anthropogenic carbon cycle and storing intermittent renewable energy by converting CO_(2) to valuable chemicals and fuels.The...Electrochemical CO_(2) reduction reaction(CO_(2)RR)is an attractive pathway for closing the anthropogenic carbon cycle and storing intermittent renewable energy by converting CO_(2) to valuable chemicals and fuels.The production of highly reduced carbon compounds beyond CO and formate,such as hydrocarbon and oxygenate products with higher energy density,is particularly desirable for practical applications.However,the productivity towards highly reduced chemicals is typically limited by high overpotential and poor selectivity due to the multiple electron-proton transfer steps.Tandem catalysis,which is extensively utilized by nature for producing biological macromolecules with multiple enzymes via coupled reaction steps,represents a promising strategy for enhancing the CO_(2)RR performance.Improving the efficiency of CO_(2)RR via tandem catalysis has recently emerged as an exciting research frontier and achieved significant advances.Here we describe the general principles and also considerations for designing tandem catalysis for CO_(2)RR.Recent advances in constructing tandem catalysts,mainly including bimetallic alloy nanostructures,bimetallic heterostructures,bimetallic core-shell nanostructures,bimetallic mixture catalysts,metal-metal organic framework(MOF)and metal-metallic complexes,metal-nonmetal hybrid nanomaterials and copper-free hybrid nanomaterials for boosting the CO_(2)RR performance are systematically summarized.The study of tandem catalysis for CO_(2)RR is still at the early stage,and future research challenges and opportunities are also discussed.展开更多
The rational design and synthesis of hybrid-type electrode nanomaterials are significant for their diverse applications,including their potential usage as high-efficiency nanoarchitectures for supercapacitors(SCs)as a...The rational design and synthesis of hybrid-type electrode nanomaterials are significant for their diverse applications,including their potential usage as high-efficiency nanoarchitectures for supercapacitors(SCs)as a class of promising energy-storage systems for powering next-generation electric vehicles and electronic devices.Here,we reported a facile and controllable synthesis of core-shell Ni_(3)S_(2)@NiWO_(4)nanoarrays to fabricate a freestanding electrode for hybrid SCs.Impressively,the as-prepared freestanding Ni_(3)S_(2)@NiWO_(4)electrode presents an ultrahigh areal capacity of 2032μA h cm^(-2)at 5 mA cm^(-2),and a capacity retention of 63.6%even when the current density increased up to 50 mA cm^(-2).Remarkably,the Ni_(3)S_(2)@NiWO_(4)nanoarraybased hybrid SC delivers a maximum energy density of 1.283 mW h cm^(-2)at 3.128 mW cm^(-2)and a maximum power density of 41.105 mW cm^(-2)at 0.753 mW h cm^(-2).Furthermore,the hybrid SC exhibits a capacity retention of 89.6%even after continuous 10,000 cycles,proving its superior stability.This study provides a facile pathway to rationally design a variety of core-shell metal nanostructures for high-performance energy storage devices.展开更多
Hierarchical structures with different length scales,which appear in many animals and plants,play important roles in their structural and functional integrity[1,2].These structures endow their host animals and plants ...Hierarchical structures with different length scales,which appear in many animals and plants,play important roles in their structural and functional integrity[1,2].These structures endow their host animals and plants with intriguing properties including super-hydrophobicity,reversible adhesion as well as mechanical or optical properties.Efforts also have been devoted to introducing bio-inspired hierarchical structures for solar cells to enhance展开更多
Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom...Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom, including real spin, valley pseudospin, and layer pseudospin. For example, spin-valley coupling results in valley-dependent circular dichroism in which electrons with particular spin （up or down） can be selectively excited by chiral optical pumping in monolayer TMDs, whereas in few-layer TMDs, the interlayer hopping further affects the spin-valley coupling. In addition to valley and layer pseudospins, here we propose a new degree of freedom--stacking pseudospin--and demonstrate new phenomena correlated to this new stacking freedom that otherwise require the application of external electrical or magnetic field. We investigated all possible stacking configurations of chemical-vapor-deposition-grown trilayer MoS2 （AAA, ABB, AAB, ABA, and 3R）. Although the AAA, ABA, 3R stackings possess a sole peak with lower degree of valley polarization than that in monolayer samples, the AAB （ABB） stackings exhibit two distinct peaks, one similar to that observed in monolayer MoS2 and findings provide a more future valleytronics. an additional unpolarized complete understanding of peak at lower energy. Our valley quantum control for展开更多
The emergence of low-dimensional nanomaterials has brought revolutionized development of magnetism,as the size effect can significantly influence the spin arrangement.Since the first demonstration of truly two-dimensi...The emergence of low-dimensional nanomaterials has brought revolutionized development of magnetism,as the size effect can significantly influence the spin arrangement.Since the first demonstration of truly two-dimensional magnetic materials(2DMMs)in 2017,a wide variety of magnetic phases and associated properties have been exhibited in these 2DMMs,which offer a new opportunity to manipulate the spin-based devices efficiently in the future.Herein,we focus on the recent progress of 2DMMs and heterostructures in the aspects of their structural characteristics,physical properties,and spintronic applications.Firstly,the microscopy characterization of the spatial arrangement of spins in 2D lattices is reviewed.Afterwards,the optical probes in the light-matter-spin interactions at the 2D scale are discussed.Then,particularly,we systematically summarize the recent work on the electronic and spintronic devices of 2DMMs.In the section of electronic properties,we raise several exciting phenomena in 2DMMs,i.e.,long-distance magnon transport,field-effect transistors,varying magnetoresistance behavior,and(quantum)anomalous Hall effect.In the section of spintronic applications,we highlight spintronic devices based on 2DMMs,e.g.,spin valves,spin-orbit torque,spin field-effect transistors,spin tunneling field-effect transistors,and spin-filter magnetic tunnel junctions.At last,we also provide our perspectives on the current challenges and future expectations in this field,which may be a helpful guide for theorists and experimentalists who are exploring the optical,electronic,and spintronic properties of 2DMMs.展开更多
基金supported by Fundamental Research Funds for Central Universities of SCUT(No.D2182400)Tip-top Scientific and Technical Innovative Youth Talents of Guangdong Special Support Program(No.2016TQ03N541)+1 种基金Guangdong Natural Science Funds for Distinguished Young Scholar(No.2017B030306001)the National Natural Science Foundation of China(No.51972147)。
文摘Transition metal phosphide(TMP) based electrocatalysts possessing special crystal and electronic structures attract broad attention in the field of electrocatalysis.Immense effort is made to optimize TMP catalysts aiming to satisfy the electrochemical catalysis performance.In this work,an environmentally friendly in situ green phosphating strategy and spatial limiting effect of the RuCo precursor is employed to fabricate the ruthenium nanoclusters anchored on cobalt phosphide hollow microspheres(Ru NCs/Co_(2)P HMs).The obtained Ru NCs/Co_(2)P HMs electrocatalysts exhibit high hydrogen evolution reaction(HER) activity at wide pH ranges,which require an overpotential of 77 mV to achieve the current density of 10 mA/cm^(2) in 0.5 mol/L H_(2)SO_(4) and 118 mV in 1.0 mol/L KOH.Besides,the multifunctional Ru NCs/Co_(2)P HMs exhibit good oxygen evolution reaction(OER) activity with an overpotential of 197 mV to reach the current density of 10 mA/cm^(2) in 0.5 mol/L H_(2)SO_(4),which is below that of the commercial RuO_(2) electrocatalyst(248 mV).A two-electrode electrolyzer is assembled as well,in acid electrolyte,it achieves a current density of 10 mA/cm^(2) at a voltage of 1.53 V,which is superior to that of the benchmark of precious metal-based electrolyzer(1.58 V).
基金supported by MOE under AcRF Tier 2(ARC 19/15,No.MOE2014-T2-2-093,MOE2015T2-2-057,MOE2016-T2-2-103,MOE2017-T2-1-162)and AcRF Tier 1(2016-T1-001-147,2016-T1-002-051,2017-T1001-150,2017-T1-002-119)NTU under Start-Up Grant(M4081296.070.500000)in Singapore.
文摘Semiconductor nanomaterial-based epitaxial heterostructures with precisely controlled compositions and morphologies are of great importance for various applications in optoelectronics,thermoelectrics,and catalysis.Until now,various kinds of epitaxial heterostructures have been constructed.In this minireview,we will first introduce the synthesis of semiconductor nanomaterial-based epitaxial heterostructures by wet-chemical methods.Various architectures based on different kinds of seeds or templates are illustrated,and their growth mechanisms are discussed in detail.Then,the applications of epitaxial heterostructures in optoelectronics,catalysis,and thermoelectrics are described.Finally,we provide some challenges and personal perspectives for the future research directions of semiconductor nanomaterial-based epitaxial heterostructures.
基金supported by the National Natural Science Foundation of China(Nos.52090020,51722209,and 51525205)the National Key Research and Development Program of China(No.2018YFA0305900)+3 种基金Z.S.Z.acknowledges the NSF for Distinguished Young Scholars of Hebei Province of China(No.E2018203349)M.D.M.acknowledges the China Postdoctoral Science Foundation(No.2021M691051)Z.X.F.and H.Z.thank the support from ITC via Hong Kong Branch of National Precious Metals Material Engineering Research Center(NPMM),the Start-Up Grants(Nos.9380100,9610480,and 7200651)grants(Nos.9610478,1886921,7020013,and 7005512)from City University of Hong Kong.
文摘As one of the important materials,nanocrystalline Au(n-Au)has gained numerous interests in recent decades owing to its unique properties and promising applications.However,most of the current n-Au thin films are supported on substrates,limiting the study on their mechanical properties and applications.Therefore,it is urgently desired to develop a new strategy to prepare nAu materials with superior mechanical strength and hardness.Here,a hard n-Au material with an average grain size of~40 nm is prepared by cold-forging of the unique Au nanoribbons(NRBs)with unconventional 4H phase under high pressure.Systematic characterizations reveal the phase transformation from 4H to face-centered cubic(fcc)phase during the cold compression.Impressively,the compressive yield strength and Vickers hardness(HV)of the prepared n-Au material reach~140.2 MPa and~1.0 GPa,which are 4.2 and 2.2 times of the microcrystalline Au foil,respectively.This work demonstrates that the combination of high-pressure cold-forging and the in-situ 4H-to-fcc phase transformation can effectively inhibit the grain growth in the obtained n-Au materials,leading to the formation of novel hard n-Au materials.Our strategy opens up a new avenue for the preparation of nanocrystalline metals with superior mechanical property.
文摘Controlled synthesis of transition metal dichalcogenide (TMD) monolayers with unusual crystal phases has attracted increasing attention due to their promising applications in electrocatalysis.However,the facile and large-scale preparation of TMD monolayers with high-concentration unusual crystal phase still remains a challenge.Herein,we report the synthesis of MoX2 (X =Se or S) monolayers with high-concentration semimetallic 1T'phase by using the 4H/face-centered cubic (fcc)-Au nanorod as template to form the 4H/fcc-Au@MoX2 nanocomposite.The concentrations of 1T'phase in the prepared MoSe2 and MoS2 monolayers are up to 86% and 81%,respectively.As a proof-of-concept application,the obtained Au@MoS2 nanocomposite is used for the electrocatalytic hydrogen evolution reaction (HER) in acid medium,exhibiting excellent performance with a low overpotential of 178 mV at the current density of 10 mNcm^2,a small Tafel slope of 43.3 mV/dec,and excellent HER stability.This work paves a way for direct synthesis of TMD monolayers with high-concentration of unusual crystal phase for the electrocatalytic application.
基金supported by the Ministry of Education under AcRF Tier 2 (ARC 19/15, No. MOE2014-T2-2-093 MOE2015-T2-2-057+6 种基金 MOE2016-T2-2-103 MOE2017-T2-1-162)AcRF Tier 1 (2016-T1-001-147 2016-T1-002-051 2017-T1-001-150 2017-T1-002-119)Nanyang Technological University under StartUp Grant (M4081296.070.500000) in Singapore
文摘In the controlled synthesis of noble metal nanostructures using wet-chemical methods, normally, metal salts/complexes are used as precursors, and surfactants/ligands are used to tune/stabilize the morphology of nanostructures. Here, we develop a facile electrochemical method to directly convert Pt wires to Pt concave icosahedra and nanocubes on carbon paper through the linear sweep voltammetry in a classic three-electrode electrochemical cell. The Pt wire, carbon paper and Ag/AgCl(3 mol L-1 KCl) are used as the counter, working and reference electrodes, respectively.Impressively, the formed Pt nanostructures exhibit better electrocatalytic activity towards the hydrogen evolution compared to the commercial Pt/C catalyst. This work provides a simple and effective way for direct conversion of Pt wires into well-defined Pt nanocrystals with clean surface. We believe it can also be used for preparation of other metal nanocrystals,such as Au and Pd, from their bulk materials, which could exhibit various promising applications.
基金supported by the Joint Research Fund for Overseas Chinese, Hong Kong and Macao Scholars (51528201)the MOE under AcRF Tier 2 (ARC 19/15, MOE2014-T2-2-093, MOE2015-T22-057, MOE2016-T2-2-103, MOE2017-T2-1-162)+1 种基金AcRF Tier 1 (2016-T1001-147, 2016-T1-002-051, 2017-T1-001-150, 2017-T1-002-119)NTU under Start-Up Grant (M4081296.070.500000) in Singapore
文摘It is the nature of crystals to exist in different polymorphs. The recent emergence of two-dimensional(2 D) materials has evoked the discovery of a number of new crystal phases that are different from their bulk structures at ambient conditions, and revealed novel structure-dependent properties, which deserve in-depth understanding and further exploration. In this contribution, we review the recent development of crystal phase control in 2 D materials, including group V and VI. transition metal dichalcogenides(TMDs), group IVA metal chalcogenides and noble metals. For each group of materials, we begin with introducing the various existing crystal phases and their structure-related properties, followed by a detailed discussion on factors that influence these crystal structures and thus the possible strategies for phase control. Finally, after summarizing the whole paper, we present the challenges and opportunities in this research direction.
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the financial supports from the National Natural Science Foundation of China(21902062 and 21705056)the Natural Science Foundation of Shandong Province(ZR2019YQ10 and ZR2018PB009)+1 种基金the Young Taishan Scholars Program(tsqn201812080)the Open Funds of the State Key Laboratory of Electroanalytical Chemistry(SKLEAC201901)。
文摘Developing electrocatalysts with high performance and low cost for the oxygen evolution reaction(OER)is of great importance for fabricating renewable energy storage and conversion devices.Here,a series of boron-doped graphene(BG)-supported bimetallic oxides of Co and Ni were obtained and served as OER electrocatalysts.Surprisingly,the annealed Co-Ni-Ox/BG with a Co/Ni ratio of 1:1 exhibits high performance toward oxygen evolution in alkaline electrolyte.The overpotential is only 310 mV at the current density of 10 mA cm-2,superior to many mono-metallic oxides reported before,and even comparable to the commercial RuO2.The regulation of charge distribution in bimetallic oxides and the strong synergistic coupling effects together contribute to the superior electrocatalytic performance of the Co-Ni-Ox/BG toward OER.This study also offers several effective ways to design high-performance OER electrocatalysts for water splitting.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.61904077,61801210,91833302,11574080,61904080)the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20180686,BK20190670,BK20161008)+2 种基金the funding for“Distinguished professors”and“High-level talents in six industries”of Jiangsu Province(Grant No.XYDXX-021)the Fundamental Research Funds for the Central Universitiesthe start-up foundation of Nanjing Tech University and Northwestern Polytechnical University.
文摘Mid-infrared(MIR)light-emitting devices play a key role in optical communications,thermal imaging,and material analysis applications.Two-dimensional(2D)materials offer a promising direction for next-generation MIR devices owing to their exotic optical properties,as well as the ultimate thickness limit.More importantly,van der Waals heterostructures-combining the best of various 2D materials at an artificial atomic level-provide many new possibilities for constructing MIR light-emitting devices of large tuneability and high integration.Here,we introduce a simple but novel van der Waals heterostructure for MIR light-emission applications built from thin-film BP and transition metal dichalcogenides(TMDCs),in which BP acts as an MIR light-emission layer.For BP–WSe_(2) heterostructures,an enhancement of~200% in the photoluminescence intensities in the MIR region is observed,demonstrating highly efficient energy transfer in this heterostructure with type-Ⅰ band alignment.For BP-MoS_(2) heterostructures,a room temperature MIR light-emitting diode(LED)is enabled through the formation of a vertical PN heterojunction at the interface.Our work reveals that the BP-TMDC heterostructure with efficient light emission in the MIR range,either optically or electrically activated,provides a promising platform for infrared light property studies and applications.
基金X.C.and Z.Z.contributed equally to this work.This work was supported financially by MOE under AcRF Tier 2(grant nos.MOE2015-T2-2-057,MOE2016-T2-2-103,and MOE2017-T2-1-162)AcRF Tier 1(grant nos.2016-T1-002-051,2017-T1-001-150,and 2017-T1-002-119)+4 种基金NTU under Start-Up Grant(no.M4081296.070.500000)Agency for Science,Technology and Research(A*STAR)under its AME IRG(Project No.A1783c0009)in Singapore.L.G.acknowledges the Key Research Program of Frontier Sciences,CAS(grant no.QYZDB-SSW-JSC035)National Natural Science Foundation of China(grant nos.51672307 and 51421002)We are thankful to the Facility for Analysis,Characterization,Testing and Simulation,Nanyang Technological University,Singapore,for the use of their electron microscopy(and/or X-ray)facilities.We would also like to thank 1W1B beamline of Beijing Synchrotron Radiation Facility(BSRF)for supporting this project.H.Z.thanks the support from ITC via the Hong Kong Branch of National Precious Metals Material Engineering Research Center and the Start-Up Grant from the City University of Hong Kong.This study used resources of the Advanced Photon Source,an Office of the Science User Facility,operated by the U.S.Department of Energy(DOE)Office of Science by Argonne National Laboratory and was supported by the U.S.DOE under contract no.DE-AC02-06CH11357the Canadian Light Source and its funding partners.This research also used 7-BM of the National Synchrotron Light Source II,U.S.DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no.DE-SC0012704.
文摘The rational design and synthesis of multimetallic nanostructures(NSs)with rich defects are of significant importance for their diverse applications,including their promising usage as high-efficiency catalysts for alcohol oxidation reaction as a fuel source.Here,we report the synthesis of defect-rich,candied haws-shaped AuPtNi NSs using presynthesized gold(Au)nanowires as templates.The ternary AuPtNi NSs possess rich defects such as twins,stacking faults,and atomic steps.Impressively,the AuPtNi NSs exhibited excellent mass and specific activities toward methanol and ethanol oxidation reactions under acidic conditions.Our current work paves the way for the rational design and controlled synthesis of defect-rich multimetallic NSs to boost their performances in catalytic reactions.
基金supported by Ministry of Education(Singapore)under AcRF Tier 2(ARC 19/15,MOE2014-T2-2-093,MOE2015-T2-2-057 and MOE2016-T2-2-103)and AcRF Tier 1(2016T1-001-147 and 2016-T1-002-051)NTU under Start-Up Grant(M4081296.070.500000)+2 种基金NOL Fellowship Programme Research Grant in Singaporesupported by the Singapore National Research Foundation under its Environmental&Water Technologies Strategic Research Programme and administered by the Environment&Water Industry Programme Office(EWI)of the PUB(project No.:1301-IRIS-47)supported by the National Research Foundation,Prime Minister’s Office,Singapore under its Campus for Research Excellence and Technological Enterprise(CREATE)programme
文摘The increasing demand of clean water and ef- fective way to recycle industrial wastewater has offered a new application for carbon-based three-dimensional （3D） porous networks as sorbents due to their superior sorption abilities. Through the surface modification and hybridization with functional materials, the physical and chemical properties of the 3D carbon-based materials can be engineered. In this work, graphene-MoS2 aerogels （GMAs） with bulky shape are synthesized via a one-pot hydrothermal method. The obtained GMAs show quick sorption rate and high sorption capacity towards a wide variety of contaminants. The sorption covers not only organic solvents or organic dyes, but also toxic heavy metals ions such as Hg2＋ and Pb2＋. More importantly, the sorption capacity towards metal ions can be optimized by simply changing the loading amount of MoS2.
基金This work was supported by MOE under AcRF Tier 2(ARC 19/15,Nos.MOE2014-T2-2-093,MOE2015-T2-2-057,MOE2016-T2-2-103,and MOE2017-T2-1-162)AcRF Tier 1(2016-T1-001-147,2016-T1-002-051,2017-T1-001-150,and 2017-T1-002-119)+2 种基金Nanyang Technological University under the Start-Up Grant(M4081296.070.500000)in SingaporeS.H.thanks the support from the Fundamental Research Funds for the Central Universities(No.PA2018GDQT0013)in ChinaWe would like to acknowledge the Facility for Analysis,Characterization,Testing and Simulation,Nanyang Technological University,Singapore,for use of their electron microscopy(and/or X-ray)facilities.H.Z.thanks the support from the Innovation and Technology Commission via the Hong Kong Branch of National Precious Metals Material Engineering Research Center and the Start-Up Grant from the City University of Hong Kong.
文摘The layered transition metal dichalcogenides(TMDs)and transition metal phosphides are low-cost,earth-abundant,and robust electrocatalysts for hydrogen evolution reaction(HER).Integrating them into hybrid nanostructures is potentially promising to further boost the catalytic activity toward HER based on their synergistic effects.Herein,we report a general method for the synthesis of a series of MoSe_(2)-based hybrid nanostructures,including MoSe_(2)-Ni_(2)P,MoSe_(2)-Co_(2)P,MoSe_(2)-Ni,MoSe_(2)-Co,and MoSe_(2)-NiS,by postgrowth of Ni_(2)P,Co_(2)P,Ni,Co,and NiS nanostructures on the presynthesized MoSe_(2) nanosheet-assembled nanospheres,respectively,via a colloidal synthesis method.As a proof-of-concept application,the as-synthesized hybrid nanostructures are used as electrocatalysts for HER,exhibiting high activity and stability in acidic media.Among them,the MoSe_(2)-Co_(2)P composite shows the highest HER activity with an overpotential of 167 mV at 10 mA cm^(-2).
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.
基金MOE2016-T2-1-131(Tier 2)Singapore was acknow-ledged.the National Natural Science Foundation of China (Nos.11274380,91433103, 11622437,and 61674171)the Fundamental Research Funds for the Central Universities,China and the Research Funds of Renmin University of China (No.16XNLQ01)Calculations were performed at the pkysics lab of high-performance computing of Renmin University of China.
基金supported by the National Natural Science Foundation of China(Grant Nos.51572057,51902069,GZ213054,21571101)the Natural Science Foundation of Jiangsu Province(Grant No.BK20161543)the support from the Start-up Grant(Grant Nos.7200656,9610482)from City University of Hong Kong。
文摘Lateral hetero-junctions are considered as potential candidate for building blocks in modern electronics and optoelectronics,however,the construction of which remains a challenge.In this work,by using a laser-assisted manufacture technique,WSe2/WO3-x hetero-junction and monolayer/trilayer WSe2 homo-junction with Schottky diode like behavior are fabricated,both of which present competitive performance for photodetection and power generation in a wide range of wavelengths from ultraviolet to infrared,with maximum photoresponsivity of 10 A/W,external quantum efficiency of 14%,and power conversion efficiency of 1.3%.Combined with Kelvin probe microscopy and electrical transport measurements,it is demonstrated that the barrier-induced built-in electric field at WSe2/WO3-x interface,and the energy band discontinuities at the monolayer/trilayer WSe2 interface facilitate the separation of photo-generated electron-hole pairs.Our work provides a solid step towards the controllable construction of lateral junctions by laser-assisted manufacture for exploiting van der Waals materials-based novel electronic and optoelectronic applications.
基金This work was supported by the National Key R&D Program(No.2017YFA0204503)the National Natural Science Foundation of China(Nos.22071172,91833306,21875158,51633006,and 51733004)+1 种基金Z.F.thanks the funding support from ITC via Hong Kong Branch of National Precious Metals Material Engineering Research Center(NPMM),and the Start-Up Grants(Nos.9610480 and 7200651)Grant from City University of Hong Kong(No.7005512).
文摘Electrochemical CO_(2) reduction reaction(CO_(2)RR)is an attractive pathway for closing the anthropogenic carbon cycle and storing intermittent renewable energy by converting CO_(2) to valuable chemicals and fuels.The production of highly reduced carbon compounds beyond CO and formate,such as hydrocarbon and oxygenate products with higher energy density,is particularly desirable for practical applications.However,the productivity towards highly reduced chemicals is typically limited by high overpotential and poor selectivity due to the multiple electron-proton transfer steps.Tandem catalysis,which is extensively utilized by nature for producing biological macromolecules with multiple enzymes via coupled reaction steps,represents a promising strategy for enhancing the CO_(2)RR performance.Improving the efficiency of CO_(2)RR via tandem catalysis has recently emerged as an exciting research frontier and achieved significant advances.Here we describe the general principles and also considerations for designing tandem catalysis for CO_(2)RR.Recent advances in constructing tandem catalysts,mainly including bimetallic alloy nanostructures,bimetallic heterostructures,bimetallic core-shell nanostructures,bimetallic mixture catalysts,metal-metal organic framework(MOF)and metal-metallic complexes,metal-nonmetal hybrid nanomaterials and copper-free hybrid nanomaterials for boosting the CO_(2)RR performance are systematically summarized.The study of tandem catalysis for CO_(2)RR is still at the early stage,and future research challenges and opportunities are also discussed.
基金the National Natural Science Foundation of China(91963113)。
文摘The rational design and synthesis of hybrid-type electrode nanomaterials are significant for their diverse applications,including their potential usage as high-efficiency nanoarchitectures for supercapacitors(SCs)as a class of promising energy-storage systems for powering next-generation electric vehicles and electronic devices.Here,we reported a facile and controllable synthesis of core-shell Ni_(3)S_(2)@NiWO_(4)nanoarrays to fabricate a freestanding electrode for hybrid SCs.Impressively,the as-prepared freestanding Ni_(3)S_(2)@NiWO_(4)electrode presents an ultrahigh areal capacity of 2032μA h cm^(-2)at 5 mA cm^(-2),and a capacity retention of 63.6%even when the current density increased up to 50 mA cm^(-2).Remarkably,the Ni_(3)S_(2)@NiWO_(4)nanoarraybased hybrid SC delivers a maximum energy density of 1.283 mW h cm^(-2)at 3.128 mW cm^(-2)and a maximum power density of 41.105 mW cm^(-2)at 0.753 mW h cm^(-2).Furthermore,the hybrid SC exhibits a capacity retention of 89.6%even after continuous 10,000 cycles,proving its superior stability.This study provides a facile pathway to rationally design a variety of core-shell metal nanostructures for high-performance energy storage devices.
文摘Hierarchical structures with different length scales,which appear in many animals and plants,play important roles in their structural and functional integrity[1,2].These structures endow their host animals and plants with intriguing properties including super-hydrophobicity,reversible adhesion as well as mechanical or optical properties.Efforts also have been devoted to introducing bio-inspired hierarchical structures for solar cells to enhance
文摘Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom, including real spin, valley pseudospin, and layer pseudospin. For example, spin-valley coupling results in valley-dependent circular dichroism in which electrons with particular spin （up or down） can be selectively excited by chiral optical pumping in monolayer TMDs, whereas in few-layer TMDs, the interlayer hopping further affects the spin-valley coupling. In addition to valley and layer pseudospins, here we propose a new degree of freedom--stacking pseudospin--and demonstrate new phenomena correlated to this new stacking freedom that otherwise require the application of external electrical or magnetic field. We investigated all possible stacking configurations of chemical-vapor-deposition-grown trilayer MoS2 （AAA, ABB, AAB, ABA, and 3R）. Although the AAA, ABA, 3R stackings possess a sole peak with lower degree of valley polarization than that in monolayer samples, the AAB （ABB） stackings exhibit two distinct peaks, one similar to that observed in monolayer MoS2 and findings provide a more future valleytronics. an additional unpolarized complete understanding of peak at lower energy. Our valley quantum control for
基金This work was supported by the National Key Research and Development Program of China(Grant No.2017YFE0131900)the Major Program of National Natural Science Foundation of China(Grant No.91833306)+1 种基金the National Natural Science Foundation of China(Grant No.61801210,91833302,61904077,and 61904080)the Natural Science Foundation of Jiangsu Province(Grant No.BK20180686,BK20161008,and BK20190670).
文摘The emergence of low-dimensional nanomaterials has brought revolutionized development of magnetism,as the size effect can significantly influence the spin arrangement.Since the first demonstration of truly two-dimensional magnetic materials(2DMMs)in 2017,a wide variety of magnetic phases and associated properties have been exhibited in these 2DMMs,which offer a new opportunity to manipulate the spin-based devices efficiently in the future.Herein,we focus on the recent progress of 2DMMs and heterostructures in the aspects of their structural characteristics,physical properties,and spintronic applications.Firstly,the microscopy characterization of the spatial arrangement of spins in 2D lattices is reviewed.Afterwards,the optical probes in the light-matter-spin interactions at the 2D scale are discussed.Then,particularly,we systematically summarize the recent work on the electronic and spintronic devices of 2DMMs.In the section of electronic properties,we raise several exciting phenomena in 2DMMs,i.e.,long-distance magnon transport,field-effect transistors,varying magnetoresistance behavior,and(quantum)anomalous Hall effect.In the section of spintronic applications,we highlight spintronic devices based on 2DMMs,e.g.,spin valves,spin-orbit torque,spin field-effect transistors,spin tunneling field-effect transistors,and spin-filter magnetic tunnel junctions.At last,we also provide our perspectives on the current challenges and future expectations in this field,which may be a helpful guide for theorists and experimentalists who are exploring the optical,electronic,and spintronic properties of 2DMMs.
