The single crystal bismuth nanowire arrays grown along [0112] with the diameter of 30 nm was synthesized in the pore of anodic aluminum oxide templates through electrodeposi- tion process. The temperature dependent el...The single crystal bismuth nanowire arrays grown along [0112] with the diameter of 30 nm was synthesized in the pore of anodic aluminum oxide templates through electrodeposi- tion process. The temperature dependent electric conductance of Bi nanowire arrays was measured from 78 K to 320 K. We found that the semimetal-to-semiconductor transition happened around 230 K for 30 nm Bi nanowires oriented along [0112] and the electric con- ductance of the nanowires had a strong temperature dependence.展开更多
Large-scale GaN nanowires are successfully synthesized by ammoniating Ga2O3 films on Nb layer deposited on Si(111)substrates at 850℃.X-ray diffraction(XRD),scanning electron microscopy(SEM),field-emssion transmission...Large-scale GaN nanowires are successfully synthesized by ammoniating Ga2O3 films on Nb layer deposited on Si(111)substrates at 850℃.X-ray diffraction(XRD),scanning electron microscopy(SEM),field-emssion transmission electron microscope(FETEM),Fourier transformed infrared spectrum(FTIR)are used to characterize the structural and morphological properties of the as-synthesized GaN nanowires.The results reveal that the nanowires are pure hexagonal GaN wurtzite structure with a length of about several microns and a diameter between 50nm and 100nm.Finally,discussed briefly is the formation mechanism of gallium nitride nanowires.展开更多
In this paper, cable-like PEDOT/PSS-ZnO nanowires are successfully fabricated under vacuum condi- tion by self-assembly of the PEDOT/PSS-ZnO composite initially prepared via sol-gel method. Characterized by TEM and ED...In this paper, cable-like PEDOT/PSS-ZnO nanowires are successfully fabricated under vacuum condi- tion by self-assembly of the PEDOT/PSS-ZnO composite initially prepared via sol-gel method. Characterized by TEM and EDX, the nanowire is found to have a polycrystalline ZnO inner core that is sheathed by the PEDOT/PSS blends and the nanowire has an outer diameter of ca. 100 nm. The results also indicate that the morphology of PEDOT/PSS- ZnO nanocomposite is greatly influenced by external vac- uum condition and aging time. The feasible and simple ap- proach that we have developed provides a new strategy for the synthesis of novel one-dimensional nanocomposites.展开更多
A comprehensive review on interfacial reactions to form silicides between metal and Si nanowire or wafer is given.Formation of silicide contacts on Si wafers or Si nanowires is a building block needed in making curren...A comprehensive review on interfacial reactions to form silicides between metal and Si nanowire or wafer is given.Formation of silicide contacts on Si wafers or Si nanowires is a building block needed in making current-based Si devices.Thus,the microstructure control of silicide formation on the basis of kinetics of nucleation and growth has relevant applications in microelectronic technology.Repeating events of homogeneous nucleation of epitaxial silicides of Ni and Co on Si in atomic layer reaction is presented.The chemical effort on intrinsic diffusivities in diffusion-controlled layer-typed intermetallic compound growth of Ni2Si is analyzed.展开更多
Less-expensive but efficient electrocatalysts are essential to accelerate the commercialization of fuel cells.Herein,ultrathin PdPb nanowires(PdPb NWs)with a diameter of around 3.5 nm were prepared by using a one-step...Less-expensive but efficient electrocatalysts are essential to accelerate the commercialization of fuel cells.Herein,ultrathin PdPb nanowires(PdPb NWs)with a diameter of around 3.5 nm were prepared by using a one-step hydrothermal method.The introduction of Pb in Pd-based bimetallic nanostructures produced high differences in the morphology from Pd nanoparticles(NPs)to various PdPb NWs.All the as-prepared PdPb NWs exhibited better electrocatalytic activity and durability than Pd NPs due to the synergistic effect.Especially,Pd65Pb35 possessed the highest current density of about 3460 mA mgPd^−1 for the ethanol electrooxidation which was around 6.3 times higher than commercial Pd/C.The high-performance of Pd65Pb35 is attributed to the defect-rich and stable nanowire structure with optimized surface atomic arrangement,as evidenced by high resolution transmission electron microscopy measurements and long-time treatment in an acidic media.The differences in the morphologies and electrocatalytic activities of PdPb NWs with varied Pb contents have also been discussed and analyzed.展开更多
As the necessary components for various modern electronic and optoelectronic devices, novel transparent electrodes(TEs) with the low cost, abundance features, and comparable performance of indium tin oxide(ITO) are in...As the necessary components for various modern electronic and optoelectronic devices, novel transparent electrodes(TEs) with the low cost, abundance features, and comparable performance of indium tin oxide(ITO) are inquired materials. Metal nanowires(NWs) with the excellent photoelectric properties as next-generation TE candidates have widely applications in smart optoelectronic devices such as electronic skins, wearable electronics, robotic skins, flexible and stretchable displays. This review describes the synthetic strategies for the preparation of metal NWs, the assemble process for metal NW films,and the practical aspects of metal NW films with the desired properties in various low-cost, flexible,and solution-based photoelectric devices.展开更多
Integration of molybdenum disulfide （MoS2） onto high surface area photocathod is highly desired to minimize the overpotential for the solar-powered hydrogen evolution reaction （HER）. Semiconductor nanowires （NWs...Integration of molybdenum disulfide （MoS2） onto high surface area photocathod is highly desired to minimize the overpotential for the solar-powered hydrogen evolution reaction （HER）. Semiconductor nanowires （NWs） are beneficial use in photoelectrochemistry because of their large electrochemically availab surface area and inherent ability to decouple light absorption and the transpo of minority carriers. Here, silicon （Si） NW arrays were employed as a mod photocathode system for MoS2 wrapping, and their solar-driven HER activil was evaluated. The photocathode is made up of a well-defined MoSJTiO2/Si coaxial NW heterostructure, which yielded photocurrent density up to 15 mA/cm2 （at 0 V vs. the reversible hydrogen electrode （RHE）） with goo stability under the operating conditions employed. This work reveals the earth-abundant electrocatalysts coupled with high surface area NW electrod~ can provide performance comparable to noble metal catalysts for photocathod hydrogen evolution.展开更多
Conductive and adhesive hydrogels are promising materials for designing bioelectronics.To satisfy the high conductivity of bioelectronic devices,metal nanomaterials have been used to fabricate composite hydrogels.Howe...Conductive and adhesive hydrogels are promising materials for designing bioelectronics.To satisfy the high conductivity of bioelectronic devices,metal nanomaterials have been used to fabricate composite hydrogels.However,the fabrication of a conductive-nanomaterial-incorporated hydrogel with high performance is a great challenge because of the easy aggregation nature of conductive nanomaterials making processing difficult.Here,we report a kind of adhesive aero-hydrogel hybrid conductor(AAHC)with stretchable,adhesive and anti-bacteria properties by in situ formation of a hydrogel network in the aerogel-silver nanowires(AgNWs)assembly.The AgNWs with good conductivity are wellintegrated on the inner-surface of shape-memory chitosan aerogel,which created a conductive framework to allow hydrogel back-filling.Reinforcement by the aerogel-silver makes the hybrid hydrogel tough and stretchable.Functional groups from the hydrogel allow strong adhesion to wet tissues through molecular stitches.The inherent bacteria-killing ability of silver ions endows the conductive hydrogel with excellent anti-bacteria performance.The proposed facile strategy of aerogel-assisted assembly of metal nanomaterials with hydrogel opens a new route to incorporate functional nanoscale building blocks into hydrogels.展开更多
Free-standing metallic nanostructures are considered to be highly relevant to many branches of science and technology with applications of three dimensional metallic nanostructures ranging from optical reflectors,actu...Free-standing metallic nanostructures are considered to be highly relevant to many branches of science and technology with applications of three dimensional metallic nanostructures ranging from optical reflectors,actuators,and antenna,to free-standing electrodes,mechanical,optical,and electrical resonators and sensors.Strain-induced out-of-plane fabrication has emerged as an effective method which uses relaxation of strain-mismatched materials.In this work,we report a study of the thermal annealing-induced shape modification of free-standing nanostructures,which was achieved by introducing compositional or microstructural nonuniformity to the nanowires.In particular gradient,segmented and striped hetero-nanowires were grown by focused-ion-beam-induced chemical vapor deposition,followed by rapid thermal annealing in a N2 atmosphere.Various free-standing nanostructures were produced as a result of the crystalline/grain growth and stress relief.展开更多
An easy and effective solution based procedure for the synthesis of noble metal （both Au and Ag） tipped semiconductor nanomaterials is demonstrated where the metal precursors are taken in water and the semiconductor...An easy and effective solution based procedure for the synthesis of noble metal （both Au and Ag） tipped semiconductor nanomaterials is demonstrated where the metal precursors are taken in water and the semiconductors in organic medium, exploiting the phase transfer and reducing capability of suitably chosen ligands. The phase tranfer route is a generalised approach to form either Ag or Au tips on cadmium chalcogenide nanoparticles and nanorods. While multiple dots of noble metals are formed on the semiconductor nanomaterials initiall~ these coalesce into larger islands with time. The hybrids are characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, photoluminescence （PL）, ultraviolet-visible spectroscopy （UV-vis） and X-ray photoelectron spectroscopy （XPS）. A detailed FTIR analysis was also carried out to delineate the role of the ligands in the synthesis.展开更多
The atomic structure of quasi one-dimensional(1D) van der Waals materials can be regarded as the stacking of atomic chains to form thin flakes or nanoribbons, which substantially differentiates them from typical two-d...The atomic structure of quasi one-dimensional(1D) van der Waals materials can be regarded as the stacking of atomic chains to form thin flakes or nanoribbons, which substantially differentiates them from typical two-dimensional(2D) layered materials and 1D nanotube/nanowire array. Here we present our studies on quasi 1D gold selenide(AuSe) that possesses highly anisotropic crystal structure, excellent electrical conductivity, giant magnetoresistance, and unusual reentrant metallic behavior. The low inplane symmetry of AuSe gives rise to its high anisotropy of vibrational behavior. In contrast, quasi 1D AuSe exhibits high in-plane electrical conductivity along the directions of both atomic chains and perpendicular one, which can be understood as a result of strong interchain interaction. We found that AuSe exhibits a near quadratic nonsaturating giant magnetoresistance of 1841% with the magnetic field perpendicular to its in-plane. We also observe unusual reentrant metallic behavior, which is caused by the carrier mismatch in the multiband transport. Our works help to establish fundamental understandings on quasi 1D van der Waals semimetallic AuSe and identify it as a new candidate for exploring giant magnetoresistance and compensated semimetals.展开更多
In this work,we prepared silicon nanowires(Si NWs) on both fluorine-doped SnO 2(FTO) coated glass substrate and common glass substrate by catalytic thermal chemical vapor deposition(CVD) using indium film as the catal...In this work,we prepared silicon nanowires(Si NWs) on both fluorine-doped SnO 2(FTO) coated glass substrate and common glass substrate by catalytic thermal chemical vapor deposition(CVD) using indium film as the catalyst.It is confirmed that indium can catalyze the growth of Si NWs.More importantly,we found that tin generated in situ from the reduction of SnO 2 by indium can act as catalyst,which greatly enhances the growth of Si NWs on FTO substrate.The obtained Si NWs have a uniform crystalline-amorphous core-shell structure that is formed via vapor-liquid-solid and vapor-solid growth of silicon sequentially.This work provides a strategy to prepare Si NWs in high yield by catalytic thermal CVD using the low melting point metal catalysts.展开更多
Optical near-field excitations were investigated on the basis of molecular alignment control of liquid crystals (LCs) on an optically rewritable nanostructure of photoreactive molecular thin films. Twisted nematic (TN...Optical near-field excitations were investigated on the basis of molecular alignment control of liquid crystals (LCs) on an optically rewritable nanostructure of photoreactive molecular thin films. Twisted nematic (TN) cells of LC molecules were constructed utilizing ITO substrates with 260 nm gratings of an azobenzene molecular thin film, fabricated using standing evanescent waves. The polarization changes of light transmitted through the TN cells, which were due to the alignment changes of LC molecules locally rubbed by the azobenzene nanogratings, were observed. Furthermore, we demonstrated local plasmon excitation of Au nanowires deposited on the azobenzene nanogratings using oblique vacuum evaporation, a phenomenon that produced strong anti-optical absorption spectra. The modulation of the local plasmon resonance in metallic nanowires decorated with LC molecules was confirmed.展开更多
Metallic nanowire arrays （NWAs） possess wide application prospects due to their unique property, and the tailoring of NWAs＇ structure and morphology is of importance since it would significantly influence the per- ...Metallic nanowire arrays （NWAs） possess wide application prospects due to their unique property, and the tailoring of NWAs＇ structure and morphology is of importance since it would significantly influence the per- formance of NWAs. In the present work, the morphology and structure evolution of the NWAs prepared by the newly developed die nanoimprinting technique has been investigated in detail. It was found that increasing pro- cessing temperature, time and pressure could increase the length of the nanowires and change the NWAs＇ morphol- ogy from monodispersed form to aggregated form. Increasing processing time and temperature within the supercooled liquid region would promote crystallization, while increasing processing pressure could suppress the crystallization. This work provided important insights into the structure and morphology evolution, and therefore, the tailoring of metallic NWAs prepared by die nanoimprinting through adjusting the process parameters.展开更多
Strain engineering is a powerful tool to tailor the physical properties of materials coherently stacked in an epitaxial heterostructure. Such an approach, applied to the mature field of planar heteroepitaxy, has yield...Strain engineering is a powerful tool to tailor the physical properties of materials coherently stacked in an epitaxial heterostructure. Such an approach, applied to the mature field of planar heteroepitaxy, has yielded a variety of new phenomena and devices. Recently, heteroepitaxial vertically aligned nanocomposites have emerged as alternatives to planar structures. Owing to the peculiar geometry of such nanoarchitectures, efficient strain control can be achieved, opening the way to novel functionalities. In this paper, we report a very large tensile axial strain in epitaxial transition metal nanowires embedded in an oxide matrix. We show that axial strains in excess of 1.5% can be sustained over a large thickness （a few hundred nanometers） in epitaxial nanowires having ultrasmall diameters （-3-6 nm）. The axial strain depends on the diameter of the nanowires, reflecting its epitaxial nature and the balance of interface and elastic energies. Furthermore, it is experimentally shown that such strain is metastable, in agreement with the calculations performed in the framework of the Frenkel-Kontorova model. The diameter dependence and metastability provide effective ways to control the strain, an appealing feature for the design of functional nanoarchitectures.展开更多
We have recently demonstrated that GaAs nanosheets can be grown by metal-organic chemical vapor deposition （MOCVD）. Here, we investigate these nanosheets by secondary electron scanning electron microscopy （SE-SEM）...We have recently demonstrated that GaAs nanosheets can be grown by metal-organic chemical vapor deposition （MOCVD）. Here, we investigate these nanosheets by secondary electron scanning electron microscopy （SE-SEM） and electron beam induced current （EBIC） imaging. An abrupt boundary is observed between an initial growth region and an overgrowth region in the nanosheets. The SE-SEM contrast between these two regions is attributed to the inversion of doping at the boundary. EBIC mapping reveals a p-n junction formed along the boundary between these two regions. Rectifying I-V behavior is observed across the boundary further indicating the formation of a p-n junction. The electron concentration （ND） of the initial growth region is around 1 × 10^18 cm^-3, as determined by both Hall effect measurements and low temperature photoluminescence （PL） spectroscopy. Based on the EBIC data, the minority carrier diffusion length of the nanosheets is 177 nm, which is substantially longer than the corresponding length in unpassivated GaAs nanowires measured previously.展开更多
In this study, the electrochemical behavior of monocrystalline bare Si and Ag-coated Si in hydrofluoric acid （HF） solutions with and without hydrogen peroxide （H202） was systematically tested with an electrochemic...In this study, the electrochemical behavior of monocrystalline bare Si and Ag-coated Si in hydrofluoric acid （HF） solutions with and without hydrogen peroxide （H202） was systematically tested with an electrochemical technique. By analyzing the po- larization curves, the corrosion processes were quantified and the etchants which govern the formation of silicon nanowires （SiNWs） were determined. It was discovered that both H202 and Ag enhanced the reduction reactions, irrespective of the con- ductivity type and doping concentration of Si. It is believed that the formation of SiNWs via Metal-Catalyzed Electroless Etching is a process controlled by cathodic reduction reactions.展开更多
Porous metal architectures are widely adopted as three-dimensional conducting scaffolds for constructing Li metal composite anodes,whereas their macropores hinder their practical application due to limited surface are...Porous metal architectures are widely adopted as three-dimensional conducting scaffolds for constructing Li metal composite anodes,whereas their macropores hinder their practical application due to limited surface area and large pore size of few hundred micrometers.In this work,a network of Li_(x)Cu solid solution alloy nanowires is in situ formed via infiltrating molten Li-Cu alloy into Ni foam and subsequent cooling treatment,whereby a three-component composite anode consisting of Li metal,Li_(x)Cu alloy,and Ni foam is fabricated.The Li_(x)Cu nanowires nested as secondary frame split the macropores into micropores,enlarging the active surface area and inducing uniform Li deposition significantly.The lithiophilicity of the alloy wires and the shrunken void size built by the hierarchical architecture can further tune the nucleation and growth behavior of Li.The multiscale synergetic effect between the primary and secondary scaffold guarantees the composite anode sheet with extraordinarily long-term cycling stability even under high current rates.展开更多
The oxidation of carbon monoxide is widely investigated for realistic and potential uses in energy production and environmental processes.As a probe reaction to the surface properties,it gives an insight into the rela...The oxidation of carbon monoxide is widely investigated for realistic and potential uses in energy production and environmental processes.As a probe reaction to the surface properties,it gives an insight into the relationship between the structure of active phase and catalytic performance.Noble metals alloyed with certain transition metals in the form of a nanoalloy exhibit enhanced catalytic activity for various reactions,especially when simultaneous activation of oxygen and CO is involved.This article highlights some of these insights into nanoalloy catalysts in which platinum group metal(PGM)is alloyed with a second and/or third transition metal(M/M′=Co,Fe,V,Ni,Ir,etc.),for catalytic oxidation of carbon monoxide in a gas phase.Recent studies have provided important insights into how the atomic-scale structures of the nanoalloy catalysts operate synergistically in activating oxygen and maneuvering surface oxygenated species.The exploration of atomic-scale chemical/structural ordering and coordination in correlation with the catalytic oxidation properties based on findings from ex-and in-situ synchrotron X-ray techniques is emphasized;for example,high-energy X-ray diffraction coupled to atomic-pair distribution function and X-ray absorption fine-structure spectroscopic analysis.The understanding of the detailed active sites of the nanoalloys has significant implications for the design of low-cost,active,and durable catalysts for sustainable energy production and environmental processes.展开更多
文摘The single crystal bismuth nanowire arrays grown along [0112] with the diameter of 30 nm was synthesized in the pore of anodic aluminum oxide templates through electrodeposi- tion process. The temperature dependent electric conductance of Bi nanowire arrays was measured from 78 K to 320 K. We found that the semimetal-to-semiconductor transition happened around 230 K for 30 nm Bi nanowires oriented along [0112] and the electric con- ductance of the nanowires had a strong temperature dependence.
基金National Natural Science Foundation of China(90301002,90201025)
文摘Large-scale GaN nanowires are successfully synthesized by ammoniating Ga2O3 films on Nb layer deposited on Si(111)substrates at 850℃.X-ray diffraction(XRD),scanning electron microscopy(SEM),field-emssion transmission electron microscope(FETEM),Fourier transformed infrared spectrum(FTIR)are used to characterize the structural and morphological properties of the as-synthesized GaN nanowires.The results reveal that the nanowires are pure hexagonal GaN wurtzite structure with a length of about several microns and a diameter between 50nm and 100nm.Finally,discussed briefly is the formation mechanism of gallium nitride nanowires.
文摘In this paper, cable-like PEDOT/PSS-ZnO nanowires are successfully fabricated under vacuum condi- tion by self-assembly of the PEDOT/PSS-ZnO composite initially prepared via sol-gel method. Characterized by TEM and EDX, the nanowire is found to have a polycrystalline ZnO inner core that is sheathed by the PEDOT/PSS blends and the nanowire has an outer diameter of ca. 100 nm. The results also indicate that the morphology of PEDOT/PSS- ZnO nanocomposite is greatly influenced by external vac- uum condition and aging time. The feasible and simple ap- proach that we have developed provides a new strategy for the synthesis of novel one-dimensional nanocomposites.
文摘A comprehensive review on interfacial reactions to form silicides between metal and Si nanowire or wafer is given.Formation of silicide contacts on Si wafers or Si nanowires is a building block needed in making current-based Si devices.Thus,the microstructure control of silicide formation on the basis of kinetics of nucleation and growth has relevant applications in microelectronic technology.Repeating events of homogeneous nucleation of epitaxial silicides of Ni and Co on Si in atomic layer reaction is presented.The chemical effort on intrinsic diffusivities in diffusion-controlled layer-typed intermetallic compound growth of Ni2Si is analyzed.
基金This work was financially supported by the National Natural Science Foundation of China(21773133)Taishan Scholars Advantageous and Distinctive Discipline Program for supporting the research team of energy storage materials of Shandong Province,China.
文摘Less-expensive but efficient electrocatalysts are essential to accelerate the commercialization of fuel cells.Herein,ultrathin PdPb nanowires(PdPb NWs)with a diameter of around 3.5 nm were prepared by using a one-step hydrothermal method.The introduction of Pb in Pd-based bimetallic nanostructures produced high differences in the morphology from Pd nanoparticles(NPs)to various PdPb NWs.All the as-prepared PdPb NWs exhibited better electrocatalytic activity and durability than Pd NPs due to the synergistic effect.Especially,Pd65Pb35 possessed the highest current density of about 3460 mA mgPd^−1 for the ethanol electrooxidation which was around 6.3 times higher than commercial Pd/C.The high-performance of Pd65Pb35 is attributed to the defect-rich and stable nanowire structure with optimized surface atomic arrangement,as evidenced by high resolution transmission electron microscopy measurements and long-time treatment in an acidic media.The differences in the morphologies and electrocatalytic activities of PdPb NWs with varied Pb contents have also been discussed and analyzed.
基金supported by the National Basic Research Program of China(2014CB931700)the Fundamental Research Funds for the Central Universities(30920130111017 and NE2012004)+1 种基金the Opened Fund of the State Key Laboratory on Integrated Optoelectronics(IOSKL2012KF06)the Program for Eastern Scholar at Shanghai Institutions of Higher Learning(2012-53)
文摘As the necessary components for various modern electronic and optoelectronic devices, novel transparent electrodes(TEs) with the low cost, abundance features, and comparable performance of indium tin oxide(ITO) are inquired materials. Metal nanowires(NWs) with the excellent photoelectric properties as next-generation TE candidates have widely applications in smart optoelectronic devices such as electronic skins, wearable electronics, robotic skins, flexible and stretchable displays. This review describes the synthetic strategies for the preparation of metal NWs, the assemble process for metal NW films,and the practical aspects of metal NW films with the desired properties in various low-cost, flexible,and solution-based photoelectric devices.
文摘Integration of molybdenum disulfide （MoS2） onto high surface area photocathod is highly desired to minimize the overpotential for the solar-powered hydrogen evolution reaction （HER）. Semiconductor nanowires （NWs） are beneficial use in photoelectrochemistry because of their large electrochemically availab surface area and inherent ability to decouple light absorption and the transpo of minority carriers. Here, silicon （Si） NW arrays were employed as a mod photocathode system for MoS2 wrapping, and their solar-driven HER activil was evaluated. The photocathode is made up of a well-defined MoSJTiO2/Si coaxial NW heterostructure, which yielded photocurrent density up to 15 mA/cm2 （at 0 V vs. the reversible hydrogen electrode （RHE）） with goo stability under the operating conditions employed. This work reveals the earth-abundant electrocatalysts coupled with high surface area NW electrod~ can provide performance comparable to noble metal catalysts for photocathod hydrogen evolution.
基金the National Natural Science Foundation of China(51732011,51702310,21431006,and 21761132008)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(21521001)+2 种基金the Key Research Program of Frontier Sciences,CAS(QYZDJ-SSW-SLH036)the Users with Excellence and Scientific Research Grant of Hefei Science Center of CAS(2015HSC-UE007)Anhui Provincial Natural Science Foundation(1808085ME115)。
文摘Conductive and adhesive hydrogels are promising materials for designing bioelectronics.To satisfy the high conductivity of bioelectronic devices,metal nanomaterials have been used to fabricate composite hydrogels.However,the fabrication of a conductive-nanomaterial-incorporated hydrogel with high performance is a great challenge because of the easy aggregation nature of conductive nanomaterials making processing difficult.Here,we report a kind of adhesive aero-hydrogel hybrid conductor(AAHC)with stretchable,adhesive and anti-bacteria properties by in situ formation of a hydrogel network in the aerogel-silver nanowires(AgNWs)assembly.The AgNWs with good conductivity are wellintegrated on the inner-surface of shape-memory chitosan aerogel,which created a conductive framework to allow hydrogel back-filling.Reinforcement by the aerogel-silver makes the hybrid hydrogel tough and stretchable.Functional groups from the hydrogel allow strong adhesion to wet tissues through molecular stitches.The inherent bacteria-killing ability of silver ions endows the conductive hydrogel with excellent anti-bacteria performance.The proposed facile strategy of aerogel-assisted assembly of metal nanomaterials with hydrogel opens a new route to incorporate functional nanoscale building blocks into hydrogels.
基金supported by the Outstanding Technical Talent Program of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant Nos.91123004,11104334,50825206,10834012 and 60801043)
文摘Free-standing metallic nanostructures are considered to be highly relevant to many branches of science and technology with applications of three dimensional metallic nanostructures ranging from optical reflectors,actuators,and antenna,to free-standing electrodes,mechanical,optical,and electrical resonators and sensors.Strain-induced out-of-plane fabrication has emerged as an effective method which uses relaxation of strain-mismatched materials.In this work,we report a study of the thermal annealing-induced shape modification of free-standing nanostructures,which was achieved by introducing compositional or microstructural nonuniformity to the nanowires.In particular gradient,segmented and striped hetero-nanowires were grown by focused-ion-beam-induced chemical vapor deposition,followed by rapid thermal annealing in a N2 atmosphere.Various free-standing nanostructures were produced as a result of the crystalline/grain growth and stress relief.
文摘An easy and effective solution based procedure for the synthesis of noble metal （both Au and Ag） tipped semiconductor nanomaterials is demonstrated where the metal precursors are taken in water and the semiconductors in organic medium, exploiting the phase transfer and reducing capability of suitably chosen ligands. The phase tranfer route is a generalised approach to form either Ag or Au tips on cadmium chalcogenide nanoparticles and nanorods. While multiple dots of noble metals are formed on the semiconductor nanomaterials initiall~ these coalesce into larger islands with time. The hybrids are characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, photoluminescence （PL）, ultraviolet-visible spectroscopy （UV-vis） and X-ray photoelectron spectroscopy （XPS）. A detailed FTIR analysis was also carried out to delineate the role of the ligands in the synthesis.
基金This work was supported by the Research Grant Council of Hong Kong(N_PolyU540/17)the Shenzhen Science and Technology Innovation Commission(JCYJ20180507183424383)the Hong Kong Polytechnic University(G-SB79 and G-YBPS).
文摘The atomic structure of quasi one-dimensional(1D) van der Waals materials can be regarded as the stacking of atomic chains to form thin flakes or nanoribbons, which substantially differentiates them from typical two-dimensional(2D) layered materials and 1D nanotube/nanowire array. Here we present our studies on quasi 1D gold selenide(AuSe) that possesses highly anisotropic crystal structure, excellent electrical conductivity, giant magnetoresistance, and unusual reentrant metallic behavior. The low inplane symmetry of AuSe gives rise to its high anisotropy of vibrational behavior. In contrast, quasi 1D AuSe exhibits high in-plane electrical conductivity along the directions of both atomic chains and perpendicular one, which can be understood as a result of strong interchain interaction. We found that AuSe exhibits a near quadratic nonsaturating giant magnetoresistance of 1841% with the magnetic field perpendicular to its in-plane. We also observe unusual reentrant metallic behavior, which is caused by the carrier mismatch in the multiband transport. Our works help to establish fundamental understandings on quasi 1D van der Waals semimetallic AuSe and identify it as a new candidate for exploring giant magnetoresistance and compensated semimetals.
基金supported by Solar Energy Initiative of the Knowledge Innovation Program of the Chinese Academy of Sciences (KGCX2-YW-395-3)
文摘In this work,we prepared silicon nanowires(Si NWs) on both fluorine-doped SnO 2(FTO) coated glass substrate and common glass substrate by catalytic thermal chemical vapor deposition(CVD) using indium film as the catalyst.It is confirmed that indium can catalyze the growth of Si NWs.More importantly,we found that tin generated in situ from the reduction of SnO 2 by indium can act as catalyst,which greatly enhances the growth of Si NWs on FTO substrate.The obtained Si NWs have a uniform crystalline-amorphous core-shell structure that is formed via vapor-liquid-solid and vapor-solid growth of silicon sequentially.This work provides a strategy to prepare Si NWs in high yield by catalytic thermal CVD using the low melting point metal catalysts.
基金supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan
文摘Optical near-field excitations were investigated on the basis of molecular alignment control of liquid crystals (LCs) on an optically rewritable nanostructure of photoreactive molecular thin films. Twisted nematic (TN) cells of LC molecules were constructed utilizing ITO substrates with 260 nm gratings of an azobenzene molecular thin film, fabricated using standing evanescent waves. The polarization changes of light transmitted through the TN cells, which were due to the alignment changes of LC molecules locally rubbed by the azobenzene nanogratings, were observed. Furthermore, we demonstrated local plasmon excitation of Au nanowires deposited on the azobenzene nanogratings using oblique vacuum evaporation, a phenomenon that produced strong anti-optical absorption spectra. The modulation of the local plasmon resonance in metallic nanowires decorated with LC molecules was confirmed.
基金This work was supported by the National Natural Science Foundation of China （51271095 and 51101090）, and PhD Program Foundation of Ministry of Education of China （20120002110038）.
文摘Metallic nanowire arrays （NWAs） possess wide application prospects due to their unique property, and the tailoring of NWAs＇ structure and morphology is of importance since it would significantly influence the per- formance of NWAs. In the present work, the morphology and structure evolution of the NWAs prepared by the newly developed die nanoimprinting technique has been investigated in detail. It was found that increasing pro- cessing temperature, time and pressure could increase the length of the nanowires and change the NWAs＇ morphol- ogy from monodispersed form to aggregated form. Increasing processing time and temperature within the supercooled liquid region would promote crystallization, while increasing processing pressure could suppress the crystallization. This work provided important insights into the structure and morphology evolution, and therefore, the tailoring of metallic NWAs prepared by die nanoimprinting through adjusting the process parameters.
文摘Strain engineering is a powerful tool to tailor the physical properties of materials coherently stacked in an epitaxial heterostructure. Such an approach, applied to the mature field of planar heteroepitaxy, has yielded a variety of new phenomena and devices. Recently, heteroepitaxial vertically aligned nanocomposites have emerged as alternatives to planar structures. Owing to the peculiar geometry of such nanoarchitectures, efficient strain control can be achieved, opening the way to novel functionalities. In this paper, we report a very large tensile axial strain in epitaxial transition metal nanowires embedded in an oxide matrix. We show that axial strains in excess of 1.5% can be sustained over a large thickness （a few hundred nanometers） in epitaxial nanowires having ultrasmall diameters （-3-6 nm）. The axial strain depends on the diameter of the nanowires, reflecting its epitaxial nature and the balance of interface and elastic energies. Furthermore, it is experimentally shown that such strain is metastable, in agreement with the calculations performed in the framework of the Frenkel-Kontorova model. The diameter dependence and metastability provide effective ways to control the strain, an appealing feature for the design of functional nanoarchitectures.
文摘We have recently demonstrated that GaAs nanosheets can be grown by metal-organic chemical vapor deposition （MOCVD）. Here, we investigate these nanosheets by secondary electron scanning electron microscopy （SE-SEM） and electron beam induced current （EBIC） imaging. An abrupt boundary is observed between an initial growth region and an overgrowth region in the nanosheets. The SE-SEM contrast between these two regions is attributed to the inversion of doping at the boundary. EBIC mapping reveals a p-n junction formed along the boundary between these two regions. Rectifying I-V behavior is observed across the boundary further indicating the formation of a p-n junction. The electron concentration （ND） of the initial growth region is around 1 × 10^18 cm^-3, as determined by both Hall effect measurements and low temperature photoluminescence （PL） spectroscopy. Based on the EBIC data, the minority carrier diffusion length of the nanosheets is 177 nm, which is substantially longer than the corresponding length in unpassivated GaAs nanowires measured previously.
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2012CB932400)China Postdoctoral Science Foundation(Grant No.2014M560934)
文摘In this study, the electrochemical behavior of monocrystalline bare Si and Ag-coated Si in hydrofluoric acid （HF） solutions with and without hydrogen peroxide （H202） was systematically tested with an electrochemical technique. By analyzing the po- larization curves, the corrosion processes were quantified and the etchants which govern the formation of silicon nanowires （SiNWs） were determined. It was discovered that both H202 and Ag enhanced the reduction reactions, irrespective of the con- ductivity type and doping concentration of Si. It is believed that the formation of SiNWs via Metal-Catalyzed Electroless Etching is a process controlled by cathodic reduction reactions.
基金partly supported by the National Natural Science Foundation of China(21673033)Sichuan Science and Technology Program(2020071)the Fundamental Research Founds for the Central Universities(ZYGX2019J024).
文摘Porous metal architectures are widely adopted as three-dimensional conducting scaffolds for constructing Li metal composite anodes,whereas their macropores hinder their practical application due to limited surface area and large pore size of few hundred micrometers.In this work,a network of Li_(x)Cu solid solution alloy nanowires is in situ formed via infiltrating molten Li-Cu alloy into Ni foam and subsequent cooling treatment,whereby a three-component composite anode consisting of Li metal,Li_(x)Cu alloy,and Ni foam is fabricated.The Li_(x)Cu nanowires nested as secondary frame split the macropores into micropores,enlarging the active surface area and inducing uniform Li deposition significantly.The lithiophilicity of the alloy wires and the shrunken void size built by the hierarchical architecture can further tune the nucleation and growth behavior of Li.The multiscale synergetic effect between the primary and secondary scaffold guarantees the composite anode sheet with extraordinarily long-term cycling stability even under high current rates.
基金supported by the National Natural Science Foundation of China(21373171),DOE-BES(DE-SC0006877)the NSF(CBET-0709113,CMMI-1100736),UTC Power,and Honda
文摘The oxidation of carbon monoxide is widely investigated for realistic and potential uses in energy production and environmental processes.As a probe reaction to the surface properties,it gives an insight into the relationship between the structure of active phase and catalytic performance.Noble metals alloyed with certain transition metals in the form of a nanoalloy exhibit enhanced catalytic activity for various reactions,especially when simultaneous activation of oxygen and CO is involved.This article highlights some of these insights into nanoalloy catalysts in which platinum group metal(PGM)is alloyed with a second and/or third transition metal(M/M′=Co,Fe,V,Ni,Ir,etc.),for catalytic oxidation of carbon monoxide in a gas phase.Recent studies have provided important insights into how the atomic-scale structures of the nanoalloy catalysts operate synergistically in activating oxygen and maneuvering surface oxygenated species.The exploration of atomic-scale chemical/structural ordering and coordination in correlation with the catalytic oxidation properties based on findings from ex-and in-situ synchrotron X-ray techniques is emphasized;for example,high-energy X-ray diffraction coupled to atomic-pair distribution function and X-ray absorption fine-structure spectroscopic analysis.The understanding of the detailed active sites of the nanoalloys has significant implications for the design of low-cost,active,and durable catalysts for sustainable energy production and environmental processes.
