GaAs nanowires(NWs)are ideal materials for preparing near-infrared photodetectors owing to their high charge carrier mobility and direct band gap.Although the performance of GaAs NW photodetectors can be enhanced by s...GaAs nanowires(NWs)are ideal materials for preparing near-infrared photodetectors owing to their high charge carrier mobility and direct band gap.Although the performance of GaAs NW photodetectors can be enhanced by surface passivation or doping,it still cannot meet the requirement for applications.In this paper we propose a method to greatly improve the performances of GaAs NW photodetectors by hot-hole injection via surface plasmon polaritons.In this case,the responsivity of a single GaAs NW photodetector is increased by a fact of 3.2 to 6.56 A·W^(-1) by attaching capsulelike Au nanoparticles to its surface.This research uses an efficient route to improve the NW photocurrent,which is also important for the development of a high-performance near-infrared NW photodetecor.展开更多
Platinum(Pt)-based electrocatalyst with low Pt content and high electrocatalytic performance is highly desired in fuel cell applications.Herein,we demonstrated that platinum-nickel(Pt-Ni)nanowires with an average comp...Platinum(Pt)-based electrocatalyst with low Pt content and high electrocatalytic performance is highly desired in fuel cell applications.Herein,we demonstrated that platinum-nickel(Pt-Ni)nanowires with an average composition of PtNi3 and a fishbone structure can be readily synthesized and used as an efficient electrocatalyst toward methanol oxidation reaction(MOR).The PtNi3 fishbone-like nanowires(PtNi3-FBNWs)present features such as richer Pt on the surface than in the bulk,high-index facets on the rough surface,and polyhedral facets at the ends of side chains.Such compositional and structural features could be determinative to the enhanced performance in the electrocatalysis of MOR.Compared with commercial 20%Pt/carbon black(Pt/C),the specific activity and mass activity of the PtNi3-FBNWs are enhanced by approximately 4.76 and 3.02 times,respectively.The stability of electrocatalysis is significantly improved as well.Such comprehensive enhancement indicates that the PtNi3-FBNWs would be a promising candidate toward MOR in fuel cells.展开更多
Quantum dots in nanowires （DINWs） are considered as important building blocks for novel nanoscale semiconductor optoelectronic devices. In this paper, pure axial heterojunction InGaN/GaN DINWs are grown by using pla...Quantum dots in nanowires （DINWs） are considered as important building blocks for novel nanoscale semiconductor optoelectronic devices. In this paper, pure axial heterojunction InGaN/GaN DINWs are grown by using plasma-assisted molecular beam epitaxy （PA-MBE） system. The InGaN quantum dots （QDs） are disk-like observed by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The diameter of QDs can be controlled by the growth conditions of nanowires （NWs）, while the thickness of QDs can be controlled by the growth time of lnGaN. Temperature-dependent photoluminescence （TDPL） measurements demonstrate that the PL peak of DINWs with small and uniform sizes shows a general red shift with increasing temperature. However, the PL peak of D1NWs with non-uniform sizes shows an abnormal blue shift with increasing temperature, which is due to different internal quantum efficiencies of the DINWs with different sizes.展开更多
Superlattice structures resulting from vacancy ordering have been observed in many materials.Here we report vacancy ordering behavior inⅢ_(2)Ⅵ_(3)nanowires.The formation of layer-like structural vacancies has been a...Superlattice structures resulting from vacancy ordering have been observed in many materials.Here we report vacancy ordering behavior inⅢ_(2)Ⅵ_(3)nanowires.The formation of layer-like structural vacancies has been achieved during the synthesis of In_(2)Se_(3)nanowires through a vapor-transport route.Doping In_(2)Se_(3)nanowires with small amounts of Ga during synthesis can completely change the structural vacancy ordering from a layer-like to a screw-like pattern for(In_(x)Ga_(1-x))_(2)Se_(3)nanowires.Lithium atoms can fill in the layer-like structural vacancies of In_(2)Se_(3)nanowires and generate new types of vacancy and lithium atom ordering superlattices.The screw-patterned vacancies of(In_(x)Ga_(1-x))_(2)Se_(3)nanowires show reversible lithium insertion.Our results contribute to the understanding of structure property correlations ofⅢ_(2)Ⅵ_(3)materials used in lithium ion storage,photovoltaics,and phase change memory.展开更多
Molecular dynamics(MD) simulations are performed to study the composition-dependent elastic modulus and thermal conductivity for carbon/silicon core/shell nanowires(NWs).For each concerned carbon/silicon core/shell NW...Molecular dynamics(MD) simulations are performed to study the composition-dependent elastic modulus and thermal conductivity for carbon/silicon core/shell nanowires(NWs).For each concerned carbon/silicon core/shell NW with a specified diameter,it is found that elastic modulus is reduced with a linear dependence on cross-sectional area ratio.The fact matches well with the results of theoretical model.Analysis based on the cross-sectional stress distribution indicates that the core region of core/shell NW is capable of functioning as a mechanical support.On the other hand,thermal conductivity also relies on the cross-sectional area ratio of amorphous silicon shell.The core/shell interface plays a considerable influence on the thermal transport property. The decreasing rate of thermal conductivity is gradually decreased as the composition of amorphous silicon shell increases.In addition,by calculating the phonon density of state,we demonstrate that the reduction in thermal conductivity of the core/shell NW stems from the increase of the low frequency modes and the depression of high-frequency nonpropagating diffusion modes.These results provide an effective way to modify the properties of core/shell NWs for related application.展开更多
Electromagnetic absorption(EMA)materials with light weight and harsh environmental robustness are highly desired and crucially important in the stealth of high-speed vehicles.However,meeting these two requirements is ...Electromagnetic absorption(EMA)materials with light weight and harsh environmental robustness are highly desired and crucially important in the stealth of high-speed vehicles.However,meeting these two requirements is always a great challenge,which excluded the most attractive lightweight candidates,such as carbon-based materials.In this study,SiC_(nw)-reinfbrced SiCNO(SiC_(nw)/SiCNO)composite aerogels were fabricated through the in-situ growth of SiC_(nw) in polymer-derived SiCNO ceramic aerogels by using catalyst-assisted microwave heating at ultra-low temperature and in short time.The phase composition,microstructure,and EMA property of the SiC_(nw)/SiCNO composite aerogels were systematically investigated.The results indicated that the morphology and phase composition of SiC_(nw)/SiCNO composite aerogels can be regulated easily by varying the microwave treatment temperature.The composite aerogels show excellent EMA property with minimum reflection loss of -23.9 dB@13.8 GHz,-26.5 dB@10.9 GHz,and -20.4 dB@14.5 GHz and the corresponding effective bandwidth of 5.2 GHz,3.2 GHz,and 4.8 GHz at 2.0 mm thickness for microwave treatment at 600℃,800℃,and 1000℃,respectively,which is much better than that of SiCN ceramic aerogels.The superior EMA performance is mainly attributed to the improved impedance matching,multireflection,multi-interfacial polarization,and micro current caused by migration of hopping electrons.展开更多
Materials and device architecture innovations are essential for further enhancing the performance of solar cells while potentially enabling their large-scale integration as a viable source of alternative energy.In thi...Materials and device architecture innovations are essential for further enhancing the performance of solar cells while potentially enabling their large-scale integration as a viable source of alternative energy.In this regard,tremendous research has been devoted in recent years with continuous progress in the field.In this article,we review the recent advancements in nanopillar-based photovoltaics while discussing the future challenges and prospects.Nanopillar arrays provide unique advantages over thin films in the areas of optical properties and carrier collection,arising from their three-dimensional geometry.The choice of the material system,however,is essential in order to gain the advantage of the large surface/interface area associated with nanopillars with the constraints different from those of the thin film devices.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62074018,12074045,61904017and 11804335)the Developing Project of Science and Technology of Jilin Province,China(Grant No.20200301052RQ)the Project of Education Department of Jilin Province,China(Grant Nos.JJKH20200763KJ and JJKH20210831KJ)。
文摘GaAs nanowires(NWs)are ideal materials for preparing near-infrared photodetectors owing to their high charge carrier mobility and direct band gap.Although the performance of GaAs NW photodetectors can be enhanced by surface passivation or doping,it still cannot meet the requirement for applications.In this paper we propose a method to greatly improve the performances of GaAs NW photodetectors by hot-hole injection via surface plasmon polaritons.In this case,the responsivity of a single GaAs NW photodetector is increased by a fact of 3.2 to 6.56 A·W^(-1) by attaching capsulelike Au nanoparticles to its surface.This research uses an efficient route to improve the NW photocurrent,which is also important for the development of a high-performance near-infrared NW photodetecor.
基金supported by the National Natural Science Foundation of China(Nos.61575049,51802054,and 51601046)the 100-Talent Program of Chinese Academy of Sciences,and the start-up funding from National Center for Nanoscience and Technology.
文摘Platinum(Pt)-based electrocatalyst with low Pt content and high electrocatalytic performance is highly desired in fuel cell applications.Herein,we demonstrated that platinum-nickel(Pt-Ni)nanowires with an average composition of PtNi3 and a fishbone structure can be readily synthesized and used as an efficient electrocatalyst toward methanol oxidation reaction(MOR).The PtNi3 fishbone-like nanowires(PtNi3-FBNWs)present features such as richer Pt on the surface than in the bulk,high-index facets on the rough surface,and polyhedral facets at the ends of side chains.Such compositional and structural features could be determinative to the enhanced performance in the electrocatalysis of MOR.Compared with commercial 20%Pt/carbon black(Pt/C),the specific activity and mass activity of the PtNi3-FBNWs are enhanced by approximately 4.76 and 3.02 times,respectively.The stability of electrocatalysis is significantly improved as well.Such comprehensive enhancement indicates that the PtNi3-FBNWs would be a promising candidate toward MOR in fuel cells.
基金This work was supported by the National Basic Research Program of China （No. 2013CB632804）, the National Natural Science Foundation of China （Grant Nos. 61176015, 61176059, 61210014, 61321004 and 61307024）, and the High Technology Research and Development Program of China （No. 2012AA05060 I）.
文摘Quantum dots in nanowires （DINWs） are considered as important building blocks for novel nanoscale semiconductor optoelectronic devices. In this paper, pure axial heterojunction InGaN/GaN DINWs are grown by using plasma-assisted molecular beam epitaxy （PA-MBE） system. The InGaN quantum dots （QDs） are disk-like observed by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The diameter of QDs can be controlled by the growth conditions of nanowires （NWs）, while the thickness of QDs can be controlled by the growth time of lnGaN. Temperature-dependent photoluminescence （TDPL） measurements demonstrate that the PL peak of DINWs with small and uniform sizes shows a general red shift with increasing temperature. However, the PL peak of D1NWs with non-uniform sizes shows an abnormal blue shift with increasing temperature, which is due to different internal quantum efficiencies of the DINWs with different sizes.
基金Y.C.acknowledges support from U.S.Department of Energy under the Award Number DE-FG36-08GOI8004.
文摘Superlattice structures resulting from vacancy ordering have been observed in many materials.Here we report vacancy ordering behavior inⅢ_(2)Ⅵ_(3)nanowires.The formation of layer-like structural vacancies has been achieved during the synthesis of In_(2)Se_(3)nanowires through a vapor-transport route.Doping In_(2)Se_(3)nanowires with small amounts of Ga during synthesis can completely change the structural vacancy ordering from a layer-like to a screw-like pattern for(In_(x)Ga_(1-x))_(2)Se_(3)nanowires.Lithium atoms can fill in the layer-like structural vacancies of In_(2)Se_(3)nanowires and generate new types of vacancy and lithium atom ordering superlattices.The screw-patterned vacancies of(In_(x)Ga_(1-x))_(2)Se_(3)nanowires show reversible lithium insertion.Our results contribute to the understanding of structure property correlations ofⅢ_(2)Ⅵ_(3)materials used in lithium ion storage,photovoltaics,and phase change memory.
基金This work was supported by the NationalNatural Science Foundation of China （Grant No. 61675234） and the Advanced Research Foundation of the National University of Defense Technology （Grant No. zk16-03-40）.
基金the China Postdoctoral Science Foundation and Fundamental Research Funds for the Central Universities(No.HIT NSRIF 2013031)
文摘Molecular dynamics(MD) simulations are performed to study the composition-dependent elastic modulus and thermal conductivity for carbon/silicon core/shell nanowires(NWs).For each concerned carbon/silicon core/shell NW with a specified diameter,it is found that elastic modulus is reduced with a linear dependence on cross-sectional area ratio.The fact matches well with the results of theoretical model.Analysis based on the cross-sectional stress distribution indicates that the core region of core/shell NW is capable of functioning as a mechanical support.On the other hand,thermal conductivity also relies on the cross-sectional area ratio of amorphous silicon shell.The core/shell interface plays a considerable influence on the thermal transport property. The decreasing rate of thermal conductivity is gradually decreased as the composition of amorphous silicon shell increases.In addition,by calculating the phonon density of state,we demonstrate that the reduction in thermal conductivity of the core/shell NW stems from the increase of the low frequency modes and the depression of high-frequency nonpropagating diffusion modes.These results provide an effective way to modify the properties of core/shell NWs for related application.
基金the financial support from the National Natural Science Foundation of China(Nos.U1904180 and 52072344)Excellent Young Scientists Fund of Henan Province(No.202300410369)+1 种基金Henan Province University Innovation Talents Support Program(No.21HASTIT001)China Postdoctoral Science Foundation(No.2021M692897).
文摘Electromagnetic absorption(EMA)materials with light weight and harsh environmental robustness are highly desired and crucially important in the stealth of high-speed vehicles.However,meeting these two requirements is always a great challenge,which excluded the most attractive lightweight candidates,such as carbon-based materials.In this study,SiC_(nw)-reinfbrced SiCNO(SiC_(nw)/SiCNO)composite aerogels were fabricated through the in-situ growth of SiC_(nw) in polymer-derived SiCNO ceramic aerogels by using catalyst-assisted microwave heating at ultra-low temperature and in short time.The phase composition,microstructure,and EMA property of the SiC_(nw)/SiCNO composite aerogels were systematically investigated.The results indicated that the morphology and phase composition of SiC_(nw)/SiCNO composite aerogels can be regulated easily by varying the microwave treatment temperature.The composite aerogels show excellent EMA property with minimum reflection loss of -23.9 dB@13.8 GHz,-26.5 dB@10.9 GHz,and -20.4 dB@14.5 GHz and the corresponding effective bandwidth of 5.2 GHz,3.2 GHz,and 4.8 GHz at 2.0 mm thickness for microwave treatment at 600℃,800℃,and 1000℃,respectively,which is much better than that of SiCN ceramic aerogels.The superior EMA performance is mainly attributed to the improved impedance matching,multireflection,multi-interfacial polarization,and micro current caused by migration of hopping electrons.
文摘Materials and device architecture innovations are essential for further enhancing the performance of solar cells while potentially enabling their large-scale integration as a viable source of alternative energy.In this regard,tremendous research has been devoted in recent years with continuous progress in the field.In this article,we review the recent advancements in nanopillar-based photovoltaics while discussing the future challenges and prospects.Nanopillar arrays provide unique advantages over thin films in the areas of optical properties and carrier collection,arising from their three-dimensional geometry.The choice of the material system,however,is essential in order to gain the advantage of the large surface/interface area associated with nanopillars with the constraints different from those of the thin film devices.
