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3D Atomic‐Scale Insights into Anisotropic Core–Shell‐Structured InGaAs Nanowires Grown by Metal–Organic Chemical Vapor Deposition
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Jiangtao Qu Sichao Du Tim Burgess Changhong Wang Xiangyuan Cui Qiang Gao Weichao Wang Hark Hoe Tan Hui Liu Chennupati Jagadish Yingjie Zhang Hansheng Chen Mansoor Khan Simon Ringer Rongkun Zheng 《Advanced materials (Deerfield Beach, Fla.)》2017,29(31)
III–V ternary InGaAs nanowires have great potential for electronic and optoelectronic device applications; however, the 3D structure and chemistry at the atomic‐scale inside the nanowires remain unclear, which hinders tailoring the nanowires for specific applications. Here, atom probe tomography is used in conjunction with a first‐principles simulation to investigate the 3D structure and chemistry of InGaAs nanowires, and reveals i) the nanowires form a spontaneous core–shell structure with a Ga‐enriched core and an In‐enriched shell, due to different growth mechanisms in the axial and lateral directions; ii) the shape of the core evolves from hexagon into Reuleaux triangle and grows larger, which results from In outward and Ga inward interdiffusion occurring at the core–shell interface; and iii) the irregular hexagonal shell manifests an anisotropic growth rate on {112}A and {112}B facets. Accordingly, a model in terms of the core–shell shape and chemistry evolution is proposed, which provides fresh insights into the growth of these nanowires. 相似文献
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Programmable Negative Differential Resistance Effects Based on Self‐Assembled Au@PPy Core–Shell Nanoparticle Arrays
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Jianzhong Zheng Junchang Zhang Zi Wang Liubiao Zhong Yinghui Sun Zhiqiang Liang Youyong Li Lin Jiang Xiaodong Chen Lifeng Chi 《Advanced materials (Deerfield Beach, Fla.)》2018,30(35)
The negative differential resistance (NDR) effect observed in conducting polymer/Au nanoparticle composite devices is not yet fully clarified due to the random and disordered incorporation of Au nanoparticles into conducting polymers. It remains a formidable challenge to achieve the sequential arrangement of various components in an optimal manner during the fabrication of Au nanoparticle/conducting polymer composite devices. Here, a novel strategy for fabricating Au nanoparticle/conducting polymer composite devices based on self‐assembled Au@PPy core–shell nanoparticle arrays is demonstrated. The interval between the two Au nanoparticles can be precisely programmed by modulating the thickness of the shell and the size of the core. Programmable NDR is achieved by regulating the spacer between two Au nanoparticles. In addition, the Au/conducting polymer composite device exhibits a reproducible memory effect with read–write–erase characteristics. The sequentially controllable assembly of Au@PPy core–shell nanoparticle arrays between two microelectrodes will simplify nanodevice fabrication and will provide a profound impact on the development of new approaches for Au/conducting polymer composite devices. 相似文献
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Jinyou Xu Katya Rechav Ronit Popovitz‐Biro Iftach Nevo Yishay Feldman Ernesto Joselevich 《Advanced materials (Deerfield Beach, Fla.)》2018,30(20)
1D core–shell heterojunction nanostructures have great potential for high‐performance, compact optoelectronic devices owing to their high interface area to volume ratio, yet their bottom‐up assembly toward scalable fabrication remains a challenge. Here the site‐controlled growth of aligned CdS–CdSe core–shell nanowalls is reported by a combination of surface‐guided vapor–liquid–solid horizontal growth and selective‐area vapor–solid epitaxial growth, and their integration into photodetectors at wafer‐scale without postgrowth transfer, alignment, or selective shell‐etching steps. The photocurrent response of these nanowalls is reduced to 200 ns with a gain of up to 3.8 × 103 and a photoresponsivity of 1.2 × 103 A W?1, the fastest response at such a high gain ever reported for photodetectors based on compound semiconductor nanostructures. The simultaneous achievement of sub‐microsecond response and high‐gain photocurrent is attributed to the virtues of both the epitaxial CdS–CdSe heterojunction and the enhanced charge‐separation efficiency of the core–shell nanowall geometry. Surface‐guided nanostructures are promising templates for wafer‐scale fabrication of self‐aligned core–shell nanostructures toward scalable fabrication of high‐performance compact photodetectors from the bottom‐up. 相似文献
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Metallic Nanogaps: Facile Preparation of Ultrasmall Void Metallic Nanogap from Self‐Assembled Gold–Silica Core–Shell Nanoparticles Monolayer via Kinetic Control (Adv. Mater. 29/2015)
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Yuna Shin Jihwan Song Dongchoul Kim Taewook Kang 《Advanced materials (Deerfield Beach, Fla.)》2015,27(29):4388-4388
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Wide‐Range Tunable Fluorescence Lifetime and Ultrabright Luminescence of Eu‐Grafted Plasmonic Core–Shell Nanoparticles for Multiplexing
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Jun Zhang Feng Song Zhubing He Yanling Liu Zhanyao Chen Shangxin Lin Ling Huang Wei Huang 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(3):397-404
Wide‐range, well‐separated, and tunable lifetime nanocomposites with ultrabright fluorescence are highly desirable for applications in optical multiplexing such as multiplexed biological detection, data storage, and security printing. Here, a synthesis of tunable fluorescence lifetime nanocomposites is reported featuring europium chelate grafted onto the surface of plasmonic core–shell nanoparticles, and systematically investigated their optical performance. In a single red color emission channel, more than 12 distinct fluorescence lifetime populations with high fluorescence efficiency (up to 73%) are reported. The fluorescence lifetime of Eu‐grafted core–shell nanoparticles exhibits a wider tunable range, possesses larger lifetime interval and is more sensitive to separation distance than that of ordinary Eu‐doping core–shell type. These superior performances are attributed to the unique nanostructure of Eu‐grafed type. In addition, these as‐prepared nanocomposites are used for security printing to demonstrate optical multiplexing applications. The optical multiplexing experiments show an interesting pseudo‐information “a rabbit in a well” and conceal the real message “NKU.” 相似文献
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The deliberate tailoring of nanoparticles supported on oxides, dispersed in dendrimers and encapsulated in monolayer shells could lead to novel catalytic applications. The study of core–shell assembled gold or alloy nanoparticles for electrocatalytic oxidation of carbon monoxide and methanol stems, in part, from recent insights in core–shell reactivities and, in part, from surprising findings of catalytic activities of oxide‐supported gold nanoparticles. Monolayer‐encapsulated metallic nanoparticles serve as intriguing model building blocks towards catalysts. Whether such core–shell nanoparticles can in general be developed into aggregation‐ and poison‐resistant catalysts of high catalytic activities rests with our capabilities in catalytic activation and structural manipulation. 相似文献
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Zheyu Shen Jibin Song Zijian Zhou Bryant C. Yung Maria A. Aronova Yan Li Yunlu Dai Wenpei Fan Yijing Liu Zihou Li Huimin Ruan Richard D. Leapman Lisen Lin Gang Niu Xiaoyuan Chen Aiguo Wu 《Advanced materials (Deerfield Beach, Fla.)》2018,30(33)
Gd‐based T 1‐weighted contrast agents have dominated the magnetic resonance imaging (MRI) contrast agent market for decades. Nevertheless, they are reported to be nephrotoxic and the U.S. Food and Drug Administration has issued a general warning concerning their use. In order to reduce the risk of nephrotoxicity, the MRI performance of the Gd‐based T 1‐weighted contrast agents needs to be improved to allow a much lower dosage. In this study, novel dotted core–shell nanoparticles (FeGd‐HN3‐RGD2) with superhigh r 1 value (70.0 mM?1 s?1) and very low r 2/r 1 ratio (1.98) are developed for high‐contrast T 1‐weighted MRI of tumors. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay and histological analyses show good biocompatibility of FeGd‐HN3‐RGD2. Laser scanning confocal microscopy images and flow cytometry demonstrate active targeting to integrin αvβ3 positive tumors. MRI of tumors shows high tumor ΔSNR for FeGd‐HN3‐RGD2 (477 ± 44%), which is about 6‐7‐fold higher than that of Magnevist (75 ± 11%). MRI and inductively coupled plasma results further confirm that the accumulation of FeGd‐HN3‐RGD2 in tumors is higher than liver and spleen due to the RGD2 targeting and small hydrodynamic particle size (8.5 nm), and FeGd‐HN3‐RGD2 is readily cleared from the body by renal excretion. 相似文献
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Epitaxial Growth of Lattice‐Mismatched Core–Shell TiO2@MoS2 for Enhanced Lithium‐Ion Storage
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Rui Dai Anqi Zhang Zhichang Pan Abdullah M. Al‐Enizi Ahmed A. Elzatahry Linfeng Hu Gengfeng Zheng 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(20):2792-2799
Core–shell structured nanohybrids are currently of significant interest due to their synergetic properties and enhanced performances. However, the restriction of lattice mismatch remains a severe obstacle for heterogrowth of various core–shells with two distinct crystal structures. Herein, a controlled synthesis of lattice‐mismatched core–shell TiO2@MoS2 nano‐onion heterostructures is successfully developed, using unilamellar Ti0.87O2 nanosheets as the starting material and the subsequent epitaxial growth of MoS2 on TiO2. The formation of these core–shell nano‐onions is attributed to an amorphous layer‐induced heterogrowth mechanism. The number of MoS2 layers can be well tuned from few to over ten layers, enabling layer‐dependent synergistic effects. The core–shell TiO2@MoS2 nano‐onion heterostructures exhibit significantly enhanced energy storage performance as lithium‐ion battery anodes. The approach has also been extended to other lattice‐mismatched systems such as TiO2@MoSe2, thus suggesting a new strategy for the growth of well‐designed lattice‐mismatched core–shell structures. 相似文献
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Damien Hudry Ian A. Howard Radian Popescu Dagmar Gerthsen Bryce S. Richards 《Advanced materials (Deerfield Beach, Fla.)》2019,31(26)
The production of upconverting nanostructures with tailored optical properties is of major technological interest, and rapid progress toward the realization of such production has been made in recent years. Ultimately, accurate understanding of nanostructure organization will lead to design rules for accurately tailoring optical properties. Here, the context of open questions still of general importance to the upconversion and nanocrystal communities is presented, with a particular emphasis on the structure–property relationships of core–shell upconverting nanocrystals. Although the optical properties of the latter have been thoroughly investigated, little is known regarding their atomic‐scale organization. Indeed, solving the atomic‐scale structure of such nanomaterials is challenging because of their intrinsic nonperiodic nature. Familiar concepts of crystallography are no longer appropriate; chemical and structural modulation waves must be introduced. To reveal the exact core–shell structures, innovative characterization techniques need to be applied and developed, as discussed herein. The continued development and application of structural characterization techniques will be vital to consolidate the currently incomplete link between atomic‐scale structure and upconversion properties. This will ultimately provide a valuable contribution to the emerging detailed guidelines on how to better design upconverting nanostructures to achieve given optical properties in terms of efficiency, absorption, spectral emission, and dynamics. 相似文献
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CdS@SiO2 Core–Shell Electroluminescent Nanorod Arrays Based on a Metal–Insulator–Semiconductor Structure
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Chunfeng Wang Dengfeng Peng Jing Zhao Rongrong Bao Tianfeng Li Li Tian Lin Dong Changyu Shen Caofeng Pan 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(41):5734-5740
Enormous advancement has been achieved in the field of one‐dimensional (1D) semiconductor light‐emitting devices (LEDs), however, LEDs based on 1D CdS nanostructures have been rarely reported. The fabrication of CdS@SiO2 core–shell nanorod array LEDs based on a Au–SiO2–CdS metal–insulator–semiconductor (MIS) structure is presented. The MIS LEDs exhibit strong yellow emission with a low threshold voltage of 2.7 V. Electroluminescence with a broad emission ranging from 450 nm to 800 nm and a shoulder peak at 700 nm is observed, which is related to the defects and surface states of the CdS nanorods. The influence of the SiO2 shell thickness on the electroluminescence intensity is systematically investigated. The devices have a high light‐emitting spatial resolution of 1.5 μm and maintain an excellent emission property even after shelving at room temperature for at least three months. Moreover, the fabrication process is simple and cost effective and the MIS device could be fabricated on a flexible substrate, which holds great potential for application as a flexible light source. This prototype is expected to open up a new route towards the development of large‐scale light‐emitting devices with excellent attributes, such as high resolution, low cost, and good stability. 相似文献
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Min Eui Lee Seunggon Lee Jaewon Choi Hyoung‐Joon Jin Seungyong Han Young Soo Yun 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(37)
Anode‐free sodium metal batteries (AF‐SMBs) can deliver high energy and enormous power, but their cycle lives are still insufficient for them to be practical as a power source in modern electronic devices and/or grid systems. In this study, a nanohybrid template based on high aspect‐ratio silver nanofibers and nitrogen‐rich carbon thin layers as a core–shell structure is designed to improve the Coulombic efficiency (CE) and cycling performance of AF‐SMBs. The catalytic nanohybrid templates dramatically reduce the voltage overshooting caused by metal nucleation to one‐fifth that of a bare Al foil electrode (≈6 mV vs ≈30 mV), and high average CE values of >99% are achieved over a wide range of current rates from 0.2 to 8 mA cm?2. Moreover, exceptionally long cycle lives for more than 1600 cycles and an additional 1500 cycles are achieved with a highly stable CE of >99.9%. These results show that AF‐SMBs are feasible with the nanohybrid electrode system. 相似文献
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A Chemical Precipitation Method Preparing Hollow–Core–Shell Heterostructures Based on the Prussian Blue Analogs as Cathode for Sodium‐Ion Batteries
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Yongxin Huang Man Xie Ziheng Wang Ying Jiang Ying Yao Shuaijie Li Zehua Li Li Li Feng Wu Renjie Chen 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(28)
Prussian blue and its analogs are regarded as the promising cathodes for sodium‐ion batteries (SIBs). Recently, various special structures are constructed to improve the electrochemical properties of these materials. In this study, a novel architecture of Prussian blue analogs with large cavity and multilayer shells is investigated as cathode material for SIBs. Because the hollow structure can relieve volume expansion and core–shell heterostructure can optimize interfacial properties, the complex structure materials exhibited a highly initial capacity of 123 mA h g?1 and a long cycle life. After 600 cycles, the reversible capacity of the electrode still maintains at 102 mA h g?1 without significant voltage decay, indicating a superior structure stability and sodium storage kinetics. Even at high current density of 3200 mA g?1, the electrode still delivers a considerable capacity above 52 mA h g?1. According to the electrochemical analysis and ex‐situ measurements, it can be inferred that the enhanced apparent diffusion coefficient and improved insertion/extraction performance of electrode have been obtained by building this new morphology. 相似文献
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Core–Shell Si/C Nanospheres Embedded in Bubble Sheet‐like Carbon Film with Enhanced Performance as Lithium Ion Battery Anodes
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Wenyue Li Yongbing Tang Wenpei Kang Zhenyu Zhang Xia Yang Yu Zhu Wenjun Zhang Chun‐Sing Lee 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(11):1345-1351
Due to its high theoretical capacity and low lithium insertion voltage plateau, silicon has been considered one of the most promising anodes for high energy and high power density lithium ion batteries (LIBs). However, its rapid capacity degradation, mainly caused by huge volume changes during lithium insertion/extraction processes, remains a significant challenge to its practical application. Engineering Si anodes with abundant free spaces and stabilizing them by incorporating carbon materials has been found to be effective to address the above problems. Using sodium chloride (NaCl) as a template, bubble sheet‐like carbon film supported core–shell Si/C composites are prepared for the first time by a facile magnesium thermal reduction/glucose carbonization process. The capacity retention achieves up to 93.6% (about 1018 mAh g?1) after 200 cycles at 1 A g?1. The good performance is attributed to synergistic effects of the conductive carbon film and the hollow structure of the core–shell nanospheres, which provide an ideal conductive matrix and buffer spaces for respectively electron transfer and Si expansion during lithiation process. This unique structure decreases the charge transfer resistance and suppresses the cracking/pulverization of Si, leading to the enhanced cycling performance of bubble sheet‐like composite. 相似文献
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Mengqi Xiao Huai Yang Wanfu Shen Chunguang Hu Kai Zhao Qiang Gao Longfei Pan Liyuan Liu Chengliang Wang Guozhen Shen Hui‐Xiong Deng Hongyu Wen Zhongming Wei 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(7)
Structural symmetry is a simple way to quantify the anisotropic properties of materials toward unique device applications including anisotropic transportation and polarization‐sensitive photodetection. The enhancement of anisotropy can be achieved by artificial symmetry‐reduction design. A core–shell SbI3/Sb2O3 nanowire, a heterostructure bonded by van der Waals forces, is introduced as an example of enhancing the performance of polarization‐sensitive photodetectors via symmetry reduction. The structural, vibrational, and optical anisotropies of such core–shell nanostructures are systematically investigated. It is found that the anisotropic absorbance of a core–shell nanowire is obviously higher than that of two single compounds from both theoretical and experimental investigations. Anisotropic photocurrents of the polarization‐sensitive photodetectors based on these core–shell SbI3/Sb2O3 van der Waals nanowires are measured ranging from ultraviolet (UV) to visible light (360–532 nm). Compared with other van der Waals 1D materials, low anisotropy ratio (Imax/Imin) is measured based on SbI3 but a device based on this core–shell nanowire possesses a relatively high anisotropy ratio of ≈3.14 under 450 nm polarized light. This work shows that the low‐symmetrical core–shell van der Waals heterostructure has large potential to be applied in wide range polarization‐sensitive photodetectors. 相似文献