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W_2C nanorods or WC nanodots are prepared via an easy,shape-controllable and large-scale preparation technique.Results reveal that each of the W_2C nanorods and WC nanodots has a peroxidase-like activity.Besides,the peroxidase-like activity of W_2C is the first time to be demonstrated.The catalytic efficiency of W_2C nanorods is much higher than that of WC nanodots and chemical condition range of W_2C can be wider than that of WC,which indicates that W_2C is likely to be used as artificial mimetic peroxidase or in-situ amplified colorimetric immunoassay. 相似文献
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利用溶剂热法合成了一维的氧化钨纳米线, 通过掺入适量单壁碳纳米管(SWNT)制备了基于氧化钨纳米线-SWNT 复合结构的室温气敏元件并评价了其对NO2气体的室温敏感性能. 利用X射线与扫描电子显微镜表征了材料的微结构, 结果表明, 合成的氧化钨纳米线具有单斜的W18O49结构, 复合材料中SWNT被包埋在氧化钨纳米线中间. 气敏性能测试结果表明, 氧化钨纳米线-SWNT复合结构气敏元件在室温下对NO2气体表现出了高的灵敏度和超快的响应特性; 较低的SWNT掺入量对获得好的气敏性能有利. 分析了基于复合结构材料气敏元件的可能的气敏机理, 认为元件良好的室温敏感性能与SWNT掺入在复合结构材料中引入大量的贯穿气孔和p-n异质结有关. 相似文献
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碳纳米点作为新兴的碳纳米材料,具备制备成本低、尺寸小、低毒、生物相容性高、水溶性好、易修饰、光物理性质独特等诸多优点,在生物医疗领域展现了独有的优势和应用前景。由于具有丰富的表面官能团,碳纳米点可以与靶向配体、医学影像造影剂、核酸、化学药物、光敏剂、光热转换试剂等功能性诊断治疗试剂相互作用形成复合物。目前,碳纳米点及其复合物在医学影像、基因治疗、化学药物治疗、光热、光动力治疗等生物医学诊断治疗领域的应用正在被广泛的开发和报道。这些工作对开发基于碳纳米点的医学诊断治疗试剂及其临床推进具有重要意义,为推进人类重大疾病的个体化、可视化、非入侵式、小损伤的诊断治疗提供一种新的药物体系。本文将关注应用于诊断治疗领域的碳纳米点及其复合物的设计、构建及性能研究,对已报道的基于碳纳米点的诊断治疗试剂在生物医疗领域的研究进展进行总结和讨论。 相似文献
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In this paper, a large number of the micro/nano-sized tungsten single-crystalline whiskers were fabricated via a vapour deposition method. The morphology and structure of the whiskers were investigated using scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The factors affecting the growth of tungsten whiskers were systematically studied, including temperature, holding time and the position of Si substrates. Results indicated that temperature, holding time and position of the Si substrates have significant effects on the growth of tungsten whiskers. 相似文献
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CAO Limin ZHANG Ze & WANG Wenkui . Key Laboratory of Metastable Materials Science Technology Yanshan University Qinhuangdao China . Institute of Physics Chinese Academy of Sciences Beijing China 《中国科学G辑(英文版)》2004,47(5):621-633
One-dimensional (1D) nanostructures, such as nanotubes and nanowires, have gen-erated worldwide interest due to their nano-scale sizes, high length-to-diameter ratios, highly anisotropic properties, various unique structures, and wide technological applica-tions. 1D nanostructures are the smallest dimension structures that can be used for effi-cient transport of electrons, vacancies, and excitations, and are thus critical building blocks in the construction of nanoscale electronic and mechanic… 相似文献
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CAO Limin ZHANG Ze & WANG Wenkui . Key Laboratory of Metastable Materials Science Technology College of Materials Science Engineering Yanshan University Qinhuangdao China . Institute of Physics Chinese Academy of Sciences Beijing China 《中国科学G辑(英文版)》2004,47(4):403-415
The elemental boron and boron-rich compounds constitute a fascinating class of materials because of their vast variety of unique structures, extraordinary three-center electron-deficient bonds, and fascinating properties[1—4]. In general, they have an inverted molecular-like structure, which is characterized by three-dimensional skeletons of B12 icosahedra or icosahedral fragments. Furthermore, these B12 icosahedra are linked together by two-center covalent bonds, which lead to the intra-clus… 相似文献
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钨氧化物纳米线在高灵敏度低功耗气体传感器中极具应用潜力, 且通过掺杂改性可进一步显著改善其敏感性能. 本文以WCl6为钨源, NH4VO3为掺杂剂, 采用溶剂热法合成了钒掺杂的W18O49纳米线. 利用扫描电镜、透射电镜、X射线衍射、X射线光电子能谱仪表征了纳米线的微结构, 并利用静态气敏性能测试系统评价了掺杂纳米线的NO2敏感性能. 研究结果表明: 五价钒离子受主掺杂进入氧化钨晶格结构, 抑制了纳米线沿轴向的生长并导致了纳米线束的二次集聚; 室温下, 钒掺杂W18O49纳米线接触NO2气体后表现出反常的p型响应特性; 随工作温度逐渐升高至约110 ℃时, 发生从p型到n型的电导特性转变; 该掺杂纳米线气敏元件对浓度低至80 ppb (1 ppb=10-9) 的NO2气体具有明显的室温敏感响应和良好的响应稳定性. 分析并探讨了钒掺杂W18O49纳米线的高室温敏感特性及其p-n电导转型机理, 认为钒掺杂W18O49纳米线在室温下的良好敏感响应及反常p型导电性与掺杂纳米线表面高密度非稳表面态诱导的低温气体强吸附有关.关键词：氧化钨纳米线气体传感器室温灵敏度 相似文献
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Sungan Do Woosung Kwon Young‐Hoon Kim So Rang Kang Taehyung Lee Tae‐Woo Lee Shi‐Woo Rhee 《Advanced Optical Materials》2016,4(2):276-284
In this work, nitrogen and sulfur‐doped carbon nanodots (CNDs) have been synthesized from ethylenediamine‐N,N′‐diacetic acid and 2,2′‐(ethylenedithio)diacetic acid, respectively. The method used in this work features the use of “single” molecular precursors that contain both carbon and dopant atoms, which allows examining the effects of doping in a molecular level. The effects of doping on the electronic structure of CNDs could be examined by a series of spectroscopic measurements including UV–vis absorption and photoluminescence. It is found that doping gives rise to new light absorption and photoluminescence bands at around 500 nm. Finally, light‐emitting diodes (LEDs) with the CNDs synthesized have been demonstrated to show that the electronic states induced by direct doping influence their electroluminescence. Such LEDs successfully exhibit broadband electroluminescence covering the visible light range from 500 to 700 nm, resulting in bright pure white light whose CIE (Commission Internationale d'Éclairage) coordinate is (0.2894, 0.3351). 相似文献
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Jie Wang Fei Peng Yimei Lu Yiling Zhong Siyi Wang Meifeng Xu Xiaoyuan Ji Yuanyuan Su Liangsheng Liao Yao He 《Advanced Optical Materials》2015,3(1):103-111
An easy and green synthetic strategy for the one‐pot large‐scale preparation of carbon nanodots (C‐dots) is demonstrated. The C‐dots have a series of excellent optical features such as strong fluorescence and excitation‐wavelength‐dependent photoluminescence properties. Notably, C‐dots can be rapidly and facilely achieved on a large scale (e.g., 0.3 g C‐dots/25 min) by using cheap, accessible, and natural materials (e.g., milk, honey, silk, hair, lemon, and magnolia) as the green carbonaceous precursor. The as‐prepared C‐dots, which are shown to serve as high‐performance fluorescent stains, are superbly suitable for a variety of optics‐related applications, including in vitro and in vivo bioimaging, printing inks, and sensors. Eventually, this kind of microwave‐assisted strategy could serve as a powerful tool for synthesizing large‐scale C‐dots with strong fluorescence, holding great promise for myriad optics‐related applications. 相似文献
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Carbon nanodots(CDs) with visible absorption band and TiO_2 are integrated to enhance the photosensitivity of TiO_2.The CD/TiO_2 nanocomposites show obvious CD-coverage-dependent photocatalytic performance. The CD/TiO_2 nanocomposites with moderate CD coverge exhibit the highest photocatalytic activity after being irradiated with visible light, which is more excellent than that of TiO_2. Too little CD coverage could result in poor visible light absorption, which limits the photocatalytic performance of CD/TiO_2 nanocomposites. While, too much CD coverage weakens the photocatalytic activity of CD/TiO_2 nanocomposites by restraining the extraction of conduction band electrons within TiO_2 to generate active oxygen radicals and the electron transfer(ET) process from CDs to TiO_2. These results indicate that rational regulation of CD coverage and the realization of efficient ET process are important means to optimize the photocatalytic performance of CD/TiO_2 nanocomposites. 相似文献
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纳米结构的氧化钨有高比表面积和气体吸附能力,在气体传感器领域得到了广泛研究.本文采用磁控溅射金属钨薄膜和两步热氧化工艺在二氧化硅衬底上生长出氧化钨纳米线.通过改变第二步氧化温度,研究退火温度对氧化钨纳米线气敏特性的影响.采用扫描电子显微镜、X射线衍射仪、X射线光电子能谱分析仪和透射射电子显微镜表征材料的微观特性和晶体结构,利用静态配气法测试气敏性能.研究结果表明,经过退火处理后氧化钨纳米线密度略微降低,300℃比400℃退火后的氧化钨结晶性差,对应的表面态含量多,有利于室温气体敏感性.测试NO_2的气敏性能,经过对比得出300℃退火温度下制备的氧化钨纳米线在室温下表现出较很好的气敏响应,对6 ppm(1 ppm=10~(-6))NO_2达到2.5,对检测极限0.5 ppm NO_2响应达1.37.氧化钨纳米线在室温下表现出反常的P型响应,是因为氧化钨纳米线表面被氧气吸附形成反型层,空穴取代电子成为主要载流子所致. 相似文献
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Dawei Yang Zhenzhen Guo Jing Wang Yakang Jin Qian Mei Peng Miao 《Particle & Particle Systems Characterization》2019,36(10)
In this work, a fluorescent method is developed for ultrasensitive detection of virus DNA, coupling DNA‐modified carbon nanodots (CDs) and an isothermal amplification technology. The sensitivity is significantly improved with cyclic strand displacement polymerization and highly luminescent CDs. Taking the hemagglutinin7 (H7) gene and neuraminidase 9 (N9) gene as examples, the limits of detection are 4.6 × 10?15 and 3.4 × 10?15 m , respectively. Furthermore, the proposed method is highly selective and capable of detecting target sequences in biological samples, indicating great potential for applications in life science research and clinical diagnosis. 相似文献
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Dawei Yang Xujia Zhang Xinyue Kou Xuejun Shao Peng Miao 《Particle & Particle Systems Characterization》2020,37(4):1900488
In this work, an ultrasensitive method for trace protein detection based on fluorescent carbon nanodots and hybridization chain reaction (HCR) is designed. Generally, the synthesized bright carbon nanodots are conjugated with two hairpin-structured DNA probes, respectively, which act as subsequent HCR fuel strands. Since single-stranded parts of DNA probes could be easily absorbed on graphene oxide (GO) nanosheets, fluorescence emission of carbon nanodots is effectively quenched via fluorescence resonance energy transfer. However, in the presence of target protein, the aptamer sequence in another hairpin-structured DNA probe specially interacts with target and the hairpin is opened. A single-stranded region is thus exposed, which initiates HCR by coupling with the DNA fuel strands on carbon nanodots. The formed HCR product displays a rigid, long double-stranded structure, which facilitates the release of carbon nanodots from GO surface. As a result, fluorescence of carbon nanodots is recovered and initial concentration of target protein can be estimated. This protein detection method shows a favorable linear response with a low limit of detection (2.3 fg mL−1). Furthermore, it is highly selective and capable of detecting target in biological fluids like serum samples, which demonstrates the promising applications of this method. 相似文献
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Using a femtosecond resolved up‐conversion technique, the ultrafast carrier dynamics in fluorescent carbon nanodots are investigated in order to shed light on the mysterious origins of their fluorescence. These experiments reveal that the fluorescence of carbon nanodots consists of two spectral overlapped bands that can be ascribed to the intrinsic and extrinsic fluorescence. The intrinsic band exhibits a small bandwidth of 175 meV at 459 nm, and it is attributed to the sp2 nano domains. The extrinsic band originates from the surface states with a much broader bandwidth of 450 meV. The relaxation with time constants of a few picoseconds, tens of picoseconds, and a few nanoseconds are attributed to optical phonon scattering, acoustic phonon scattering, and carrier (e–h pair) recombination, respectively. A fast trapping is observed from the nano domains into the surface states with a time constant of 400 fs. The excitation wavelength‐dependent fluorescence can arise from the abundant carboxyl functional groups on the surface. 相似文献
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本文采用分子动力学模拟方法研究了扶手型碳纳米管包裹Ni纳米线的复合结构, 主要讨论内部Ni纳米线的螺旋度和热稳定性.结果表明, Ni纳米线为多壳层螺旋结构, 各壳层是由多条Ni原子链螺旋而成,不同层的螺旋度不同,内层的螺旋度明显大于外层. 当每层的Ni原子链条数为3的整数倍时,其螺旋度最大. Ni纳米线的螺旋度与碳纳米管的管径相关,各层螺旋度的大小随管径的增加有明显的周期性变化. 碳纳米管对Ni纳米线有很好的保护作用,即使是高温对Ni纳米线的结构及螺旋度也影响很小. 相似文献