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石墨烯量子点凭借其良好的水溶性、低生物毒性等特点,被不断尝试应用于生物成像领域,但其有限的荧光性能限制了其进一步应用。为改善石墨烯量子点的荧光性能以及进一步揭示石墨烯量子点的制备机理,本文对聚乙烯亚胺(PEI)功能化石墨烯量子点的制备条件进行了探索,讨论了不同反应时间、制备温度以及混悬液pH值对其荧光性能的影响。测试结果显示,当混悬液pH值为12时,在反应釜中经过200 ℃高温反应20 h,所制备的功能化石墨烯量子点能取得良好的紫外吸收峰和荧光性能,同时达到较高的量子产量。 相似文献
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Manuel Algarra Ana Reis Iulius Bobos Bruno B. Campos José Jiménez-Jiménez Ramón Moreno-Tost 《Journal of Dispersion Science and Technology》2013,34(8):1139-1143
Synthesis, characterization, and the optical behavior of CdS quantum dots nanoparticles were studied confined in clays. An alternative synthesis approach in different natural clays K-10 bentonite, Na-montemorillonite, halloysite, and saponite was carried out. The composite materials were characterized by XRD and FTIR spectroscopy, energy dispersive, scanning, and transmission electron microscopy. After CdS-QDs formation, the synthesized materials became fluorescent with emission wavelengths (average and standard deviation of the maximum wavelength; full width of half maximum): K-10 bentonite-CdS (590 ± 5 nm; 183 nm); Na-montmorillonite-CdS (550 ± 3 nm; 219 nm); saponite-CdS (550 ± 5 nm; 219 nm), and halloysite-CdS (590 ± 8 nm; 185 nm). (Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Dispersion Science and Technology to view the free supplemental file.) 相似文献
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Manuel Algarra Ana Reis José Jiménez-Jiménez Ramón Moreno-Tost Joaquim C. G. Esteves da Silva 《Journal of Dispersion Science and Technology》2013,34(6):786-791
Synthesis, characterization, and the optical behavior of CdS quantum dots nanoparticles, confined in zeolites, following a new synthesis approach in different natural zeolites mordenite, clinoptilolite, and syntheticZSM-5, were carried out. The composite materials are characterized by x-ray diffraction, Fourier transmission infrared spectroscopy, energy dispersive, scanning and transmission electron microscopy. After CdS-QDs formation, the synthesized materials become fluorescent with emission wavelengths (average and standard deviation of the maximum wavelength; full width of half maximum): Mordenite-CdS QDs (628 ± 5 nm; 272 nm); clinoptilolite-CdS QDs (585 ± 8 nm; 284 nm), and ZSM-5-CdS QDs (579 ± 4 nm; 214 nm). [Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Dispersion Science and Technology to view the free supplemental file.] 相似文献
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Highly luminescent thioglycolic acid-capped CdTe-based core/shell quantum dots (QDs) were synthesized through encapsulating CdTe QDs in various inorganic shells including CdS, ZnS and CdZnS. CdTe/CdS core/shell QDs exhibited a significant redshift of emission peaks (a maximum emission peak of 652 nm for the core/shell QDs and 575 nm for CdTe cores) with increasing shell thickness. In contrast, the redshift of photoluminescence (PL) peak wavelength of CdTe/ZnS QDs was less than 15 nm. The PL peak wavelengths of the core/shell QDs depended strongly on core size and shell thickness. The PL quantum yields (QYs) of the CdTe/CdS core/shell QDs are up to 67 % while that of CdTe/ZnS core/shell QDs is 45 %. A composite CdZnS shell made CdTe cores a high PL QY up to 51 % and broadly adjusted PL spectra (a maximum PL peak wavelength of 664 nm). The epitaxial growth of the shell was confirmed by X-ray powder diffraction analysis and luminescence decay experiments. Because of high PL QYs, tunable PL spectra, and low toxicity from a ZnS surface layer, CdTe/CdZnS core/shell QDs will be great potential for bioapplications. 相似文献
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CdTe/CdS量子点的Ⅰ-Ⅱ型结构转变与荧光性质 总被引:4,自引:0,他引:4
制备了壳层厚度可以精确控制的CdTe/CdS核壳量子点, 利用紫外-可见吸收光谱、光致发光光谱、透射电镜和时间分辨光谱等技术, 分析了CdS壳层厚度对CdTe量子点的荧光量子产率和光谱结构的影响规律. 发现了不同于CdSe/CdS, CdSe/ZnS, CdTe/ZnS等核壳量子点的荧光峰展宽、大幅度红移以及荧光寿命大幅度增加现象. 根据能带的位置关系, 随着CdS厚度的增加, CdTe从Ⅰ型结构逐渐过渡到Ⅱ型核壳结构. 对于Ⅱ型CdTe/CdS核壳量子点, 不仅存在CdTe核区导带电子与价带空穴间的直接复合, 还存在CdS壳层导带电子与CdTe核价带空穴界面处的间接复合, 发光机制的变化导致荧光峰的展宽、明显红移和荧光寿命的增加. 当壳层过厚时, 壳层表面新引入的缺陷会阻碍荧光寿命和量子产率的进一步提高. 相似文献
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Julien Lavie Van Binh Vu Daniel Medina-Lopez Yannick Dappe Thomas Liu Loïc Rondin Jean-Sébastien Lauret Sylvain Latil Stéphane Campidelli 《Helvetica chimica acta》2023,106(6):e202300034
Carbon nanomaterials have attracted the attention of the scientific community for more than 30 years now; first with fullerene, then with nanotubes and now with graphene and graphene related materials. Graphene quantum dots (GQDs) are nanoparticles of graphene that can be synthesized following two approaches, namely top-down and bottom-up methods. The top-down synthesis used harsh chemical and/or physical treatments of macroscopic graphitic materials to obtain nanoparticles, while the second is based on organic chemistry through the synthesis of polycyclic aromatic hydrocarbons exhibiting various sizes and shapes that are perfectly controlled. The main drawback of this approach is related to the low solubility of carbon materials that prevents the synthesis of nanoparticles containing more than few hundreds of sp2 carbon atoms. Here we report on the synthesis of a family of rectangular-shaped graphene quantum dots containing up to 162 sp2 carbon atoms. These graphene quantum dots are not functionalized on their periphery in order to keep the maximum similarity with nanoparticles of pure graphene. We chose water with sodium deoxycholate surfactant to study their dispersion and their optical properties (absorption, photoluminescence and photoluminescence excitation). The electronic structure of the particles and of their aggregates are studied using Tight-Binding (TB). We observe that the larger particles ( GQD 3 and GQD 4 ) present a slightly better dispensability than the smaller ones, probably because the larger GQDs can accommodate more surfactant molecules on each side, which helps to stabilize their dispersion in water. 相似文献
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Vorontsov D. S. Okrepka G. M. Khalavka Yu. B. 《Theoretical and Experimental Chemistry》2019,55(2):110-114
Theoretical and Experimental Chemistry - The photoluminescence and photostability of CdTe/CdS nanoparticles encapsulated in matrices of potassium dihydrogen orthophosphate, potassium bromide,... 相似文献
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柠檬酸稳定的水溶性CdSe和CdSe/CdS量子点的荧光特性 总被引:2,自引:0,他引:2
用柠檬酸(citrate)作为稳定剂合成了尺寸分布集中、荧光性质良好的水溶性CdSe量子点。通过调节合成温度可以调控CdSe量子点的尺寸及相应的最大荧光发射波长。当温度由20 ℃增加到95 ℃时,合成的CdSe量子点的平均尺寸由2.0 nm增加到3.2 nm,相应的荧光发射峰由500 nm红移到570 nm,展现出明显的量子尺寸效应。进一步制备了CdSe/CdS核壳量子点,其荧光量子产率比CdSe增加了5~10倍。系统地研究了S/Se物质的量的比对CdSe/CdS量子点荧光特性的影响,通过XPS证实了CdSe/CdS量子点中CdS壳层的存在。利用红外光谱和核磁共振波谱表征了柠檬酸分子中的羧基和羟基氧原子与CdSe量子点表面的Cd离子的配位作用,进而揭示了柠檬酸分子对水溶性CdSe量子点溶液的稳定作用。 相似文献
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Ziyi Liu Fei Li Yi Luo Ming Li Guanghui Hu Xianjuan Pu Tao Tang Jianfeng Wen Xinyu Li Weitao Li 《Molecules (Basel, Switzerland)》2021,26(13)
High-photoluminescence (PL) graphene quantum dots (GQDs) were synthesized by a simple one-pot hydrothermal process, then separated by dialysis bags of different molecular weights. Four separated GQDs of varying sizes were obtained and displayed different PL intensities. With the decreasing size of separated GQDs, the intensity of the emission peak becomes much stronger. Finally, the GQDs of the smallest size revealed the most energetic PL intensity in four separated GQDs. The PL energy of all the separated GQDs shifted slightly, supported by density functional theory calculations. 相似文献
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以油酸为配体,十八烯为溶剂,采用一步法合成了CdS量子点,研究了反应温度、反应时间和Cd/S的摩尔比对量子点光谱性能的影响.X射线衍射(XRD)和高分辨透射电镜(HRTEM)测试结果表明,所获得的CdS量子点为立方闪锌矿结构,且尺寸分布均一,结晶度高,其较强的带边发光、尖锐的紫外吸收峰以及狭窄的荧光发射峰进一步表明量子... 相似文献
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石墨烯量子点的制备 总被引:1,自引:0,他引:1
作为石墨烯家族的最新一员,石墨烯量子点(GQDs)除了具有石墨烯的优异性能,还因量子限制效应和边界效应而展现出一系列新的特性,因此吸引了化学、物理、材料和生物等各领域科学家的广泛关注。仅近两三年内,关于这种新型零维材料的研究,在实验和理论方面均取得了极大进展。本文主要介绍制备GQDs的两大类方法——自上而下和自下而上的方法。前者包括水热法、电化学法和化学剥离碳纤维法,后者则主要介绍溶液化学法、超声波法和微波法、可控热解多环芳烃法。另外还对一些制备条件较为苛刻的制备方法如电子束刻蚀法和钌催化富勒烯C60开笼法也作了简要介绍,并对GQDs的应用前景进行了展望。 相似文献
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采用溶胶-凝胶法结合气氛控制制备了CuInS2纳米晶玻璃. 利用X射线粉末衍射仪(XRD)和透射电子显微镜(TEM)对CuInS2纳米晶在玻璃中的形貌和微结构进行了表征, 并利用飞秒Z扫描技术对该玻璃的三阶非线性光学性质进行了研究. 结果表明, 在钠硼硅玻璃中形成了尺寸分布为10 nm左右的均一的CuInS2四方晶系纳米晶. 该玻璃体现出优良的三阶非线性光学性能, 其三阶非线性光学折射率γ、吸收系数β和极化率χ(3)分别为8.57×10-16 m2/W, 3.74×10-8 m/W和1.95×10-17 m2/V2. 相似文献
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Sukhendu Nandi Sofiya Kolusheva Ravit Malishev Alexander Trachtenberg T. P. Vinod Raz Jelinek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7755-7759
Graphene quantum dots (GQDs) have attracted considerable interest due to their unique physicochemical properties and various applications. For the first time it is shown that GQDs surface‐functionalized with hydrocarbon chains (i.e., amphiphilic GQDs) self‐assemble into unilamellar spherical vesicles in aqueous solution. The amphiphilic GQD vesicles exhibit multicolor luminescence that can be readily exploited for membrane studies by fluorescence spectroscopy and microscopy. The GQD vesicles were used for microscopic analysis of membrane interactions and disruption by the peptide beta‐amyloid. 相似文献
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在水相中合成高发光性能的CdTe量子点,研究以巯基乙酸(TGA)为稳定剂对CdTe表面进行修饰,制备在水中分散性良好的纳米晶,通过对CdTe量子点合成反应条件的摸索,掌握了其合成的反应规律.同时用紫外分光光度计、荧光分光光度计和透射电子显微镜对其进行了表征.结果表明,回流时间、n(Cd2+):n(HTe-)、反应物浓度、TGA用量、反应体系pH值,对纳米晶的光学性质具有显著影响.回流2 h制得的CdTe纳米粒子直径约为5 nm,其发射峰窄且对称,表现出良好稳定的光学性质. 相似文献
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This minireview describes recent progress in solution‐processable graphene quantum dots (SGQDs). Advances in the preparation, modification, properties, and applications of SGQDs are highlighted in detail. As one of emerging nanostructured materials, possible ongoing research related to the precise control of the lateral size, edge structure and surface functionality; the manipulation and characterization; the relationship between the properties and structure; and interfaces with biological systems of SGQDs have been speculated upon. 相似文献