Francesco Di Stasio  Joel Q. Grim  Vladimir Lesnyak  Prachi Rastogi  Liberato Manna  Iwan Moreels  Roman Krahne 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(11):1328-1334

Core–shell CdSe/CdS nanocrystals are a very promising material for light emitting applications. Their solution‐phase synthesis is based on surface‐stabilizing ligands that make them soluble in organic solvents, like toluene or chloroform. However, solubility of these materials in water provides many advantages, such as additional process routes and easier handling. So far, solubilization of CdSe/CdS nanocrystals in water that avoids detrimental effects on the luminescent properties poses a major challenge. This work demonstrates how core–shell CdSe/CdS quantum dot‐in‐rods can be transferred into water using a ligand exchange method employing mercaptopropionic acid (MPA). Key to maintaining the light‐emitting properties is an enlarged CdS rod diameter, which prevents potential surface defects formed during the ligand exchange from affecting the photophysics of the dot‐in‐rods. Films made from water‐soluble dot‐in‐rods show amplified spontaneous emission (ASE) with a similar threshold (130 μJ/cm²) as the pristine material (115 μJ/cm²). To demonstrate feasibility for lasing applications, self‐assembled microlasers are fabricated via the “coffee‐ring effect” that display single‐mode operation and a very low threshold of ～10 μJ/cm². The performance of these microlasers is enhanced by the small size of MPA ligands, enabling a high packing density of the dot‐in‐rods.  相似文献   

    

Sheng‐Chieh Liao  Yong‐Lun Chen  Wei‐Cheng Kuo  Jeffrey Cheung  Wei‐Cheng Wang  Xuan Cheng  Yi‐Ying Chin  Yu‐Ze Chen  Heng‐Jui Liu  Hong‐Ji Lin  Chien‐Te Chen  Jeng‐Yih Juang  Yu‐Lun Chueh  Valanoor Nagarajan  Ying‐Hao Chu  Chih‐Huang Lai 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(33):4117-4122

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Xiaodong Pi Rong Wang Deren Yang 《材料科学技术学报》2014,30(7):639-643

As a leading surface modification approach,hydrosilylation enables freestanding silicon nanocrystals(Si NCs) to be well dispersed in a desired medium.Although hydrosilylation-induced organic layers at the NC surface may somehow retard the oxidation of Si NCs,oxidation eventually occurs to Si NCs after relatively long time exposure to air.We now investigated the oxidation of hydrosilylated Si NCs in the frame work of density functional theory(DFT).Three oxygen configurations that may be introduced by the oxidation of a Si NC are considered.It is found that a hydrosilylated Si NC is less prone to oxidation than a fully H-passivated Si NC in the point of view of thermodynamics.At the ground state,backbond oxygen(BBO) and hydroxyl(OH) hardly change the gap between the highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO) of a hydrosilylated Si NC.At the excited state,the decrease in the HOMO-LUMO gap induced by the introduction of doubly bonded oxygen(DBO) is more significant than that induced by the introduction of BBO or OH.We have correlated the changes in the optical absorption(emission) of a hydrosilylated Si NC after oxidation to those of the HOMO—LUMO gap at the ground state(excited state).  相似文献   

    

Yi Pan  Niklas Nilius  Christian Stiehler  Hans‐Joachim Freund  Jacek Goniakowski  Claudine Noguera 《Advanced Materials Interfaces》2014,1(9)

Compact CeO₂(111) films grown on Ru(0001) can be transformed into well‐shaped nanoparticles by annealing them in an oxygen‐poor environment. With increasing temperature, the particles undergo a distinct shape evolution that finally leads to crystallites exposing wide (100) facets. The atomic structure of the (100) termination is determined with a combination of high‐resolution scanning tunneling microscopy and density functional theory. Two surface reconstructions are identified that are compatible with the need to compensate for the intrinsic dipole of the (100) plane and with a substantial reduction of the oxide material. Our study provides insights into the rarely explored (100) surface of ceria, which can be considered as model system for studying chemical processes on the polar termination of reducible oxides.  相似文献   

    

Chao Wang  Dongli Meng  Jinhua Sun  Jamil Memon  Yong Huang  Jianxin Geng 《Advanced Materials Interfaces》2014,1(4)

Reduced graphene oxide (RGO) wrapped titanium dioxide nanocrystals (TiO₂ NCs@RGO) with oxygen vacancies (Vo) and Ti³⁺ defects have been synthesized by electrostatically wrapping GO around TiO₂ NCs followed by thermal annealing at 400 °C. Transmission electron microscope observations have shown that TiO₂ NCs@RGO has a unique crystalline core/crystalline shell structure, which is different from the original amorphous TiO₂ covered TiO₂ NCs. Raman spectroscopy, X‐ray photoelectron spectroscopy, and electron paramagnetic resonance have demonstrated that Vo‐Ti³⁺ species are more readily formed in TiO₂ NCs@RGO than in TiO₂ NCs. As a result, TiO₂ NCs@RGO exhibits enhanced optical absorption in a wide wavelength range from visible light to near IR and red‐shifted absorption edge. In the photocatalytic degradation reaction of methyl orange, the photodegradation rate constant for TiO₂ NCs@RGO is 2.4 times higher than that of TiO₂ NCs. The enhanced photocatalytic performance can be attributed to the improved charge separation at the interface of TiO₂ NCs and RGO layer and the enhanced optical absorption in visible light region due to the donor levels of the defects such as Vo‐Ti³⁺ species. This work establishes a new method for preparing Vo defect contained TiO₂ catalysts.  相似文献   

    

Anteneh Belete  Hendrik Metz  Thomas Mueller  Karsten Maeder 《Drug development and industrial pharmacy》2015,41(3):406-414

Background: The interplay between numerous factors, including the size, shape, coating, surface charge and composition of particles is known to affect the pharmacokinetics and biodistribution of superparamagnetic iron oxides (SPIOs). This makes understanding the role of each factor independently quite challenging.

Methods: In the present study, the in vivo magnetic resonance imaging (MRI), biodistribution and hepatic clearance evaluations of two SPIOs Formulations A and B developed from ～13.5?nm hydrophobic oleic acid stabilized monodisperse magnetite nanocrystals core and lipid-based amphiphilic stabilizers were performed using a prototype benchtop MR imager (22?MHz) and pulsed nuclear magnetic resonance (NMR) system (20?MHz), respectively. Formulation A was composed of mPEG-2000-DSPE and Formulation B was composed of Phospholipon-100H, sucrose ester M-1695 and Cremophor RH-40.

Results: The in vivo MRI investigations showed that both formulations were safe and effective as potential liver MR contrast agents with sustained liver contrast for at least seven days. In addition, ex vivo relaxometric investigations revealed that the formulations predominantly distribute to the liver and spleen following I.V. injection. The hepatic clearance kinetics determined based on the relaxometric quantification method indicated that both formulations exhibited a biphasic clearance process with a slow terminal clearance half-life of 11.5 and 12.7 days, respectively, for Formulations A and B.

Conclusions: The results of this study showed the potential biomedical applications of the investigated magnetopharmaceutical formulations as MRI contrast agents.  相似文献   

    

Le He  Michael Janner  Qipeng Lu  Mingsheng Wang  Hua Ma  Yadong Yin 《Advanced materials (Deerfield Beach, Fla.)》2015,27(1):86-92

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Mohamad Insan Nugraha  Roger Häusermann  Hiroyuki Matsui  Mykhailo Sytnyk  Jun Takeya  Maria Antonietta Loi 《Advanced materials (Deerfield Beach, Fla.)》2015,27(12):2107-2112

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Zheng Chen  Dieqing Zhang  Xiaolei Wang  Xilai Jia  Fei Wei  Hexing Li  Yunfeng Lu 《Advanced materials (Deerfield Beach, Fla.)》2012,24(15):2030-2036

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Luana Persano  Andrea Camposeo  Francesca Di Benedetto  Ripalta Stabile  Anna M. Laera  Emanuela Piscopiello  Leander Tapfer  Dario Pisignano 《Advanced materials (Deerfield Beach, Fla.)》2012,24(39):5319-5319

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