基于AuCl(油胺)复合物合成形貌可控的金纳米结构

简要综述了使用一价金复合物AuCl(油胺)作为前驱物合成形貌可控的金纳米结构的相关工作. 通过改变有机溶剂、添加异质金属纳米粒子及控制反应温度等手段, 成功合成出球形的金纳米粒子(平均直径12.7 nm)、超细金纳米线(平均直径1.8 nm)及超细金纳米棒(平均直径2 nm); 并通过牺牲磁性纳米粒子模板的方法合成出枝状金纳米结构. 除了对合成方法和过程的介绍, 还简要讨论了每种纳米结构的形成机制.     

油胺/油酸稳定的CdSe量子点的绿色合成

以液体石蜡为高温反应溶剂,油酸和油胺为混合稳定剂,利用高温热解法一步合成了高质量的CdSe量子点。通过紫外-可见吸收光谱、荧光发射光谱、红外光谱和X射线衍射等手段对量子点的光学性质和结构进行了表征。结果表明,油胺/油酸混合表面活性剂稳定的量子点吸收光谱峰形更尖锐,荧光发射光谱半峰宽更窄。反应温度和反应时间均对量子点的生长过程和光学性质有明显影响,220℃下反应15 min,荧光量子产率可达26%。得到的CdSe量子点为立方晶型,表面同时包覆了油酸和油胺,具有良好的光稳定性。该方法无需使用三烷基膦,价廉环保,且合成的CdSe量子点性质稳定、性能优越,有利于其在分析检测领域中的应用。     

Silver-Alkylamine Complex Mediated Single Micelle toward Synthesis of Sub-8 nm Silver Nanocrystals

Small size and narrow distribution are the key factors to improve performances of metal nanocrystals due to nanosize effect. Here, a silver-alkylamine complex–mediated single micelle, a one-pot approach, for controlled synthesis of monodisperse silver nanocrystals, in which oleylamine molecules play key roles serving both as complex agent and as micellar coalescence blocker is reported. After the synthesis, monodisperse products can be directly collected through subsequent single-step separation as the particle size is finely adjusted during the synthesis. Dual-soluble silver oleylamine complex is prepared through liquid phase complexing and is used as oil-soluble precursor in single reverse micelle. The as-synthesized silver nanocrystals are very uniform with a controlled size of 6.00 ± 0.29 or 8.0 ± 0.40 nm and a narrow size distribution with a standard deviation (σ) of ≈5.0%. The protocol offers a general platform for fast synthesis of noble metal nanocrystals with rationally designed size and structure.     

Effects of Capping Agents on the Oxygen Reduction Reaction Activity and Shape Stability of Pt Nanocubes

We investigated the formation of Pt nanocubes (NCs) and their electrocatalytic oxygen reduction reaction (ORR) properties and structural stability using two different capping agents, namely, polyvinylpyrrolidone (PVP) and oleylamine (OAm). The mono-dispersity of the obtained Pt NCs and their interactions with PVP and OAm were analyzed by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Fourier-transformed infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The TEM data show a high mono-dispersity (82 %) and a large mean particle size (9-10 nm) for the Pt NCs obtained by the oleylamine-assisted method compared to those prepared via the PVP-assisted procedure (68 %, 6–7 nm). FTIR, XPS, and TGA data show that PVP and OAm still remain at the Pt surface, despite washing. Interestingly, the OAm-capped Pt NCs show significantly higher electrochemically active surface area (ECSA) and ORR activity than the PVP-capped ones. An accelerated stress protocol, however, reveals that the OAm-capped NCs possess a poor structural stability during electrochemical cycling. The loss of a defined surface arrangement in the NCs is connected with a transformation into a near-spherical particle shape. In contrast, the PVP-capped NCs mainly retain their particle shape due to their strong capping behavior. In addition, we have developed a degradation model for NCs as a function of electrochemical parameters such as upper potential and cycle number. Altogether, we provide fundamental insights into the electronic interactions between capping agent and Pt NCs and the role of the adsorption strength of the capping agent in improving the electrochemical ORR performance as well as the structural stability of shape-controlled nanoparticles.     

The role of oxidative etching in the synthesis of ultrathin single-crystalline Au nanowires

The fabrication of ultrathin single-crystal Au nanowires with high aspect ratio and that are stable in air is challenging. Recently, a simple wet-chemical approach using oleylamine has been reported for the synthesis of Au nanowires with micrometer length and 2 nm in diameter. Despite efforts to understand the mechanism of the reaction, an ultimate question about the role of oxygen (O(2)) during the synthesis remained unclear. Here we report that the synthesis of ultrathin Au nanowires employing oleylamine is strongly affected by the amount of O(2) absorbed in the reaction solution. Saturating the solution with O(2) leads to both a high-yield production of nanowires and an increase in their length. Nanowires with diameters of about 2 nm and lengths of 8 μm, which corresponds to an aspect ratio of approximately 4000, were produced. The role of oxygen is attributed to the enhanced oxidation of twin defects on Au nanoparticles formed in the first stage of the reaction. Understanding the role of oxidative etching is crucial to significantly increasing the yield and the length of ultrathin Au nanowires.     

表面配体调控的CH3NH3PbBr3纳米片的聚集自组装

采用热注入的方法合成了CH3NH3Pb Br3纳米片,荧光光谱分析发现稀释一定的倍数会使荧光光谱由451 nm红移到531nm。TEM及XRD分析表明,发光红移是由CH3NH3Pb Br3纳米片聚集自组装导致的颗粒变大引起的。进一步的对比实验表明,油胺在纳米片聚集自组装的过程中起到了至关重要的作用,由此结合XRD和TEM表征,阐述了CH3NH3Pb Br3纳米片聚集自组装的机理。     

Versatile Tri(pyrazolyl)phosphanes as Phosphorus Precursors for the Synthesis of Highly Emitting InP/ZnS Quantum Dots

Tri(pyrazolyl)phosphanes ( 5 ^R1,R2) are utilized as an alternative, cheap and low‐toxic phosphorus source for the convenient synthesis of InP/ZnS quantum dots (QDs). From these precursors, remarkably long‐term stable stock solutions (>6 months) of P(OLA)₃ (OLAH=oleylamine) are generated from which the respective pyrazoles are conveniently recovered. P(OLA)₃ acts simultaneously as phosphorus source and reducing agent in the synthesis of highly emitting InP/ZnS core/shell QDs. These QDs are characterized by a spectral range between 530–620 nm and photoluminescence quantum yields (PL QYs) between 51–62 %. A proof‐of‐concept white light‐emitting diode (LED) applying the InP/ZnS QDs as a color‐conversion layer was built to demonstrate their applicability and processibility.     

Voltammetric determination of electronic structure of quantum dots

Electronic structure plays an important role in determining the physiochemical properties of semiconductor quantum dots (QDs). Fabrication of high-performance QD devices relies on the reliable determination of electronic structure of QDs. Voltammetry enables the easily accessible detection on the energy levels of QDs. Herein, the fundamentals of voltammetric detection are first reviewed and discussed. Since the common ways used for tailoring electronic structure of QDs include tuning size, surface engineering, and varying composition, we next summarize the recent research on using voltammetry for probing the energy levels when studying these three effects.     

Nanofluorides

The present review article covers major aspects of inorganic chemistry of nanofluorides, including methods of their synthesis (thermolysis of the precursors, co-precipitation from solutions, reversed micelle technique, hydro- and solvo-thermal techniques, sol–gel method, etc.), nanochemical effects (enhanced chemical activity, self-organization and self-assembly, non-classical mechanism of the single crystal growth, synthesis of non-equilibrium phases), targeted preparation of 1D, 2D, and 3D nanostructures, surface modification of the nanoparticles, fluoride nanocomposites (glass- and nano-ceramics) as well as applications of nanofluorides.     

Thermal Study of Surfactant and Anion Adsorption on Clinoptilolite

The mechanism of surfactant adsorption on various forms of clinoptilolite was studied by DTA, TG and DTG analyses. The examined series of surfactant modified clinoptilolite (SMC) was previously prepared by the adsorption of the surface-active oleylamine on Ca²⁺, Na⁺, H⁺ and mechanochemically treated forms of clinoptilolite. The oleylamine was most strongly adsorbed on H⁺-forms of clinoptilolite due to the largest number and strength of adsorption sites. The surfactant adsorption mechanism on H⁺-form of clinoptilolite was studied by recording the series of variously surfactant-loaded samples. The products of sulphate, dihydrogenphosphate and hydrogenchromate adsorption on SMC were analyzed by DTA, TG and DTG in order to investigate the mechanism of anion adsorption.This revised version was published online in November 2005 with corrections to the Cover Date.