Nanomaterials for electrochemical energy storage

The development of nanotechnology in the past two decades has generated great capability of controlling materials at the nanometer scale and has enabled exciting opportunities to design materials with desirable electronic, ionic, photonic, and mechanical properties. This development has also contributed to tile advance in energy storage, which is a critical technology in this century. In this article, we will review how the rational design of nanostructured materials has addressed the challenges of batteries and electrochemical capacitors and led to high-performance electrochemical energy storage devices. Four specific material systems will be discussed： i） nanostructured alloy anodes for Li-batteries, ii） nanostructured sulfur cathodes for Li-batteries, iii） nanoporous open- framework battery electrodes, and iv） nanostructured electrodes for electrochemical capacitors.     

微纳米加工技术在纳米物理与器件研究中的应用

物质在纳米尺度下可能呈现出与体材料不同的物理特件，这正是纳米科技发展的基础之一。要想探索在纳米尺度下材料物埋性质的变化规律及可能的应用领域，离不开相应的技术手段，微纳米加工技术作为当今高技术发展的重要技术领域之一，是实现功能人工纳米结构与器件微纳米化的基础。本文根据几个不同的应用领域，介绍了微纳米加工技术在纳米物理与器件研究领域的应用。     

Superhydrophobicity of polyvinylidene fluoride membrane fabricated by chemical vapor deposition from solution

Due to the chemical stability and flexibility, polyvinylidene fluoride (PVDF) membranes are widely used as the topcoat of architectural membrane structures, roof materials of vehicle, tent fabrics, and so on. Further modified PVDF membrane with superhydrophobic property may be even superior as the coating layer surface. The lotus flower is always considered to be a sacred plant, which can protect itself against water, dirt, and dust. The superhydrophobic surface of lotus leaf is rough, showing the micro- and nanometer scale morphology. In this work, the microreliefs of lotus leaf were mimicked using PVDF membrane and the nanometer scale peaks on the top of the microreliefs were obtained by the method of chemical vapor deposition from solution. The surface morphology of PVDF membrane was investigated by scanning electronic microscopy (SEM) and atomic force microscope (AFM). Elemental composition analysis by X-ray photoelectron spectroscopy (XPS) revealed that the material of the nanostructure of PVDF membrane was polymethylsiloxane. On the lotus-leaf-like PVDF membrane, the water contact angle and sliding angle were 155° and 4°, respectively, exhibiting superhydrophobic property.     

纳米材料科学中的谱学研究

谱学分析方法是研究纳米体系结构和性能3的重要手段之一，对纳米材料进行深入研究离不开各种谱学方法的表征，本文综述了常用的谱学方法，如紫外可见光谱，红外光谱，拉曼光谱，穆斯堡尔谱，正电子湮没及光声光谱等在纳米材料研究中的最新进展，结合典型实例，对各种谱学方法的原理，特点以及在纳米体系研究中所能提供的重要信息进行了归纳和分析，展望了谱学分析方法在纳米科技研究中进一步的应用前景，以及在纳米材料研究中建立纳米尺度分辨的谱学检测方法和发展新的谱学技术等重要的发展方向。     

表面等离子体激元纳米激光器技术及应用研究进展

传统半导体激光器由于采用光学系统反馈而存在衍射极限,其腔长至少是其发射波长的一半,因此难以实现微小化。基于表面等离子体激元的纳米激光器可以实现深亚波长乃至纳米尺度的激光发射,而且现代微纳加工技术的逐步成熟,也为亚波长乃至纳米量级激光器的研制提供了成熟的技术条件。本文重点综述了国际上已成功实验验证的基于表面等离子体激元的纳米激光器的最新研究进展,综述了表面等离子体激元的基本原理,给出了若干种表面等离子体激元纳米激光器的结构和特点,指出该类激光器现存问题主要表现在激元损耗高及由此引起的制备工艺和电泵浦涉及的技术难题。文中最后展望了纳米激光器的应用和研究前景。     

Morphologies and optical properties of poly(2,5-diethoxyphenylene) nanofibril arrays

An anodic aluminum oxide (AAO) membrane can be used as a template for the synthesis of nanostructures. In this paper, we have fabricated poly(2,5-diethoxyphenylene) (EtO-PPP) nanofibril arrays by oxidative coupling polymerization of 1,4-diethoxybenzene (DEB) within the pores of an AAO template. The detailed molecular structure of the polymer nanofibrils was characterized by using the infrared spectrum and the ¹H-NMR spectrum. We have used transmission electron microscopy, scanning electron microscopy, and atomic force microscopy to confirm the morphologies and images of the template and the fabricated nanometer scale of poly(2,5-diethoxyphenylene)nanofibril arrays. The experimental results demonstrate that the pores of the AAO membrane are regular and uniform, and parallel to each other. Furthermore, the EtO-PPP chains in the narrowest template-synthesized fibrils were oriented parallel to the pore axes of the AAO membrane, and perpendicular to the surface of the aluminum substrate. The polymer chain orientation is partially responsible for the enhanced conductivity. The ultraviolet absorption maximum shows that the polymer contains a better extended π-conjugation system along the poly(p-phenylene) backbone, which results in a longer-wavelength shift of the absorption band. The photoluminescence (PL) spectrum of nanofibril arrays exhibits a 5-nm blue shift of the emission in comparison with the unordered molecules. Received: 3 January 2002 / Accepted: 7 January 2002 / Published online: 17 December 2002 RID="*" ID="*"Corresponding author. Fax: +86-931/891-1100, E-mail: lihl@lzu.edu.cn     

Mechanics and Friction at the Nanometer Scale

In this overview, we will give an introduction to experiments in which manipulation is used a means of uncovering the intrinsic response and dynamical behavior of small objects. Experiments done on individual particles reveal new and rich behaviors that are inaccessible to averaging methods. Experiments exploring the stiffness and toughness of carbon nanotubes will be presented showing that nanometer scale engineered materials can far outperform current engineering materials. Through AFM manipulation, imaging and force measurements, the stiffness of this material was found to equal or exceed diamond. Their toughness is also extraordinary. Due to their near crystalline perfection, carbon nanotubes are able to undergo strains exceeding 15% during bending without damage. Through AFM manipulation experiments, these large deformations have been shown to be highly reversible. Experiments in which the lateral force of manipulation of small objects across surfaces is measured show that friction at the nanometer scale occurs without wear processes and is an intrinsic property of the particular interface. Results are also presented showing anisotropic behavior in friction and movement due to commensurate lattice effects. At the nanometer scale, the contacting surfaces can be nearly perfect so that commensurate effects are not partially averaged out by many differently oriented domains. It has been shown that friction can very over an order of magnitude depending on the relative orientation of the contacting surfaces. The relative orientation of object and substrate lattices also can determine the modes of motion. In some cases the particle is confined to move in one direction. In other cases the relative orientation determines whether the particle rolls, rotates in-plane or slides. These effects may have implications on the fundamental mechanisms of friction. They provide a laboratory for testing different geometrical configurations of atoms sliding on atoms. The results may also have implications in the design of nanometer scale electromechanical mechanisms.     

Raman spectroscopy of graphene and carbon nanotubes

This paper reviews progress that has been made in the use of Raman spectroscopy to study graphene and carbon nanotubes. These are two nanostructured forms of sp² carbon materials that are of major current interest. These nanostructured materials have attracted particular attention because of their simplicity, small physical size and the exciting new science they have introduced. This review focuses on each of these materials systems individually and comparatively as prototype examples of nanostructured materials. In particular, this paper discusses the power of Raman spectroscopy as a probe and a characterization tool for sp² carbon materials, with particular emphasis given to the field of photophysics. Some coverage is also given to the close relatives of these sp² carbon materials, namely graphite, a three-dimensional (3D) material based on the AB stacking of individual graphene layers, and carbon nanoribbons, which are one-dimensional (1D) planar structures, where the width of the ribbon is on the nanometer length scale. Carbon nanoribbons differ from carbon nanotubes is that nanoribbons have edges, whereas nanotubes have terminations only at their two ends.     

Electrospun composite nanofibers for functional applications

In this article an outline of studies conducted to date utilizing the process of electrospinning is presented. This overview for the first time focuses on research of composite nanofiber synthesis and their applications. The phenomenon of bringing materials to the nanometer scale not only improves their properties, but also creates entirely new ones. The electrospinning technique is a simple and versatile method that offers a time and cost effective production of strategic combinations of polymer and composites nanofibers useful for numerous applications highlighted in this review. The future prospects of the field are also examined.     

Pore dynamics in lipid membranes

Transient circular pores can open in plasma membrane of cells due to mechanical stress, and failure to repair such pores lead to cell death. Similar pores in the form of defects also exist among smectic membranes, such as in myelin sheaths or mitochondrial membranes. The formation and growth of membrane defects are associated with diseases, for example multiple sclerosis. A deeper understanding of membrane pore dynamics can provide a more refined picture of membrane integrity-related disease development, and possibly also treatment options and strategies. Pore dynamics is also of great importance regarding healthcare applications such as drug delivery, gene or as recently been implied, cancer therapy. The dynamics of pores significantly differ in stacks which are confined in 2D compared to those in cells or vesicles. In this short review, we will summarize the dynamics of different types of pores that can be observed in biological membranes, which include circular transient, fusion and hemi-fusion pores. We will dedicate a section to floral and fractal pores which were discovered a few years ago and have highly peculiar characteristics. Finally, we will discuss the repair mechanisms of large area pores in conjunction with the current cell membrane repair hypotheses.     

Nanometer Scale Electrical Characterization of Artificial Mesostructures

In this article, we review advances in experimental techniques for the electrical characterization of artificial mesostructures from nanometer to micrometer size. As the scale of electronic devices is rapidly approaching the 100-nm benchmark, new tools are becoming necessary to study and characterize them. We are also at a point where new tools to fabricate these devices are becoming increasingly relevant. We discuss the various characterization techniques applicable to objects of this scale, with particular emphasis on scanned probe methods.     

DNA折纸结构介导的多尺度纳米结构精准制造

原子及近原子尺度制造在近年来一直是物质科学领域被广泛探讨的前沿问题.当制造和加工的尺度从微米、纳米逐渐走向原子级别时,材料在常规尺度下所具备的性质已无法通过经典理论进行解释,相反地,会在这一尺度下展现出一系列新奇的特性.因而对材料极限制造尺度和颠覆性物性的不断追求始终是科学界共同关注的重点领域.作为一种在纳米尺度下对结构制造单元进行精细操控的先进手段,DNA纳米技术的开发和发展为纳米制造甚至原子制造提供了新的观点和思路,而DNA折纸术作为DNA纳米技术的重要组成部分,正在凭借其在结构制造过程当中的高度可编程性成为纳米尺度下进行各类物质精准制造的独特的解决方案,并可能为不同物质不同材料更小尺度和任意形状的精准构筑带来机遇.本文首先简单概述了DNA折纸术的基本原理和发展历程,然后根据制造策略的不同对DNA折纸结构的纳米制造的相关代表性工作做了总结,并在文末提出了对于DNA折纸结构在原子制造中的可行性的思考和未来发展方向的展望.     

碳纳米管材料及应用

碳纳米管自发现以来，由于其独特的结构和奇特的物理，化学和力学特性以及其潜在的应用前景而倍受人们的关注。本文介绍近年来这一前沿研究领域所取得的部分重要研究进展，并讨论碳纳米管的几种应用前景。     

Influence of colloidal templates on the impedance spectroscopic behaviour of Pr0.7Sr0.3Fe0.8Ni0.2O3 for solid oxide fuel cell applications

The creation of porous materials with three-dimensional periodicity has been identified as being of potential interest for increasing the overall performance of solid oxide fuel cells (SOFC). In this work, we have investigated the formation of pore systems in the nanometer scale by replicating colloidal templates. Templating methods have been used to prepare iron-nickel-based perovskite Pr_0.7Sr_0.3Fe_0.8Ni_0.2O₃ material with nanoporous microstructure. Polymethyl methacrylate (PMMA), polystyrene (PS) and polycarboxylate (PC) microspheres with different diameters were used as pore formers. These samples were synthesized and characterized by thermogravimetric analysis, inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction, transmission electron microscopy and field emission scanning electron microscopy. The polarization resistance of the materials was studied by Electrochemical Impedance Spectroscopy. The study demonstrated that templated porosity is maintained and highly influences on the impedance spectroscopic behaviour, being the material synthesized with policarboxylate microspheres the most interesting of the three used templates for SOFC applications.     

Material transport in dip-pen nanolithography

Dip-pen na.nolithography （DPN） is a useful method for directly printing materials on surfaces with sub-50nm resolution. Because it, involves the physical transport of materials from a scanning probe tip to a surface and the subsequent chemical interaction of that material with the surface, there are many factors to consider when attempting to understand DPN. In this review, we overview the physical and chemical processes that are known to play a role in DPN, Through a detailed review of the literature, we classify inks into three general categories based on their transport properties, and highlight the myriad ways that. DPN can be used to perform chemistry at the tip of a scanning probe.     

Optical properties of (nanometer MCM-41)-(malachite green) composite materials

Nanosized materials loaded with organic dyes are of interest with respect to novel optical applications. The optical properties of malachite green (MG) in MCM-41 are considerably influenced by the limited nanoporous channels of nanometer MCM-41. Nanometer MCM-41 was synthesized by tetraethyl orthosilicate (TEOS) as the source of silica and cetyltrimethylammonium bromide (CTMAB) as the template. The liquid-phase grafting method has been employed for incorporation of the malachite green molecules into the channels of nanometer MCM-41. A comparative study has been carried out on the adsorption of the malachite green into modified MCM-41 and unmodified MCM-41. The modified MCM-41 was synthesized using a silylation reagent, trimethychlorosilane (TMSCl), which functionalized the surface of nanometer MCM-41 for proper host-guest interaction. The prepared (nanometer MCM-41)-MG samples have been studied by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, low-temperature nitrogen adsorption-desorption technique at 77 K, Raman spectra and luminescence studies. In the prepared (nanometer MCM-41)-MG composite materials, the frameworks of the host molecular sieve were kept intact and the MG located inside the pores of MCM-41. Compared with the MG, it is found that the prepared composite materials perform a considerable luminescence. The excitation and emission spectra of MG in both modified MCM-41 and unmodified MCM-41 were examined to explore the structural effects on the optical properties of MG. The results of luminescence spectra indicated that the MG molecules existed in monomer form within MCM-41. However, the luminescent intensity of MG incorporated in the modified MCM-41 are higher than that of MG encapsulated in unmodified MCM-41, which may be due to the anchored methyl groups on the channels of the nanometer MCM-41 and the strong host-guest interactions. The steric effect from the pore size of the host materials is significant. Raman spectra firmly demonstrated the stable form obtained after the MG incorporation into the nanometer MCM-41. Therefore, nanometer MCM-41 appears to have a good potential for its use as a support for dyes and the (nanometer MCM-41)-MG composite materials may give a wide optical application.     

纳米级自旋电子学材料取得重要进展

因为纳米级的自旋电子学器件需要在纳米尺度上仍能在较高温度下保持优异性能的高自旋极化率材料，故与半导体相容的半金属铁磁体近来受到高度重视．文章介绍作者在这个方向上研究工作的最新重要进展：通过大规模系统的高精度第一原理计算，作者发现三个3d过渡金属硫系化合物的闪锌矿相具有优异的半金属铁磁性，并且其结构性能适合做成具有足够厚度的薄膜或层状材料，便于应用于纳米级自旋电子学器件。     

Fluorescence lifetime distributions in membrane systems

Membranes are complex biological systems that display heterogeneity at all spatial scales. At a molecular level, the heterogeneity arises from lipid and protein composition. At the cellular level, heterogeneity is due to membrane organization and large scale morphology. A quantitative evaluation of membrane heterogeneity at a microscopic level is very important for several fields of membrane studies. We have developed a method for the analysis of the decay of fluorescent membrane probes that can provide a quantity sensitive to membrane heterogeneity. This method is based on the analysis of the fluorescence decay using continuous lifetime distributions. The major challenge in the interpretation of the analysis results is in the identification, at a molecular level, of the mechanisms that influence the fluorescence decay. In this review we illustrate the principles of data analysis and we show examples of identification of the measured parameters with specific variables that affect membrane heterogeneity.     

Towards X-ray induced transient grating methods for nanometer scale dynamics: Diffraction on transient structures induced by extreme ultraviolet radiation from FLASH

Using the high brilliance femtosecond soft X-ray pulses from the Free-Electron LASer at Hamburg (FLASH) the X-ray induced transient optical reflectivity change of GaAs has been established as a versatile method for femtosecond X-ray/optical cross-correlation [1]. As the underlying physical mechanism is the X-ray induced dynamics within solids, we present in this work a feasibility study how transient grating methods could be used to study nanometer scale dynamics in materials, such as the radical diffusion parameters in photoresist materials for EUV lithography.     

Quantum size effect of electron density in ultra-thin metal films and its influence on the interlayer relaxation

Further minimization of electronic devices and microelectromechanical systems (MEMS) requires the feature sizes of relevant materials to be shrunk significantly. In such a case, boundary effects, such as interfaces and surfaces, become remarkable, especially in nanometer scale, which must affect their microstructures and properties. In this work, we have analyzed the distribution of electron charge density in Cu and Al ultra-thin films using free electron model. The results show that an electrostatic field may come into being due to quantum size effect, and the interlayer separations must relax to decrease the Coulomb energy, the thinner the films, the larger the relaxation. More interestingly, two opposite deviating directions of the center of negative charges result in two absolutely distinct interlayer relaxations: inwards for Cu and outwards for Al.