Au–Pd Alloy Gradients Prepared by Laterally Controlled Template Synthesis

Lateral control of template synthesis in nanoporous alumina membranes (NAMs) was previously shown by us to enable preparation of graded composite materials. Formation of thickness gradients of Cu was demonstrated using electrodeposition (or electrodissolution) of Cu in the NAM template under a lateral voltage drop applied to the working electrode. This approach is extended here to the formation of compositional gradients. The latter are achieved by electrochemical co‐deposition of two metals (Au and Pd) in the membrane pores from a mixed metal‐ion solution under a lateral potential drop, to form an alloy that shows a continuous lateral change of the Au/Pd ratio. Environmental scanning electron microscopy images of cross sections along the line of the applied voltage gradient show that the deposit height changes gradually, while local elemental analysis by energy dispersive spectrometry and X‐ray diffraction measurements confirm a continuous change of the alloy composition along the membrane matrix.     

Inorganic Macroporous Films from Preformed Nanoparticles and Membrane Templates: Synthesis and Investigation of Photocatalytic and Photoelectrochemical Properties

Colloidal dispersions of titania, zirconia, tin oxide, indium oxide, and ceria have been successfully used to impregnate membrane templates and form the respective metal oxide (MO) porous films. The use of alumina and iron oxide sols in the same procedure, however, resulted in compact structures. By mixing different nanoparticle solutions before impregnation, final inorganic films containing two metal oxides, of variable metal oxide ratios, were obtained. The porous inorganic materials were analyzed in terms of surface area, pore size, film thickness, and crystallinity. The mechanism of nanoparticle infiltration and particle adsorption to the template walls is proposed based on the stability of the inorganic film and a study of the influence of either the sol concentration or washing times on the amount of inorganic substance incorporated in the hybrid material. The photocatalytic decomposition of an organic pollutant, 2‐chlorophenol, was demonstrated for the porous titania material along with the structures containing mixtures of titania with zirconia, indium oxide, and tin oxide. A ratio of 9:1 TiO₂/MO gave the highest photocatalytic activity, which was higher than the activity of Degussa P25 for the TiO₂/In₂O₃ and TiO₂/SnO₂ systems under the same conditions. The titania films have also been attached to substrates—glass or indium tin oxide (ITO) surfaces—and the photoelectrochemical properties of the porous film attained. A comparison with a spin‐coated titania film (prepared from the same colloidal dispersion) showed that the structured porous inorganic film has two times the photoelectrochemical efficiency as the spin‐coated film.     

Formation of Polyaniline Nanorod/Liquid Crystalline Epoxy Composite Nanowires Using a Temperature‐Gradient Method

Liquid crystalline epoxy/polyaniline (LCE/PANI) composite nanowires have been fabricated using an anodic aluminum oxide (AAO) membrane by a temperature‐gradient curing process. PANI nanorods with an average diameter of 30 nm have been synthesized by dispersion polymerization in order to employ them as a curing agent for LCE and as a reinforcement filler for the LCE/PANI composite nanowires. Differential scanning calorimetry and Fourier‐transform infrared spectroscopy indicate that the LCE crosslinking reaction occurred inside the channels of the AAO membrane via the curing of LCE with PANI nanorods. The LCE/PANI composite nanowires exhibit an enhanced electrical conductivity and thermal stability, comparable with a LCE/PANI composite monolith. In addition, these polymer‐composite nanowires also display the characteristics of a functionally gradient conducting material.     

脉冲激光沉积法制备ZnO薄膜的研究进展

基于氧化锌薄膜紫外光发光的实现,ZnO薄膜成为新的研究热点。综述了各种沉积条件对脉冲激光沉积(PLD)技术生长的氧化锌薄膜的微结构、光学和电学性质的影响,ZnO薄膜的厚度在超过400 nm时,呈现出了近似块状的性质。采用PLD技术,可以在适当的条件下制备具有特定功能的氧化锌薄膜。     

SBT铁电薄膜及其脉冲准分子激光制备

采用脉冲准分子激光沉积法在Ｐｔ／Ｔｉ／ＳｉＯ２／Ｓｉ衬底上成功地制备了ＳＢＴ铁电薄膜，发现存在一个最佳沉积衬底温度约为４５０℃。在该温度下沉积的ＳＢＴ薄膜具有较饱和的方形电滞回线，其剩余极化Ｐｒ和矫顽电场Ｅｃ分别为８．４μＣ／ｃｍ２和５７ｋＶ／ｃｍ。     

Recent Advances in ZnO Films Prepared by Pulsed Laser Deposition

Pulsed laser deposition （PLD） is emerging as the most rapid and efficient technique for fabricating the many compound films. ZnO thin films can be prepared under various deposition conditions by PLD. The effects of various substrate temperature, oxygen partial pressure, annealing temperature, substrate, buffer layers thickness and film thickness on micro-structural, optical and electrical properties of ZnO films grown by PLD technology are reviewed. ZnO films with special function can grow under proper conditions by PLD.     

脉冲准分子激光沉积AlN薄膜的研究

采用ArF脉冲准分子激光沉积法并结合退火后处理工艺,在Si（111）衬底上成功地制备了AIN晶态薄膜。X射线衍射、扩展电阻与原子力显微镜等测试结果表明：薄膜具有（101）取向,平均晶粒大小为200nm;薄膜介电性能优异,扩展电阻在108Ω以上。     

脉冲激光沉积制备c轴取向AlN薄膜

ｃ轴取的ＡｌＮ具有优异的压电性和声表面波传输特性,已受到人们日益广泛的重视。文章报道了采用ＫｒＦ脉冲准分子激光沉积工艺,在Ｓｉ（１００）衬底上成功地制备了ｃ轴取向的ＡｌＮ晶态薄膜。Ｘ射拇衍射与傅里叶变换红外光谱的结果表明,在３００℃－８００℃衬底温度下,薄膜均只有（００２）－一个衍射峰,但随着温度的升高,薄膜的结晶质量变好;     

ArF准分子激光立方氮化硼薄膜的制备

采用ＡｒＦ准分子脉冲激光沉积方法（ＰＬＤ），以六方氮化硼（ｈ－ＢＮ）作靶在Ｓｉ（１００）衬底上制备氮化硼薄膜。ＸＲＤ及ＦＴＩＲ透射谱测量表明生成的氮化硼薄膜是含有少量六方氮化硼结构的立方氮化硼（Ｃ－ＢＮ）．ＡＥＳ测量表明不同条件下生成的薄膜中Ｎ与Ｂ的相对含量是不同的，最大比例近乎为１：１，薄膜的维氏显微硬度ＨＶ最大值为１５８０ｋｇ／ｍｍ２。     

CO2 Capture by As‐Prepared SBA‐15 with an Occluded Organic Template

A novel CO₂ capture phenomenon is observed by modifying as‐prepared mesoporous silica SBA‐15 (SBA(P)) with tetraethylenepentamine (TEPA), not only conserving the energy and time required for removing the template, but also opening the way to utilizing the micelle for dispersing guest species. The TEPA species dispersed within the channels of SBA(P) are highly accessible to CO₂ molecules; moreover, the hydroxyl group of the poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (Pluronic P123) template is able to modify the interactions between CO₂ and the amine to enhance the adsorptive capacity of this system. The remarkably high adsorption capacity (173 mg g^–1) of this mesoporous silica–amine composite suggests potential CO₂ trapping applications, especially at low CO₂ concentrations during prolonged cyclic operations.     

Two‐Dimensionally Ordered Copper Grid Patterns Prepared via Electroless Deposition Using a Colloidal‐Crystal Film as the Template

Two‐dimensionally ordered copper grid patterns with different pore sizes and thickness have been fabricated via electroless copper deposition using a colloidal‐crystal film as the template. The pore size of the grid can be adjusted by altering the deposition time. The copper films, with thicknesses of ≈ 100–130 nm and pore sizes of ≈ 100 nm, are flexible and can be peeled off a silicon wafer and rolled up into a reel. Three‐dimensionally ordered porous copper materials have also been prepared using a similar method.     

Assembly of Gold Nanoparticles in a Rod‐Like Fashion Using Proteins as Templates

An area of considerable current interest is the development of a practical approach for assembling inorganic nanoparticles into well‐defined arrays because such a technique would offer immense opportunities leading to applications in microimaging, optoelectronics, therapeutics, etc. This paper illustrates a new, simple one‐step process in which proteins act as templates to assemble gold nanoparticles in a shape‐selective fashion. We show, for the first time, that antibodies to vascular endothelial growth factor 165 isoform, 2C3, and epidermal growth factor receptor can act as templates when present in solution during the synthesis of gold nanoparticles. These proteins direct the assembly of the gold nanoparticles into rod‐like shapes when cooled to –20 °C followed by thawing at room temperature. Immunoglobulin G and bovine serum albumin can also direct the assembly process in a similar fashion; however, small molecules, such as poly(L ‐lysine) and lysine, cannot. The formation of a self‐assembled structure in the form of a continuous rod, or the assembly of discrete nanoparticles in a rod‐like fashion, can be tailored by controlling the ratio of the precursor gold salt, HAuCl₄, to the antibody/protein used as the template. The nanoconjugates are characterized using UV‐vis spectroscopy, transmission electron microscopy, and infrared spectroscopy. The nano‐bioconjugates obtained via this process may find wide application in areas ranging from optoelectronics and biosensors to therapeutics in neoplastic disorders.     

Synthesis and Rate Performance of Monolithic Macroporous Carbon Electrodes for Lithium‐Ion Secondary Batteries

Three‐dimensionally ordered macroporous (3DOM) materials are composed of well‐interconnected pore and wall structures with wall thicknesses of a few tens of nanometers. These characteristics can be applied to enhance the rate performance of lithium‐ion secondary batteries. 3DOM monoliths of hard carbon have been synthesized via a resorcinol‐formaldehyde sol–gel process using poly(methyl methacrylate) colloidal‐crystal templates, and the rate performance of 3DOM carbon electrodes for lithium‐ion secondary batteries has been evaluated. The advantages of monolithic 3DOM carbon electrodes are: 1) solid‐state diffusion lengths for lithium ions of the order of a few tens of nanometers, 2) a large number of active sites for charge‐transfer reactions because of the material's high surface area, 3) reasonable electrical conductivity of 3DOM carbon due to a well‐interconnected wall structure, 4) high ionic conductivity of the electrolyte within the 3DOM carbon matrix, and 5) no need for a binder and/or a conducting agent. These factors lead to significantly improved rate performance compared to a similar but non‐templated carbon electrode and compared to an electrode prepared from spherical carbon with binder. To increase the energy density of 3DOM carbon, tin oxide nanoparticles have been coated on the surface of 3DOM carbon by thermal decomposition of tin sulfate, because the specific capacity of tin oxide is larger than that of carbon. The initial specific capacity of SnO₂‐coated 3DOM carbon increases compared to that of 3DOM carbon, resulting in a higher energy density of the modified 3DOM carbon. However, the specific capacity decreases as cycling proceeds, apparently because lithium–tin alloy nanoparticles were detached from the carbon support by volume changes during charge–discharge processes. The rate performance of SnO₂‐coated 3DOM carbon is improved compared to 3DOM carbon.     

脉冲激光沉积β-FeSi2/Si(111)薄膜的工艺条件

用FeSi2合金靶作为靶材,采用准分子激光沉积法在Si(111)单晶基片上制备了单相的-βFeSi2薄膜,并将飞秒脉冲激光沉积法(PLD)引入到-βFeSi2薄膜的制备工艺中;用X射线衍射仪(XRD),场扫描电镜(FSEM),能谱仪(EDS),紫外可见光光谱仪研究了薄膜的结构、组分、表面形貌和光学性能。基片温度为500℃,采用KrF准分子脉冲激光沉积法可获得单相的-βFeSi2薄膜。衬底温度为550℃时,-βFeSi2出现迷津状薄层。采用飞秒脉冲激光法-βFeSi2薄膜的合成温度比准分子脉冲激光沉积法制备温度低50~100℃;薄膜的晶粒分布均匀连续,没有微米级的微滴;飞秒脉冲激光沉积效率比准分子激光的高1000倍以上,是一种快速高效的-βFeSi2薄膜沉积技术。     

Designing a New Generation of Proton‐Exchange Membranes Using Layer‐by‐Layer Deposition of Polyelectrolytes

All fuel cells utilizing the membrane‐electrode assembly have their ion‐conductive membrane sandwiched between bipolar plates. Unfortunately, applying conventional techniques to isolated polyelectrolyte membranes is challenging and difficult. A more practical alternative is to use the layer‐by‐layer assembly technique to fabricate a membrane‐electrode assembly that is technologically relatively simple, economic, and robust. The process presented here paves the way to fabricate ion‐conductive membranes tailored for optimum performance in terms of controlled thickness, structural morphology, and catalyst loading. Composite membranes are constructed through the layered assembly of ionically conductive multilayer thin films atop a porous polycarbonate membrane. Under ambient conditions, a fuel cell using a poly(ethylene oxide)/poly(acrylic acid) (PEO/PAA) composite membrane delivers a maximum power density of 16.5 mW cm^–2 at a relative humidity of 55 %, which is close to that of some commercial fuel cells operating under the same conditions. Further optimization of these systems may lead to new, ultrathin, flexible fuel cells for portable power and micropower applications.     

Facile Synthesis of Manganese‐Loaded Mesoporous Silica Materials by Direct Reaction Between KMnO4 and an In‐Situ Surfactant Template

A series of manganese oxide‐loaded SBA‐15 (MnSBA‐xh, x = 1, 2, 3, 4, 5, 6; h: hour(s)) mesoporous materials are synthesized via a facile, in‐situ reduction method with a surfactant template. The composite materials are characterized using Fourier‐transform infrared spectroscopy, X‐ray diffraction, N₂ sorption isotherms, X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy, energy‐dispersive spectroscopy, and CO oxidation catalysis. The results show that a high content of manganese (an atomic ratio of Mn/Si from 0.12 up to approximately 1) could be loaded into the channels of SBA‐15 when treated with an aqueous solution of potassium permanganate, while retaining the ordered mesostructure and large surface area of SBA‐15. Increasing the manganese oxide content results in a gradual decrease in the specific surface area, pore size, and pore volume. XPS spectra are employed to confirm the redox reaction between KMnO₄ and the surfactant. CO‐conversion tests on the calcined MnSBA‐2h sample (MnSBA‐2h‐cal) shows that it has a repeatable, and relatively high, catalytic activity.     

激光脉冲频率对纳米Si晶薄膜形貌的影响

在气压为10 Pa的惰性气体Ar环境下,采用XeCl准分子激光器(波长308 nm),调整激光单脉冲能量密度为4 J/cm2,激光烧蚀电阻率为3000Ω.cm的高纯单晶Si靶,在玻璃或Si衬底上沉积制备了纳米Si晶薄膜。实验中靶和衬底间距离保持为3 cm,对衬底既没有加温也没有冷却。拉曼(Raman)谱测量结果表明,所制备的薄膜中已有纳米Si晶粒形成。保持脉冲总数不变,分别取激光脉冲频率为1 Hz,3 Hz,10 Hz和20 Hz,相应沉积时间约为10 min,3.3 min,1 min和0.5 min,采用扫描电子显微镜(SEM)观察所得样品的表面形貌,不同脉冲频率下的结果比较显示,脉冲频率越大,制备的纳米Si晶薄膜的平均晶粒尺寸就越小,晶粒尺寸分布也越均匀。沉积动力学过程的非线性是导致实验出现该结果的原因。     

Templated Synthesis of Porous Capsules with a Controllable Surface Morphology and their Application as Gas Sensors

Porous capsules composed of hematite, silica, and hematite–silica composites are prepared by a templated synthesis method. Polyelectrolyte multilayer‐coated particles (PEMPs) are used to synthesize goethite nanocrystals and the resulting goethite‐nanocrystal‐embedded PEMPs (PEMP–goethite) are then used as templates to form porous capsules. The surface morphology and surface area of the porous capsules can be controlled by the size of the PEMP–goethite template, which is determined by the extent of growth of the goethite nanocrystals. By controlling the surface morphology and area, it is also possible to tune the sensitivity of the hematite capsules for use as gas‐sensing materials. This surfactant‐free approach is also used to synthesize silica and silica‐based composite capsules with a controllable porous shell thickness. This straightforward approach can also be extended to the synthesis of other porous capsules or particles with a controllable surface morphology.     

Hydrothermally Stable Thioether‐Bridged Mesoporous Materials with Void Defects in the Pore Walls

Hydrothermally stable thioether‐bridged mesoporous materials have been synthesized by one‐step co‐condensation of 1,4‐bis(triethoxysily)propane tetrasulfide (TESPTS) with tetramethoxysilane (TMOS) using cetyltrimethylammonimum bromide (CTAB) as the surfactant in basic conditions. The ordered mesoporous materials can be formed with a wide range of thioether concentrations in the mesoporous framework, as is seen by X‐ray diffraction (XRD) characterization. The results of N₂ sorption and transmission electron microscopy (TEM) reveal that the materials synthesized with TESPTS/TMOS molar ratios in the range 1:8–1:3 have extensive structural defect holes in the nanochannels. All materials exhibit enhanced hydrothermal stability, which is in proportion to the concentration of thioether bridging in the mesoporous framework. The thioether‐functionalized mesoporous materials are efficient adsorbents for removing Hg²⁺ and phenol from waste water. The Hg²⁺‐adsorption capacity of the material can be as high as 1500 mg g^–1.     

Combined Surface and Volume Templating of Highly Porous Nanocast Carbon Monoliths

Nanocast carbon monoliths exhibiting a three‐ or four‐modal porosity have been prepared by one‐step impregnation, using silica monoliths containing a bimodal porosity as the scaffold. Combined volume and surface templating, together with the controlled synthesis of the starting silica monoliths used as the scaffold, enables a flexible means of pore‐size control on several length scales simultaneously. The monoliths were characterized by nitrogen sorption, scanning electron microscopy, transmission electron microscopy, and mercury porosimetry. It is shown that the carbon monoliths represent a positive replica of the starting silica monoliths on the micrometer length scale, whereas the volume‐templated mesopores are a negative replica of the silica scaffold. In addition to the meso‐ and macropores, the carbon monoliths also exhibit microporosity. The different modes of porosity are arranged in a hierarchical structure‐within‐structure fashion, which is thought to be optimal for applications requiring a high surface area in combination with a low pressure drop over the material.