x光纳米光刻掩模的离子束制备法

重离子束轰击聚碳酸酯后,对样品进行陈化和紫外线照射敏化,在优化条件下蚀刻后得到纳米孔径核孔膜。利用电化学沉积技术在核孔膜中制备了最小孔径为30纳米的铜纳米线。获得的铜纳米线/聚碳酸酯可以作为x光纳米光刻的掩模。     

模板合成法制备ZnO纳米线的研究

在草酸和硫酸电解液中分别制备了孔径为40 nm和20 nm左右的多孔氧化铝模板,用直流电化学沉积的方法,在模板孔洞内电解沉积Zn,对其进行高温下的氧化,可得到高度有序的ZnO纳米线.扫描电子显微镜观察显示,多晶的Zn纳米线均匀地填充到多孔氧化铝六角排布的孔洞里,直径与模板孔径相当.X射线衍射谱测量证实,制备的Zn纳米线和ZnO纳米线均为多晶结构,并且对比了模板孔径对纳米线结构的影响.测量了多孔氧化铝厚膜和Zn/Al2O3组装体的吸收光谱,发现其在红外波段的吸收系数有逐渐降低的趋势.     

阳极氧化法制备氧化铝纳米线

将Al片在较高的电压下进行阳极氧化,制备了氧化铝纳米线。其形成机制主要是多孔氧化铝膜生长的同时,其微结构单元阵列在薄膜应力作用下沿薄壁处破裂,从而生成了氧化铝纳米线。扫描电镜和透射电镜观测表明,所得产物结构外形基本一致,呈凹柱面正三棱柱形,表观直径约30～300nm,长度为几微米至数十微米。采用BET法对产物的比表面积进行测量,实验值为5.8×104m2/kg,接近于理论计算值6.2×104m2/kg。实验表明,这种氧化铝一维纳米结构材料对超小Ag和CdS纳米颗粒具有较强的吸附能力,对很难用传统的过滤和离心沉淀法去除的超小纳米颗粒(直径小于10nm)也能做到有效吸附,有望成为超级吸附与过滤材料。     

Selective Atmospheric Pressure Chemical Vapor Deposition Route to CdS Arrays,Nanowires, and Nanocombs

CdS arrays, nanowires, and nanocombs were selectively prepared through an atmospheric pressure chemical vapor deposition (APCVD) process with CdCl₂ and S as sources. The morphologies could be controlled by adjusting the deposition position, the temperature, and the flux of the carrier gas. The phase structure, morphologies, and photoluminescence properties of the CdS products were investigated by X‐ray diffraction (XRD), scanning electron microscopy (SEM), high‐resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra. The formation mechanism of the nanowires is discussed on the basis of the experimental results. The adopted synthetic route is expected to be applied in the synthesis of other metal sulfide one‐dimensional (1D) nanostructures.     

PZT纳米铁电薄膜的生长行为和介电性能及微结构

采用溶胶-凝胶(sol-gel)自旋涂敷法在Si(100)基多孔氧化铝模版介质上制备了Pb(Zr0.53Ti0.47)O3(PZT)纳米铁电薄膜(厚度25nm).利用电化学方法在多孔氧化铝模版孔道内(孔径25nm)生长Au纳米线,作为底电板一部分.利用x射线衍射(XRD)、扫描电镜(SEM)及场发射透射电镜(FE-TEM)对PZT纳米铁电薄膜的生长行为、表面形貌和微结构进行了研究.XRD谱图表明PZT纳米铁电薄膜具有(111)择优取向;SEM像显示PZT纳米铁电薄膜结构致密,晶粒呈椭球状,平均尺寸为22nm.剖面TEM像证实PZT纳米铁电薄膜与Au纳米线直接接触,它们之间的界面呈现一定程度的弯曲;部分Au纳米线顶端出现分枝展宽现象.介电谱表明PZT纳米铁电薄膜的介电常数在低频区域(频率小于104 Hz)从760迅速下降到100,然后基本保持在100,直至测量频率升高到106 Hz.低频区域内介电常数的迅速下降是由于空间电荷极化机制所致;介电损耗在4 000 Hz附近出现峰值(来源于空间电荷的共振吸收)也证实了空间电荷极化机制的存在.     

Electrodeposition and Characterization of Bismuth Telluride Nanowires

In this work, we report thermoelectric measurements on electroplated bismuth telluride nanowires. Porous polycarbonate membranes, obtained by ion-track irradiation lithography, were chosen as electroplating templates. Bismuth telluride nanowires were achieved in acidic media under potentiostatic conditions at −100 mV versus saturated silver chloride electrode. The filling ratio of the pores was increased to 80% by adding dimethyl sulfoxide to the electrolyte. Whatever the experimental conditions, the nanowires were polycrystalline in the rhombohedral phase of Bi₂Te₃. Finally, the power output of arrays of bismuth telluride nanowires was analyzed as a function of load resistance. The results were strongly dependent on the internal resistance, which can be significantly reduced by the presence of dimethyl sulfoxide during electroplating.     

Effect of postgrowth heat treatment on the structural and optical properties of InP/InAsP/InP nanowires

The effect of the postgrowth annealing of InP/InAsP/InP heterostructural nanowires produced by molecular-beam epitaxy on their structural and optical properties is studied. It is shown that the procedure of short-term (1 min) annealing in an argon atmosphere provides a means for increasing the emission intensity of InAsP quantum dots, suppressing the emission from InAsP quantum wells formed as a result of lateral growth, and substantially reducing the density of structural defects in the nanowires.     

BaTiO3铁电纳米膜制备及物性和微结构表征

采用脉冲激光淀积法在硅基氧化铝纳米有序孔膜版介质上（膜版孔径平均尺寸20nm,内生长Pt纳米线作为底电极一部分）制备了BaTiO3铁电纳米膜,并对其物性（铁电和介电性能）和微结构进行了表征。结果表明厚度170nm BaTiO3铁电膜的介电常数,随着测量频率的增加（103Hz至106Hz）,从400缓慢下降到350;介电损耗在低频区域（103～105Hz）从0.029缓慢增加到0.036,而在高频率区域（〉105Hz）后,则迅速增加到0.07。这是由于BaTiO3铁电薄膜的介电驰豫极化引起的。电滞回线测量结果表明,该薄膜的剩余极化强度为17μC/cm2,矫顽场强为175kV/cm。剖面扫描透射电子显微镜（STEM）图像表明,BaTiO3纳米铁电薄膜与底电极Pt纳米线直接相连接,它们之间的界面呈现一定程度的弯曲。选区电子衍射图和高分辨电子显微像均表明BaTiO3铁电薄膜具有钙钛矿型结构。在BaTiO3纳米铁电薄膜退火晶化处理后,部分Pt纳米线的再生长导致顶端出现分枝展宽现象。为了兼顾氧化铝纳米有序孔膜版内的金属纳米线有序分布和BaTiO3纳米薄膜结晶度,合适的退火温度是制备工艺过程的关键因素。     

Elaborately Aligning Bead‐Shaped Nanowire Arrays Generated by a Superhydrophobic Micropillar Guiding Strategy

Bead‐shaped 1D structures are of great interest due to their unique applications in mesoscopic optics/electronics and their specific ability to collect tiny droplets. Here, a novel method to fabricate aligning bead‐shaped nanowire arrays assisted by highly adhesive superhydrophobic surfaces based on a micropillar guiding strategy is presented. Different from previous fabrication techniques, bead‐shaped nanowires generated in this method are strictly oriented in a large scale. Rayleigh instability, which occurs at ultralow polymer concentration, can introduce bead‐shaped nanowires at the cost of structural strength. Thus, PS spheres are more suitable to serve as bead building blocks to generate firm bead‐shaped nanowire arrays. The bead number is tunable by tailoring the polystyrene‐sphere/polyvinyl‐formal ratio. Furthermore, as‐prepared bead‐shaped nanowires have the unique ability to directionally drive tiny drops and collect coalesced microdroplets when placed in mist. With an increase in humidity, the nanowires show a segmented swelling behavior in the “bead” parts whereas the “joint nanowire” parts remain the same. Because such bead‐shaped nanowires are formed regularly, collected microdroplets upon the beads would not interact with each other. The findings offer new insight into the alignment of bead‐shaped nanostructures and might provide promising opportunities in fundamental research and for industrial applications.     

纳米结构材料在太阳电池中的应用

各种纳米结构材料具有许多优异的光伏性质。例如量子阱具有良好的带隙可调谐能力,纳米薄膜具有较好的光吸收特性,量子点具有多激子产生能力,纳米线具有低反射特性等。重点评述了采用量子阱、纳米薄膜、各种一维纳米结构、纳米晶粒或量子点等不同纳米结构材料,制作的太阳电池的光伏性能及其近年研究进展。指出了各自的潜在优势与存在问题,并提出了设计与制作新型纳米结构太阳电池的若干技术对策,如选择合适的纳米结构材料、制备有序的量子点结构、设计叠层结构等一系列技术手段,借以提高太阳电池的光电转换效率。可以预期,高效率、低成本和长寿命的纳米结构太阳电池将会对未来光伏产业的发展产生重要影响。     

Studies of Surface‐Modified Gold Nanowires Inside Living Cells

The cytotoxicity of various surface‐functionalized gold nanowires with different aspect ratios is investigated by (3‐(4,5‐dimethylthiazol‐2‐yl)2,5‐diphenyltetrazolium bromide) (MTT) assays for two cell lines, fibroblast and HeLa. It is found that functionalized gold nanowires with a diameter of 200 nm and lengths up to a few micrometers can be readily internalized by both types of cells regardless of the type of surface functionalization. However, the cytotoxicity of the gold nanowires is observed to depend on their surface modification. Serum‐coated gold nanowires are the least toxic, whereas more than 50 % of the cells are damaged in the presence of mercapto‐acid‐modified gold nanowires even at very low concentrations (10³ nanowires mL^–1). Nanowires with different aspect ratios exhibit the same cytotoxicity within limits of experimental error. However, the uptake efficiency is found to be higher for shorter nanowires as compared to their longer counterparts. Therefore, we conclude that internalized nanowires with high aspect ratios are more toxic to cells than nanowires with low aspect ratios. Positively charged aminothiol‐modified gold nanowires are employed to deliver both plasmid DNA and probe molecules into cells without compromising the viability of the cells. The local environment of individual nanowires within the cells is studied by monitoring the fluorescence signal from probe molecules attached to the nanowires.     

Growth methods,enhanced photoluminescence,high hydrophobicity and light scattering of 4,4′-bis(1,2,2-triphenylvinyl)biphenyl nanowires

4,4′-bis(1,2,2-triphenylvinyl)biphenyl (BTPE) nanowires have been facilely grown by either post-annealing its vacuum-sublimed amorphous film or slowly evaporating its chloroform solution. The morphology and density of the nanowires can be easily tuned by changing the growth conditions. For example, isolated single nanowires were readily obtained by thermally depositing the BTPE on a heated substrate, while bundles of nanotubes can be achieved by slowly evaporating a droplet of the BTPE solution. The self-assembled BTPE nanowires show enhanced and blue-shifted photoluminescence compared with that of its amorphous film. The nanowires exhibit a highly hydrophobic surface with a water contact angle of 126°. Also, the BTPE nanowires scatter the light effectively due to the random orientation of the wires. By depositing the BTPE nanowires on the backside of the glass substrate as a scattering media for organic light-emitting diodes, a 31.5% efficiency improvement has been achieved.     

Hydroxide‐Membrane‐Coated Pt3Ni Nanowires as Highly Efficient Catalysts for Selective Hydrogenation Reaction

Rational design of effective catalysts with both high activity and selectivity is highly significant and desirable for hydrogenation reaction. In this paper, for the first time an efficient approach to controllably construct 1D metal nanowires (NWs) coated with hydroxide (Ni_xM(OH)₂ (M = Mn, Fe, Co, Cu, and Al)) membranes as highly active and selective hydrogenation catalysts is reported. The optimized Ni₃₂Cu(OH)₂ membrane coated Pt₃Ni nanowires show much enhanced selectivity of 87.9% for the hydrogenation of cinnamaldehyde to hydrocinnamaldehyde instead of hydrocinnamyl alcohol, in contrast with the pristine Pt₃Ni nanowires and Pt₃Ni nanowires on Ni(OH)₂ membranes. The enhanced selectivity of Pt₃Ni@Ni₃₂Cu(OH)₂‐2 NWs is ascribed to confinement/poisoning effects of the coated Ni₃₂Cu(OH)₂ membranes as well as the intimate interaction between the Pt₃Ni NWs and Ni₃₂Cu(OH)₂ membranes, as confirmed by X‐ray photoelectron spectroscopy. The coated structures also show good stability after five recycle runs. The present work highlights the importance of surface engineering for the design of multicomponent composites with desirable activity and selectivity toward hydrogenation reaction and beyond.     

Endocytosis‐Enabled Construction of Silica Nanochannels Crossing Living Cell Membrane for Transmembrane Drug Transport

Artificial transmembrane channel (ATC) analogs are developed for overcoming biological membrane barriers and realizing transmembrane drug delivery, which are mostly studied within artificial lipid bilayers and thus lacked enough stability in practical applications on living cells. Here, natural endocytosis of silica‐based 1D nanomaterials (nanowires) with an ultrahigh aspect ratio is investigated. Enlightened by partially endocytosed ultralong silica nanowires, ATC that can penetrate living cell membranes for transmembrane transportation of small drug molecules is creatively constructed, resulting in enhanced drug delivery efficacy and decreased the half maximal inhibitory concentration. For the first time, an in‐depth study of the cellular uptake of 1D nanomaterials with ultrahigh aspect ratios (from 10 to 120) into living cells is carried out. Through confocal laser scanning microscopy observation, the endocytosis process of ultralong nanowires, including full uptake of short nanowires and partial uptake of longer nanowires, is clarified. Theoretical simulation is performed to give a fundamental understanding on the endocytosis mechanism of ultralong 1D silica nanowires. The simulation results demonstrate the time‐dependent internalization dynamics of the nanowires, which agrees well with our experimental results. This work not only clarifies the cellular interaction between 1D nanomaterials and living cells, but also pioneers the use of natural endocytosis of 1D nanomaterials for constructing ATC.     

General Synthesis of Single‐Crystal Tungstate Nanorods/Nanowires: A Facile,Low‐Temperature Solution Approach

The general large‐scale synthesis of a family of single‐crystalline transition metal tungstate nanorods/nanowires is easily realized by a hydrothermal crystallization technique under mild conditions using cheap and simple inorganic salts as precursors. Uniform tungstate nanorods/nanowires such as MWO₄ (M = Zn, Mn, Fe), Bi₂WO₆, Ag₂WO₄, and Ag₂W₂O₇ with diameters of 20–40 nm, lengths of up to micrometers, and controlled aspect ratios can be readily obtained by hydrothermal transformation and recrystallization of amorphous particulates. This novel and efficient pathway toward various kinds of related low‐dimensional tungstate nanocrystals under mild conditions could open new opportunities for further investigating the novel properties of tungstate materials.     

SnO2掺Ag纳米线的制备、结构表征及光学性质研究

用化学气相沉积法在管式炉中制备了SnO2掺Ag纳米线.纳米线直径约50 nm,长几十微米.通过XRD、TEM和Raman谱仪等测量确定SnO2掺Ag纳米线为金红石型结构,XPS谱表明样品中含有Sn、O和Ag元素,Ag的浓度约为1.8 at.%,室温PL谱显示样品在626nm处有很强的红光发射峰.     

Temperature‐Controlled Catalytic Growth of ZnS Nanostructures by the Evaporation of ZnS Nanopowders

ZnS nanostructures with different morphologies, sizes, and microstructures were synthesized by the evaporation of ZnS nanopowders. Based on the appearance of the as‐synthesized products, we show that substrate temperature and catalyst are the critical factors for controlling the size and the structure of various kinds of ZnS nanostructures, such as nanorods, nanowires, nanobelts, and nanosheets. Within a certain temperature range, products with a specific morphology can be obtained. Therefore, it may be possible to obtain ZnS nanostructures with a specific morphology by controlling the reaction temperature and catalyst. This represents an important step toward the design and control of nanostructures. High‐resolution electron microscopy revealed that most of the nanorods and nanowires grew along the [100] direction, whereas most of the nanobelts and nanosheets grew along [001]. Photoluminescence properties and growth mechanisms of these as‐synthesized ZnS nanostructures are discussed.     

Low Electrical Percolation Threshold of Silver and Copper Nanowires in Polystyrene Composites

Silver and copper nanowires have been synthesized using a scalable method of AC electrodeposition into porous aluminum oxide templates, which produces gram quantities of metal nanowires ca. 25 nm in diameter and up to 5 and 10 μm in length for Ag and Cu, respectively. The nanowires have been used to prepare polystyrene nanocomposites by solution processing. Electrical resistivity measurements performed on polymer nanocomposites containing different volume fractions of metal indicate that low percolation thresholds of nanowires are attained between compositions of 0.25 and 0.75 vol %.     

Optical properties of photodetectors based on single GaN nanowires with a transparent graphene contact

We report the fabrication and optical and electrical characterization of photodetectors for the UV spectral range based on single p–n junction nanowires with a transparent contact of a new type. The contact is based on CVD-grown (chemical-vapor deposition) graphene. The active region of the nitride nanowires contains a set of 30 radial In_0.18Ga_0.82N/GaN quantum wells. The structure is grown by metal-organic vaporphase epitaxy. The photodetectors are fabricated using electron-beam lithography. The current–voltage characteristics exhibit a rectifying behavior. The spectral sensitivity of the photodetector is recorded starting from 3 eV and extending far in the UV range. The maximal photoresponse is observed at a wavelength of 367 nm (sensitivity 1.9 mA/W). The response switching time of the photodetector is less than 0.1 s.     

Crystallization of Amorphous Tris(8‐hydroxyquinoline)aluminum Nanoparticles and Transformation to Nanowires

Amorphous tris(8‐hydroxyquinoline)aluminum (AlQ₃) nanoparticles can be grown directly into α‐phase crystalline nanowires in a one‐step heat treatment. At the most appropriate Ar pressure, heating time, and heating temperatures (between 150 and 190 °C), fine and long nanowires are obtained. The growth of the nanowires is dictated by the anisotropic bonding in α‐AlQ₃ crystals. The growth mechanism is illustrated by the concept of nucleation and molecular migration. Two exotherms are revealed, from differential scanning calorimetry analyses, in the transformation process of AlQ₃ amorphous nanoparticles to crystalline nanowires. The first exotherm is the transition from amorphous nanoparticles to the γ‐phase, and the second exotherm is the transition from the γ‐ to the α‐phase. By means of Kissinger plots, the activation energies for the crystallization of the γ‐phase and the transition from the γ‐ to the α‐phase are calculated, for the first time, to be 9.7 and 12.1 kJ mol^–1, respectively. A blue‐shift and higher intensity of photoluminescence after heat treatment are also demonstrated.