双金属/TiO2纳米管复合结构中增强的光电流

将传统半导体材料与金属微纳结构相结合,利用其表面等离激元共振效应,可有效地增强复合结构的光电转换效率,使其广泛地被用于光电化学和光电探测等领域.本文以氧化铝纳米管为模板,采用原子层沉积技术制备出高有序的TiO2纳米管,并通过电子束热蒸发技术在大孔径的纳米管薄膜中分别负载金、铝和双金属金/铝纳米颗粒,形成金属纳米颗粒/TiO2纳米管复合结构.研究结果表明,相对于纯TiO2纳米管,Au/TiO2复合纳米管在568 nm的可见光照射下,其光电流密度约有400%的提高;在365 nm紫外光照射下,Al/TiO2复合纳米管的光电流提高约50%;同时负载双金属Au和Al纳米颗粒的TiO2纳米管在整个紫外-可见光区域光电流均显著增强.     

原位聚合纳米Ni/聚苯乙烯复合材料及其热力学性能

 磁性聚苯乙烯(PS)材料有利于实现惯性约束聚变靶丸在辐射场中的无接触支撑。采用液相还原法制备了粒度为75~200 nm的Ni球形粒子,用原位聚合的方法制备了纳米Ni/PS复合材料。利用X射线衍射仪、傅氏转换红外线光谱分析仪、扫描电子显微镜及热重差示扫描量热仪分别研究了所得纳米Ni的特性、复合材料的结构及掺杂量对纳米Ni/PS复合材料的热力学行为的影响。研究结果表明：纳米Ni的掺杂能提高玻璃转变温度;纳米Ni的掺杂可以增大PS热分解焓变,在掺杂质量分数为1%~2%之间焓变达到最大;纳米Ni的掺杂降低了纳米Ni/PS复合材料热分解的比热容。     

Ag修饰TiO2纳米管紫外探测器的构筑及性能研究

以液相沉积法在FTO衬底上制备了TiO_2纳米管阵列,在室温下利用光沉积法在TiO_2纳米管表面修饰金属纳米Ag颗粒,并采用SEM、EDS、XRD对样品的形貌、成分、结构等进行表征.实验结果表明,制备的TiO_2纳米管分布均匀,由锐钛矿相组成,并在管壁有明显的纳米Ag颗粒附着.以Pt为对电极制备了Ag/TiO_2纳米管紫外探测器,光响应测试结果表明,Ag/TiO_2纳米管紫外探测器具有可见光盲特性,可以实现对紫外光的探测.与TiO_2纳米管紫外探测器相比,Ag修饰TiO_2纳米管紫外探测器光电流密度提高至91μA/cm2,开关比可达2 251,紫外探测性能显著提高.     

纳米结构ZnO薄膜的制备及其疏水特性

利用水热法制备出与透明导电衬底附着良好的多种纳米结构ZnO薄膜,包括纳米柱阵列、纳米管阵列、纳米片阵列等,方便集成在多种器件上。并且实现了阵列中纳米柱、纳米管外径的调节,柱外径在50~300 nm范围内可调,管外径在300~1 000 nm范围内可调。几种纳米薄膜均显示出较强的疏水性。在未经任何低表面能物质修饰的情况下,水在外径约300 nm的管状阵列表面的静态接触角已达138°。而在紫外光照射下,这些疏水的ZnO薄膜还可以变得亲水。这些研究结果为ZnO纳米阵列在相关方面的应用提供了重要依据。     

晶粒尺寸对1 MeV电子在金属Ni中能量沉积的影响

采用脉冲电沉积方法制备出高致密、高质量的纳米晶Ni, 并对其密度、组织成分和微观结构进行了表征. 利用高能粒子加速器产生的1 MeV高能电子为辐照源, 研究高能电子在纳米晶Ni和常规粗晶Ni中的能量损失. 通过辐照过程中放置的吸收剂量片来准确表征其电子的能量沉积. 结果表明, 晶粒尺寸对高能电子在材料中的能量沉积有明显的影响, 1 MeV电子在穿过一定厚度的金属Ni后, 在晶粒尺寸细小的纳米晶Ni中测得总的吸收剂量较大, 证明了高能电子在纳米材料中的总能量沉积较小, 从而表现出纳米材料抗辐照的优异性能. 关键词： 高能电子 纳米金属 辐射损伤     

金属铜纳米孔洞阵列膜制备方法研究

以多孔阳极氧化铝膜(anodic aluminum oxide，AAO)为模板，用真空蒸镀法复制了金属铜的纳米孔洞阵列膜，SEM结果表明，制备得到的金属铜纳米孔洞阵列膜形貌与AAO膜一致.此方法简单易行，能大规模生产，为纳米膜的工业化复制提供了一种新的工艺，为纳米线、纳米管等纳米阵列材料的合成与组装提供了有利的条件. 关键词： AAO模板 真空蒸镀 金属铜纳米孔洞阵列膜 纳米复制     

聚乙二醇-b-聚(4-乙烯基吡啶)/氢氧化钇杂化纳米管在金纳米粒子负载方面的应用

利用聚乙二醇-b-聚(4-乙烯基吡啶)(PEO-b-P4VP)胶束在氢氧化钇纳米管(YNTs)表面上的吸附,制备出被致密的P4VP内层和伸展的PEO外层包裹的杂化纳米管. 通过小分子交联剂1,4-二溴丁烷交联P4VP层可进一步稳定其结构. 然后将交联的杂化纳米管(CHNTs)作为金纳米粒子(GNPs)催化剂的新型纳米载体. 金纳米粒子被负载在交联杂化纳米管的P4VP层中(GNPs/CHNTs),并应用于催化对硝基苯酚的还原反应. 结果表明,这种新型的纳米载体在水溶液中具有良好的分散性, 对金纳米粒子有很高的负载效率(0.87 mmol/g),负载的金纳米粒子保持了很高的催化活性(12.9 μmol^-1min^-1),且GNPs/CHNTs有较好的可重复使用性.     

毛刺状竹节结构氮化硼纳米管的合成与生长机理

以非晶硼和氧化镍纳米颗粒为原料,在氨气中1100 oC下合成了毛刺状竹节结构的氮化硼纳米管. 利用X射线衍射和透射电镜研究了氮化硼纳米管的结构和形貌. 竹节结构纳米管表面的毛刺是六方氮化硼的纳米薄片. 提出了一种基于固态硼和气态二氧化硼扩散的毛刺形貌生长机理.     

主晶相为莫来石复合纳米晶的制备、结构表征及性能测试

以高岭土为原料,采用水热晶化法,制得了主晶相为莫来石的复合纳米晶。利用XRD、TEM、BET及TG－TDA以在不同条件下制得的纳米晶物相、粒度及热稳定性进行了表征。对复合纳米晶进行了CO、SO2程序升温脱附性能测试。对负载Ni、Mo、Co进行程序升温还原测试。结果表明：在脱附物中检测出CO2与固体硫,证明吸附质在纳米晶表面发生了反应。微米晶与纳米晶负载Ni、Co、Mn后,随着粒度的不同,负载上的氧化物与载体的相互作用力不同,而表现出不同的峰温与峰面积,表面负载上Ni、Co、Mn的氧化物与载体有结构效应,且随晶体表面结构的不同,而表现出不同的H2消耗量。     

热门的纳米管（Nanotubes are Hot）

纳米管现在非常热门 ,因为它有可能成为一种纤维状的微型新光源 .实际上 ,相当于纳米尺度的碳纤维光源早在 10 0年前就已有过 ,但近年来位于法国里昂的ＣｌａｕｄｅＢｅｒｎａｄｅ大学有一群科学家 ,他们以Ｓ .Ｐｕｒｃｅｌｌ教授为首一直在研究碳纳米管 .当电压较高时 ,管内的电子将快速地由阴极飞向阳极 ,形成场致发射 .这种效应的纳米管将来可以成为平板型展板的部件 .最近这个研究组在对纳米管的端点作温度调控时观测到了一系列有趣和很有用的特性 .首先他们改变纳米管一端的温度 ,这时纳米纤维管就能发射出电子、光或热 .与此同时 ,他…     

Bamboo-shaped carbon nanotubes generated by methane thermal decomposition using Ni nanoparticles synthesized in water-oil emulsions

Ni nanoparticles were synthesized using two water-in-oil emulsions formulated with different surfactants and using n-heptane as the organic phase and aqueous nickel acetate as the catalytic metallic precursor. Characterization by transmission electron microscopy showed that the Ni nanoparticles have diameters ranging from 3 to 12 nm, and that the surface is lightly oxidized. The decomposition of diluted methane catalyzed by the as-prepared Ni nanoparticles was studied in a thermogravimetric analyzer (TGA), operated in the 25–930 °C range. The weight gains measured during the analysis showed that the Ni nanoparticles decomposed methane above 480 °C, producing similar g.C/g.cat ratios (6–7) at the end of the tests. High resolution transmission electron microscopy (HRTEM) confirmed that the carbons collected at 930 °C were bamboo-shaped carbon nanotubes (BSCNTs) with well defined conical compartments. The average outside diameter of the tubes was between 30 and 60 nm.     

Tribological behaviors of dialkyldithiophosphate-encapsulated Ni nanoparticles prepared by microwave-assisted reaction

We applied the microwave-assisted heating method to prepare the pyridine dialkyldithiophosphate-encapsulated Ni (Ni-DDP) nanoparticles. The surface-encapsulated Ni particles were characterized by Fourier transform infrared spectrometer, thermogravimetric analysis, X-ray diffraction, and transmission electron microscopy. Their tribological behavior in lubricate base oil was investigated on four-ball machines. The results show that uniform Ni-DDP nanoparticles about 12 nm can be obtained using microwave heating device and also they exhibit good tribological behaviors dispersed in liquid paraffin.     

High-temperature pretreatment of Ni nanoparticles enhances the growth of high-density carbon fiber bundles during microwave plasma chemical vapor deposition

This paper presents an experimental study on the effect of the pretreatment procedure of Ni nanoparticles (NPs) on the growth of multiwalled carbon fiber (CNF) bundles by means of microwave plasma chemical vapor deposition (MPCVD). We used atomic force microscopy to investigate a series of pretreated Ni films. The structures and compositions of the CNFs on the via were investigated using scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy.The geometric shape of the Ni NPs was identified in terms of their roughness, which decreased upon increasing the pretreatment temperature, resulting subsequently in the synthesis of high-density CNFs. The diameter and shape of the Ni NPs were the dominant factors affecting the size and density of the CNFs bundles. We obtained CNFs that fully filled the via effectively; they might serve as potential interconnects in future nanodevices.     

Structure and photoluminescence of VAC-functionalized ZnO nanoparticles by plasma polymerization

A plasma polymerization method was used to modify the surfaces of ZnO nanoparticles, and the effects of plasma surface modification on photoluminescence (PL) property of ZnO nanoparticles were studied. High-resolution transmission electron microscopy images revealed that a thin film of vinyl acetate (VAC) polymer layer (∼4 nm) was uniformly deposited on the surfaces of the ZnO nanoparticles. The chemical structure of the polymer layer was identified by Fourier transform infrared (FTIR) experiments. The photoluminescence (PL) intensity of the ZnO nanoparticles was found to be significantly decreased by the deposited plasma films. For the particle of smaller size, the ultrathin film indicated better ultraviolet (UV) shielding ability.     

Direct production of carbon nanotubes decorated with Cu2O by thermal chemical vapor deposition on Ni catalyst electroplated on a copper substrate

Carbon nanotubes (CNTs) decorated with Cu₂O particles were grown on a Ni catalyst layer deposited on a Cu substrate by thermal chemical vapor deposition from liquid petroleum gas. Ni catalyst nanoparticles with different sizes were produced in an electroplating system at 45 °C using the corrosive effect of H₂SO₄ which was added to solution. These nanoparticles provide the nucleation sites for CNT growth avoiding the need for a buffer layer. The surface morphology of the Ni catalyst films and CNT growth over this catalyst was studied by scanning electron microscopy (SEM). High temperature surface segregation of the Cu substrate into the Ni catalyst layer and its exposition to O₂ at atmospheric environment, during the CNTs growth, lead to the production of CNTs decorated with about 6 nm Cu₂O nanoparticles. We used SEM to study the surface characteristics of Ni catalyst films and characteristic of grown CNTs. Raman spectroscopy, transmission electron microscopy (TEM), electron diffraction (EDX), X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) revealed the formation of CNTs. The selected area electron diffraction pattern, EDX, and XPS studies show that these CNTs were decorated with Cu₂O nanoparticles. This way of fabrication is the easiest and lowest cost method.     

Carbon nanotubes as nanoparticles collector

This communication reports on a new method for the collection of nanoparticles using carbon nanotubes (CNT) as collecting surfaces, by which the problem of agglomeration of nanoparticles can be circumvented. CNT (10–50 nm in diameter, 1–10 μm in length) were grown by thermal CVD at 923 K in a 7 v/v% C₂H₂ in N₂ mixture on electroless nickel-plated copper transmission electron microscopy (TEM) grids and Monel coupons. These samples were then placed downstream of an arc plasma reactor to collect individual copper nanoparticles (5–30 nm in diameter). It was observed that the Cu nanoparticles preferentially adhere onto CNT and that the macro-particles (diameter >1 μm), a usual co-product obtained with metal nanoparticles in the arc plasma synthesis, are not collected. Cu–Ni nanoparticles, a catalyst for CNT growth, were deposited on CNT to grow multibranched CNT. CNT-embedded thin films were produced by re-melting the deposited nanoparticles.     

Preparation of Halloysite Nanotubes/Polystyrene (HNTs/PS) Core‐shell Particles via Soap‐less Microemulsion Polymerization

Halloysite nanotubes/polystyrene (HNTs/PS) inorganic/organic core‐shell particles were prepared via a convenient soap‐less microemulsion polymerization. The inorganic cores were pre‐treated with allyl alcohol (AA) and the polymer shells were prepared successfully by the facile soap‐less microemulsion polymerization of styrene (St) with the allyl alcohol‐modified halloysite nanotube (AA‐HNT) nanoparticles as seeds, and potassium persulfate (KPS) as initiator in water. The products were characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The morphologies of the HNTs/PS core‐shell particles were characterized by transmission electron microscopy (TEM). The mechanism of the nucleation is also mentioned.     

Mechanical and Thermal Properties Enhancement of Poly(Lactic Acid)/Halloysite Nanocomposites by Maleic-Anhydride Functionalized Rubber

Poly(lactic acid) (PLA)/halloysite composites were prepared using melt compounding followed by compression molding. Maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) was used to toughen the PLA composites. The mechanical properties of the PLA composites were studied through tensile, flexural, and impact tests. The thermal properties were characterized by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The fracture surfaces of the composites were assessed by using field emission scanning electron microscopy (FESEM). The impact strength and thermal properties of the PLA/halloysite composites were increased by addition of SEBS-g-MAH.     

Inter- and intra-agglomerate fracture in nanocrystalline nickel

In situ tensile straining transmission electron microscopy tests have been carried out on nanocrystalline Ni. Grain agglomerates (GAs) were found to form very frequently and rapidly ahead of an advancing crack with sizes much larger than the initial average grain size. High-resolution electron microscopy indicated that the GAs most probably consist of nanograins separated by low-angle grain boundaries. Furthermore, both inter- and intra-GA fractures were observed. The observations suggest that these newly formed GAs may play an important role in the formation of the dimpled fracture surfaces of nanocrystalline materials.     

Carbon nanotubes decorated by graphitic shells encapsulated Cu nanoparticles

Carbon nanotubes (CNTs) decorated by graphitic shells encapsulated Cu nanoparticles were fabricated by low-energy hydrocarbon ion deposition with using Cu as hold substrate at 900°C. Scanning electron microscopy shows that the surface of CNTs becomes very coarse by hydrocarbon ion treatment. The investigation of transmission electron microscope shows that the full surfaces of CNTs are coated by dense graphitic shells encapsulated Cu nanoparticles. The graphitic shells consist of 7–10 layers and the size of Cu core is 1–2 nm.