Generation of Large‐Area Highly‐Nonequlibrium Plasma in Pure Hydrogen at Atmospheric Pressure

Diffuse Coplanar Surface Barrier Discharge (DCSBD) is a novel type of atmospheric‐pressure plasma source developed for high‐speed large‐area surface plasma treatments. Basic characteristics of DCSBD operated in pure atmospheric‐pressure hydrogen were measured using optical and emission spectroscopy methods, and its potential for the surface treatment application was demonstrated by hydrogen plasma reduction of Cu₂O thin layers. The discharge generates a thin layer of diffuse non‐equilibrium plasma with a high power density of 70 Wcm^–3. The mean electron density and electron temperature derived from spectroscopic data were 1.3 x 10¹⁶cm^–3 and 19 x 10³K, and the surface Cu₂O layers forming a weak boundary were reduced to metallic copper within several seconds. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Scanning transmission X‐ray microscopy probe for in situ mechanism study of graphene‐oxide‐based resistive random access memory

Here, an in situ probe for scanning transmission X‐ray microscopy (STXM) has been developed and applied to the study of the bipolar resistive switching (BRS) mechanism in an Al/graphene oxide (GO)/Al resistive random access memory (RRAM) device. To perform in situ STXM studies at the C K‐ and O K‐edges, both the RRAM junctions and the I₀ junction were fabricated on a single Si₃N₄ membrane to obtain local XANES spectra at these absorption edges with more delicate I₀ normalization. Using this probe combined with the synchrotron‐based STXM technique, it was possible to observe unique chemical changes involved in the BRS process of the Al/GO/Al RRAM device. Reversible oxidation and reduction of GO induced by the externally applied bias voltages were observed at the O K‐edge XANES feature located at 538.2 eV, which strongly supported the oxygen ion drift model that was recently proposed from ex situ transmission electron microscope studies.     

Field emission scanning electron microscopy (FE-SEM) as an approach for nanoparticle detection inside cells

When developing new nanoparticles for bio-applications, it is important to fully characterize the nanoparticle's behavior in biological systems. The most common techniques employed for mapping nanoparticles inside cells include transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). These techniques entail passing an electron beam through a thin specimen. STEM or TEM imaging is often used for the detection of nanoparticles inside cellular organelles. However, lengthy sample preparation is required (i.e., fixation, dehydration, drying, resin embedding, and cutting). In the present work, a new matrix (FTO glass) for biological samples was used and characterized by field emission scanning electron microscopy (FE-SEM) to generate images comparable to those obtained by TEM. Using FE-SEM, nanoparticle images were acquired inside endo/lysosomes without disruption of the cellular shape. Furthermore, the initial steps of nanoparticle incorporation into the cells were captured. In addition, the conductive FTO glass endowed the sample with high stability under the required accelerating voltage. Owing to these features of the sample, further analyses could be performed (material contrast and energy-dispersive X-ray spectroscopy (EDS)), which confirmed the presence of nanoparticles inside the cells. The results showed that FE-SEM can enable detailed characterization of nanoparticles in endosomes without the need for contrast staining or metal coating of the sample. Images showing the intracellular distribution of nanoparticles together with cellular morphology can give important information on the biocompatibility and demonstrate the potential of nanoparticle utilization in medicine.     

微流控技术制备ZnO纳米线阵列及其气敏特性

利用微流控技术在微通道中制备了Zn O纳米线阵列,通过X射线衍射和扫描电子显微镜分别对纳米线的物相和表面形貌进行了表征.结果发现,合成的Zn O纳米线具有良好的c轴择优取向性和结晶度.同时,对Zn O纳米线阵列在丙酮、甲醇和乙醇气体中的气敏特性进行了研究,测试结果表明:在最佳工作温度(475?C)下,纳米线阵列对200 ppm(1 ppm=10-6)丙酮气体的最大灵敏度可达8.26,响应恢复时间分别为9和5 s;通过与传统水热法制备的Zn O纳米线的气敏性能相比较发现,基于微流控技术制备的纳米线阵列具有更高的灵敏度和更快的响应恢复速度.最后,从材料表面氧气分子得失电子的角度对Zn O纳米线气敏机理进行了讨论.     

ZnO@GQDs核壳结构量子点的制备及性能研究

采用原位聚合法制备了以ZnO量子点为核、石墨烯量子点（GQDs）为壳的ZnO@ GQDs核壳结构量子点。通过TEM和HR-TEM对量子点进行形貌和结构的分析表征。结果表明,合成的ZnO@ GQDs核壳结构量子点为球形,粒径为～7 nm,且尺寸均匀。PL光谱研究表明,新型量子点的发射峰位于369 nm,发光峰窄、强度高;相对于ZnO的本征发射峰,GQDs的引入使得ZnO@GQDs核壳量子点的荧光发射峰出现蓝移、强度变高,从而使复合量子点的荧光具有较纯的色度和较高的强度,说明GQDs的引入具有协同优化效应。该量子点有望应用于LED显示器件。     

溶剂热制备锂电池负极材料CNT-ZnFe2O4及其电化学性能

为了改善锂离子电池负极材料ZnFe₂O₄导电性差和循环寿命低的缺点,利用溶剂热反应方法制备了ZnFe₂O₄,并通过复合碳纳米管对ZnFe₂O₄进行改性。充放电测试结果表明：经过50次充放电后,碳纳米管复合改性后的ZnFe₂O₄容量保持在860 mA·h·g^-1,具有较好的循环稳定性。碳纳米管具有良好的导电性与导热性,改善了ZnFe₂O₄导电性差的缺点。     

非晶InGaZnO薄膜成分配比对透明性和迁移率的影响

利用固相反应法制备了富铟含量在不同成分配比下的高质量InGaZnO陶瓷靶材,采用脉冲激光沉积法,在基片温度为20℃、氧压为1Pa条件下,在石英玻璃衬底上生长了非晶InGaZnO薄膜,并对薄膜进行X射线衍射、透射吸收光谱、拉曼光谱与霍尔效应测试。通过对InGaZnO薄膜的测试表征,在较低温度条件下,铟含量较高的薄膜样品保持了非晶结构、可见光的高透明性和高电子迁移率,InGaZnO薄膜有望应用于电子器件。     

机械抛光铜金属表面对罗丹明的荧光增强效应

应用激光光谱学方法,研究了铜表面Rh6G分子的荧光增强效应对于金属衬底表面所形成的氧化层的依赖关系,探索了由于空气氧化而形成的氧化层在表面荧光增强效应中的重要意义和作用机理.实验采用罗丹明6G荧光探针分子,在532 nm连续光激发下,研究机械抛光铜金属衬底在经历不同氧化时间,对吸附其表面的Rh6G分子的荧光增强效果.研究结果表明,适当控制金属样品表面的氧化时间,金属铜表面对若丹明分子的荧光发射表现出猝灭和增强效应.金属氧化层起到了隔离荧光分子与金属表面的作用,减弱了由于激发态荧光分子向金属转移非辐射能量和在金属表面诱导反向偶极子而产生的荧光猝灭效应,从而提高了纯金属铜表面荧光增强辐射行为.因此在微纳金属衬底的荧光增强效应研究中,采用适当的实验手段,精确控制隔离层间距,是表面增强光谱获取的重要途径之一.     

Morphologically controlled preparation of CuO nanostructures under ultrasound irradiation and their evaluation as pseudocapacitor materials

Various morphologies of copper oxide (CuO) nanostructures have been synthesized by controlling the reaction parameters in a sonochemical assisted method without using any templates or surfactants. The effect of reaction parameters including molar ratio of the reactants, reaction temperature, ultrasound exposure time, and annealing temperature on the composition and morphology of the product(s) has been investigated. The prepared samples have been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDAX), and thermogravimetric analysis (TGA). It has been found that Cu₂(OH)₃NO₃ nanoplatelets are achieved in mild conditions which can be then converted to various morphologies of CuO nanostructures by either using high concentrations of OH⁻ (formation of nanorods), prolonging sonication irradiation (nanoparticles), or thermal treatment (nanospheres). Application of the prepared CuO nanostructures was evaluated as supercapacitive material in 1 M Na₂SO₄ solution using cyclic voltammetry (CV) in different potential scan rates ranging from 5 to 100 mV s⁻¹. The specific capacitance has been calculated using CV curves. It has been found that the pseudocapacitor performance of CuO can be tuned via employing morphologically controlled samples. Accordingly, the prolonged sonicated sample (nanoparticles) showed the high specific capacitance of 158 F.g⁻¹.