Single-crystalline zinc oxide nanowires as photoanode material for dye-sensitized solar cells

This study reports the use of single-crystalline and well-aligned ZnO nanowires as photoanode material for dye-sensitized solar cells. The ZnO nanowires are grown on fluorine-doped tin oxide coated glass substrates without catalysts by thermal evaporation. In spite of low roughness factors of around 25 for the nanowire photoanodes, the fabricated solar cells yield power conversion efficiencies of around 1.3% under AM 1.5G (100 mW cm-2) illumination. Moreover, fill factors of around 0.5 have been achieved and are relatively high when compared with reported values from ZnO nanowire photoanodes. The results reveal the advantage of using single-crystalline nanowires as photoanode material and provide clues for the advancement of nanowire based dye-sensitized solar cells.     

Facile one-pot preparation of silver nanowires using an alcohol ionic liquid

Silver nanowires have attracted considerable attention in the past decade, due to their unique physical and chemical properties, which can lead to a wide variety of potential applications. In this work, silver nanowires have been fabricated using an alcohol ionic liquid by a one-step method in the absence of any extra capping agents. The method is based on the reduction of AgNO₃ by 1-(3-hydroxylpropyl)-3-methylimidazolium tetrafluoroborate (C₃OHmimBF₄) in an aqueous solution at 180°C for 18 h. The products were characterized by a scanning electron microscope (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectrograph (EDS), and powder X-ray diffractometry (XRD). The experimental results indicate that both reaction temperature and special properties of C₃OHmimBF₄ play important roles in the formation of silver nanowires.     

Fishbone-like platinum-nickel nanowires as an efficient electrocatalyst for methanol oxidation

Platinum (Pt)-based electrocatalyst with low Pt content and high electrocatalytic performance is highly desired in fuel cell applications. Herein, we demonstrated that platinum-nickel (Pt-Ni) nanowires with an average composition of PtNi₃ and a fishbone structure can be readily synthesized and used as an efficient electrocatalyst toward methanol oxidation reaction (MOR). The PtNi₃ fishbone-like nanowires (PtNi₃-FBNWs) present features such as richer Pt on the surface than in the bulk, high-index facets on the rough surface, and polyhedral facets at the ends of side chains. Such compositional and structural features could be determinative to the enhanced performance in the electrocatalysis of MOR. Compared with commercial 20% Pt/carbon black (Pt/C), the specific activity and mass activity of the PtNi₃-FBNWs are enhanced by approximately 4.76 and 3.02 times, respectively. The stability of electrocatalysis is significantly improved as well. Such comprehensive enhancement indicates that the PtNi₃-FBNWs would be a promising candidate toward MOR in fuel cells.

     

模板法制备CuO分叉纳米线

通过3次阳极氧化制备具有分叉结构的氧化铝模板,在氧化铝模板的纳米孔洞中,用电化学方法沉积铜纳米线,经过500℃、30h氧化处理,成功制备出具有分叉结构的CuO纳米线.分别用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射仪(XRD)对样品的形貌和晶体结构进行了表征测试.SEM观察结果氧化铝模板的纳米孔洞相互平行、分布均匀,枝干的孔心距约为120nm,枝叉的孔心距约为70nm.TEM观察显示纳米线各部分粗细均匀.样品的XRD分析表明分叉纳米线阵列的晶体结构为CuO.     

Microwave-assisted preparation of calcium sulfate nanowires

We have successfully developed a new synthetic route for the rapid preparation of calcium sulfate nanowires by thermal transformation of calcium dodecyl sulfate (CDS) in organic solvents of ethylene glycol (EG) and N,N-dimethylformamide (DMF). The products are characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM), and determined to be single-phase CaSO₄·0.5H₂O consisting of single-crystalline nanowires with aspect ratio up to about 62. In this method, the different types of organic solvents used have no obvious influences on the morphology, phase, and formation time of the product. The microwave heating can remarkably shorten the reaction time compared with conventional heating methods.     

无机粉体抗菌材料的研究进展

无机抗菌剂由于其独特的性能而成为当前抗菌材料领域的研究开发热点.本文对无机抗菌剂的分类、制备方法、抗菌机理及应用进行了综述,并结合应用现状讨论了无机粉体抗菌材料的发展前景及存在的问题.     

Rheology of cellulose nanofibrils and silver nanowires for the development of screen-printed antibacterial surfaces

Journal of Materials Science - TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl)-oxidized cellulose nanofibrils (T-CNF) and silver nanowires (Ag NWs) were formulated as active inks. Their rheological...     

Tinplate as an engineering material

Tinplate can be made in a variety of grades, each of which exhibits slightly different properties, so that the grade can be tailored to a particular end-use. This review describes the characteristics and properties of modern tinplate and shows how these can be exploited in particular end-uses.     

Carbon as an electronics material

Carbon is as natural an electronic material as silicon, and it has also the advantages that come from the multiplicity of forms available. We concentrate on the properties and potential uses of carbon in nanotubes, polymers and composites of the two. Unlike silicon, organic molecules can produce light of almost any wavelength and also multiple wavelengths including white. It is likely to be used initially for LCD backplanes. Nanotubes have shown potential for use in cold cathodes. Progress towards using them in displays is slow. However, commercial use in microwave resonators seems to be imminent. There has been substantial progress in understanding the use of conjugated polymers in photovoltaics, where polymer composites with nanotubes or blends of organic semiconductors promise to continue progress to greater efficiency and cost effectiveness. The understanding of fundamental processes has yet to develop to a point where it is of direct value to electronics. Simplifications based on semi-classical device physics appear to be able to short circuit these difficulties.     

锆、钛复合掺杂锂钴氧化物正极材料制备及电化学性能研究

以碳酸锂、氧化钴为主要原料,掺入化学计量的超细二氧化锆、超细二氧化钛,按球料比3:1,在转速500r/min经1h行星式球磨后,经900℃固相烧结制备了锂离子电池正极材料LiCo0.9Zr0.03Ti0.07O2,用X射线衍射(XRD)、扫描电镜(SEM)对材料的结构与形貌进行了研究,结果表明Li0.9Zr0.03Ti0.07O2与LiCoO2一样具有六方层状结构.在0.2C倍率下材料的初始放电容量达147mAh/g,2C倍率下初始放电容量达140.5mAh/g,3.6V放电平台比例达89.6%,500次循环后容量衰减7.5%,材料大电流放电性能好、循环寿命长.     

Optimisation of the epi-ready semi-insulating GaAs wafer preparation procedure

The surface quality is crucial for growth of epitaxial layers on III-V semiconductor substrates. In this work the procedures of epi-ready semi-insulating (SI) GaAs wafer preparation were developed. The atomic force microscopy (AFM), triple crystal X-ray diffraction (TCD) and X-ray photoelectron spectroscopy (XPS) were used to monitor morphology and composition of substrates with different chemical treatment history. We propose an optimised epi-ready SI GaAs wafer preparation procedure involving NH₄OH:H₂O₂:H₂O/NaOCl:H₂O₂:H₂O etching/polishing.     

Optimal design of material properties and material distribution for multiple loading conditions

An extension of recent work¹ on the simultaneous optimization of material and structure to address the design of structures under multiple loading conditions is presented. Material properties are represented in the most general form possible, namely, as elements of the unrestricted set of positive-semi-definite constitutive tensors of a linearly elastic continuum. Existence of solutions can be shown when the objective is a weighted average of compliances and a resource constraint measured as the 2-norm or the trace of the constitutive tensors is included. The optimized material properties can be derived analytically. The optimization of the layout of the material leads to a sizing problem of structural optimization involving a non-linear, non-smooth elasticity analysis. The computational solution of this problem is discussed and illustrated with examples.     

铜型无机抗菌材料的改性研究

研究了添加电解质、表面活性剂和有机溶剂对铜型抗菌白炭黑性能的影响.采用溶胶-凝胶法制备出白炭黑载体,选用Cu2+作为抗菌离子,亚硝酸钠(电解质)、十二烷基苯磺酸钠(表面活性剂)和乙醇(有机溶剂)作为添加剂.运用ICP、粒度分布仪等对改性后的抗菌白炭黑进行表征,采用菌落计数法(菌种选用大肠杆菌)对改性后样品的抗菌性能进行研究.结果表明:通过改性,铜型抗菌白炭黑的抗菌离子含量和杀菌率均有所提高;粒径均一,粒度分布窄;热稳定性较好.     

Use of phosphine as an n-type dopant source for vapor-liquid-solid growth of silicon nanowires

Phosphine (PH3) was investigated as an n-type dopant source for Au-catalyzed vapor-liquid-solid (VLS) growth of phosphorus-doped silicon nanowires (SiNWs). Transmission electron microscopy characterization revealed that the as-grown SiNWs were predominately single crystal even at high phosphorus concentrations. Four-point resistance and gate-dependent conductance measurements confirmed that electrically active phosphorus was incorporated into the SiNWs during VLS growth. A transition was observed from p-type conduction for nominally undoped SiNWs to n-type conduction upon the introduction of PH3 to the inlet gas. The resistivity of the n-type SiNWs decreased by approximately 3 orders of magnitude as the inlet PH3 to silane (SiH4) gas ratio was increased from 2 x 10(-5) to 2 x 10(-3). These results demonstrate that PH3 can be used to produce n-type SiNWs with properties that are suitable for electronic and optoelectronic device applications.     

铜纳米粒子的可控制备及其抗菌性能研究

以氯化铜为铜源,水合肼为还原剂,十六烷基三甲基溴化铵(CTAB)为稳定剂,氨水为络合剂,通过液相还原法合成了纳米铜粉。通过改变还原剂浓度制备了4组不同粒径纳米铜粉末,FESEM等表征发现,随着水合肼浓度的降低,纳米铜粉粒径增加。通过肉汤稀释振荡培养法测试纳米铜的最小抑菌浓度,结果表明,随着纳米铜粒径的增加,抗菌性能降低,所合成纳米铜的最小抑菌浓度在750～3000mg/L;初步分析认为铜纳米粒子主要是通过水解或电离出铜离子而发挥抗菌作用。     

Solid-state diffusion as an efficient doping method for silicon nanowires and nanowire field effect transistors

In this work we investigate doping by solid-state diffusion from a doped oxide layer, obtained by plasma-enhanced chemical vapor deposition (PECVD), as a means for selectively doping silicon nanowires (NWs). We demonstrate both n-type (phosphorous) and p-type (boron) doping up to concentrations of 10(20) cm(-3), and find that this doping mechanism is more efficient for NWs as opposed to planar substrates. We observe no diameter dependence in the range of 25 to 80 nm, which signifies that the NWs are uniformly doped. The drive-in temperature (800-950?°C) can be used to adjust the actual doping concentration in the range 2 × 10(18) to 10(20) cm(-3). Furthermore, we have fabricated NMOS and PMOS devices to show the versatility of this approach and the possibility of achieving segmented doping of NWs. The devices show high I(on)/I(off) ratios of around 10(7) and, especially for the PMOS, good saturation behavior and low hysteresis.     

Nanoporous,bioactive and cytocompatible TiO2 encapsulated Ti particles as bone augmentation material

Bone impaction grafting is a surgical technique used for the restoration of bone stock loss with impaction of autograft or allograft bone particles. Porous Ti particles are deformable, like bone particles, and offer better primary stability. In this study, spherical Ti particles were subjected to H₂O₂ solution treatment at 70 °C for 3 h and heat treated at different temperatures in the range of 400–800 °C. FE-SEM observation showed that Ti particle form highly porous network structure and these porous network structures were confirmed to be hydrogen titanate by Raman analysis. Subsequent heat treatment at temperature ranges of 400–800 °C showed the gradual transformation of hydrogen titanate network to anatase and finally rutile phase of TiO₂. The network structure appeared to be compacted by the heat treatment due to water removal and ultimately take the particulate morphology above 800 °C. Thus formed TiO₂ encapsulated Ti particles showed bioactivity in terms of deposition of apatite layer from simulated body fluid in the range of 400–600 °C. The cytocompatibility studies using osteoblast-like cells, MG63 showed good cell viability as well as adhesion for all Ti particles. Present results indicates that bioactive TiO₂ encapsulated Ti particles could be a candidate material to be useful as bone or dental cavity filler or bone cement for total hip replacement materials.