The physical and chemical properties of nanoscopic substances can be considerably different from the properties exhibited by the same materials in the bulk. Nanoscience and nanotechnology do not imply simply a miniaturization in size, but rather an in-depth revolution in physical concepts, systems design, materials synthesis, and manufacturing. [1,2] Numerous research groups in both academia and industry around the world are consciously increasing efforts towards designing and developing advanced materials with dimensions ranging from a few to several hundred nanometers. Recently, nanostructured electrode materials have attracted great interest, as they show better rates and capabilities than traditional materials. In nanostructured electrode materials, the distance within the material over which electrolyte must transport ions is dramatically smaller compared with conventional electrodes composed of chemically similar bulk materials. In addition, larger surface areas in these materials lead to higher current densities during charge and discharge compared with conventional electrodes. [3,4] Thus, these characteristics have significant implications with respect to energy-storage devices based on electrochemically active materials (such as batteries and, especially, supercapacitors).[5±7]Electrochemical capacitors combining the advantages of dielectric capacitors, which can deliver high power within a very short time, and rechargeable batteries, which can store high amounts of energy, have found an increasingly important role in power-source applications such as hybrid electric vehicles, short-term power sources for mobile electronic devices, etc.[8]From a materials point of view, there are three main categories of electrochemical capacitors: carbon/carbon, metal oxide, and electronically conducting polymer. [9,10] Even though noble-metal oxides or hydrous oxides (i.e., ruthenium oxides) and carbon nanotubes yield remarkably high specific capacitances and/or power densities, capacitors based on these materials are much more costly than other technologies.[11±14]Conducting-polymer capacitors have been reported to display high power densities, but their specific capacitances are much lower than that of carbon/carbon and metal-oxide capacitors. Thus, developing alternative electrode materials with improved characteristics and performance is the next logical step. In this communication, we report a strategy to prepare a composite material of cobalt hydroxide on ultra-stable Y zeolite (USY) molecular sieves (designated Co(OH) 2 /USY) and, for the first time, we report its applications as a novel electrochemical capacitor. Our strategy is to use a high-surface-area USY zeolite as the template on which a redox-active Co(OH) 2 inorganic nanostructure is synthesized through ion exchange, chemical precipitation, and self-directed growth processes. We demonstrate that the unique structure of the nanocomposite, consisting of a loose whisker-like Co(OH) 2 phase on the order of~10 nm providing high electrochemical accessibility ...

MnO 2 hollow spheres and hollow urchins are synthesized via a simple hydrothermal process without using any template or organic surfactant. The effect of the reaction time on the microstructure and morphology of samples is observed systemically. Meanwhile, the forming mechanism of hollow-structured R-MnO 2 is carefully investigated by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The results of nitrogen adsorption-desorption experiments and electrochemical measurements show that the product obtained by hydrothermal reaction for 6 h has large specific surface area, uniform pore-size distribution, and excellent capacitance performance, which make it have a potential application as a supercapacitor electrode material.

Electrodeposited Ni(OH)(2) on nickel foam with porous and 3D nanostructures has ultrahigh capacitance in the potential range -0.05-0.45 V, and a maximum specific capacitance as high as 3152 F g(-1) can be achieved in 3% KOH solution at a charge/discharge current density of 4 A g(-1).

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Transurethral enucleation and resection of the prostate appears to be the modern alternative to transurethral resection of the prostate and open prostatectomy for bladder outlet obstruction due to benign prostatic hyperplasia. It may be done in glands up to 250 gm.

We describe here a new method for labeling the defects of single-walled carbon nanotubes (SWNTs) using TiO2 nanoparticles as markers. SWNTs were prepared by chemical vapor deposition, and dilute nitric acid (2.6M) oxidation was used to introduce carboxylic acid groups at the defect sites. Characterization of the SWNTs using ultrastructural and spectroscopic analyses was carried out following introduction of TiO2 nanoparticles. The results indicated that TiO2 nanoparticles were chemically absorbed at SWNT defect sites via an ester-type linkage between carboxylic acid groups at the defect sites and hydroxyl groups at the surface of the TiO2 nanoparticles. In addition, the adsorption behavior of TiO2 nanoparticles on SWNTs was determined following oxidization of the SWNTs using different processes. The results indicated that gas-phase oxidation introduces very few defect sites as evidenced by the low adsorption density of TiO2 nanoparticles. Refluxing in dilute nitric acid can be considered as a mild oxidation for SWNTs, affecting only those defects already present and causing no further damage. In contrast, sonication of SWNTs in H2SO4/H2O2 increased the incidence of carboxylic acid groups, not only at original defect sites but also at newly created defect sites along the walls of SWNTs, resulting in a higher density of TiO2 nanoparticles. In conclusion, labeling of SWNT defect sites using TiO2 nanoparticles permits direct determination of the density, distribution, and location of the defects and offers new possibilities for the creation of heterojunctions between nanotubes and nanoparticles in the future.

A TiO 2 nanotube was prepared by a hydrothermal process. Transmission electron microscope tests showed that the products are uniform straight hollow tubes with the diam around 8 nm and the length over 300 nm. X-ray diffraction measurements indicate that the nanotubes crystallized in anatase TiO 2 . Cyclic voltammetry and galvanostatic charging and discharging tests showed that lithium-ion intercalation/deintercalation occured reversibly in the TiO 2 nanotube electrode, and a high capacity can be obtained. Electrochemical impedance spectra show that Li ϩ ion intercalation occurs below 2.2 V. Around the 1.7 V plateau, the total electrochemical resistance reached a minimum.