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 ...

A series of novel cationic gemini surfactants with diethylammonium headgroups and a diamido spacer were synthesized, and their surface and bulk properties were investigated by surface tension, electrical conductivity, fluorescence, viscosity, dynamic light scattering (DLS), and transmission electron microscopy (TEM) measurements. An interesting phenomenon, that is, the obvious decline in surface tension upon increasing concentration above the critical micelle concentration (cmc), was found in these gemini surfactant solutions, and two explanations were proposed. This surface tension behavior could be explained by the rapid increase in the counterion activity in the bulk phase or the continued filling of the interface with increasing surfactant concentration above the cmc. More interestingly, not only vesicles but also the surfactant-concentration-induced vesicle to larger aggregate (spongelike aggregate) transition and the salt-induced vesicle and spongelike aggregate to micelle transition were found in the aqueous solutions of these gemini surfactants. The spongelike aggregate that is first reported in the cationic gemini surfactant-water binary system is probably caused by the adhesion and fusion of vesicles at high surfactant concentration.

No abstract

No abstract

A series of polyaniline (PANI) salts were synthesized with the presence of a small amount of water varying from 0 to 1 mL at the beginning of solid-state polymerization. The structure and morphology of the samples were characterized by fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-Vis) absorption spectra, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical performances of the products were investigated by galvanostatic charge-discharge, cyclic voltammetry, cycling stability and electrochemical impedance spectroscopy (EIS). The results showed that the amounts of water can affect the oxidation degree, conjugate level and crystallinity of PANI salts. All PANI salts showed spherical morphology with the diameter of about 60 nm as shown by TEM. The electrochemical tests showed the highest specific capacitance value 593.3 F.g−1 in 1 M H2SO4 for PANI prepared with the addition of 0.5 mL of water at the beginning of solid-state polymerization.

No abstract

Ellipsometry and surface profile analysis tensiometry were used to study and compare the adsorption behavior of beta-lactoglobulin (BLG)/C10DMPO, beta-casein (BCS)/C10DMPO and BCS/C12DMPO mixtures at the air/solution interface. The adsorption from protein/surfactant mixed solutions is of competitive nature. The obtained adsorption isotherms suggest a gradual replacement of the protein molecules at the interface with increasing surfactant concentration for all studied mixed systems. The thickness, refractive index, and the adsorbed amount of the respective adsorption layers, determined by ellipsometry, decrease monotonically and reach values close to those for a surface covered only by surfactant molecules, indicating the absence of proteins from a certain surfactant concentration on. These results correlate with the surface tension data. A continuous increase of adsorption layer thickness was observed up to this concentration, caused by the desorption of segments of the protein and transforming the thin surface layer into a rather diffuse and thick one. Replacement and structural changes of the protein molecules are discussed in terms of protein structure and surface activity of surfactant molecules. Theoretical models derived recently were used for the quantitative description of the equilibrium state of the mixed surface layers.

Polyaniline/Cu(0.05)Zn(0.95)O (PANI/CZO) nanocomposites were prepared by in situ inverse microemulsion method. Based on the characterization of the crystal structure, chemical composition, and morphology of the samples, it was confirmed that CZO nanoparticles were incorporated into the polyaniline matrix. Studies of the antimicrobial activities of the samples against Staphylococcus aureus, Escherichia coli and Candida albicans were carried out using powder inhibition zone, minimum inhibitory concentration and minimal bactericidal concentrations methods. The results showed clearly that, as an antibacterial agent, PANI/CZO nanocomposites exhibited excellent antibacterial activity against the growth of microorganisms. Furthermore, the antibacterial mechanism of the samples was also deduced in this paper.