Exchange interaction between localized magnetic moments mediated by free charge carriers is responsible for a non-monotonic dependence of the low-temperature energy band-gap in dilute magnetic semiconductors. We found that in weakly doped Mn-ZnO films, increasing the exchange interaction by increasing the concentration of free charge carriers results in a red-shift of the nearband-edge emission peak at room temperature. An increase of Mn concentration widens the band gap, and a blue-shift prevails. Exchange interaction can be used to tune the room-temperature optical properties of the wide-band gap semiconductor ZnO. V

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The inhibition of zinc corrosion in 3.5% NaCl solution by some organic compounds (sodium dodecylsulphate (SDS), sodium dodecylbenzosulphonate (SDBS) and sodium 1,4-bis(2-etylhexyl) sulphosuccinate (AOT)) was investigated. The inhibition efficiencies were determined by polarization measurements of the zinc electrode in the solution. Electrochemical impedance spectroscopy (EIS) was also used for electrochemical studies of zinc electrode in this medium. The results showed that the used surfactants inhibit the cathodic reaction of hydrogen evolution and at low anodic overvoltage the corrosion process is under activation control, while at high anodic overvoltage the process is under diffusion control.

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This article reports an amperometric glucose biosensor based on a new type of nanocomposite of polypyrrole (PPY) with p-phenyl sulfonate-functionalized single-walled carbon nanotubes (SWCNTs-PhSO3−). An environmentally friendly functionalization procedure of the SWCNTs in the presence of substituted aniline and an oxidative species was adopted. The nanocomposite-modified electrode exhibited excellent electrocatalytic activities towards the reduction or oxidation of H2O2. This feature allowed us to use it as bioplatform on which glucose oxidase (GOx) was immobilized by entrapment in an electropolymerized PPY/SWCNTs-PhSO3− film for the construction of the glucose biosensor. The amperometric detection of glucose was assayed by applying a constant electrode potential value necessary to oxidize or reduce the enzymatically produced H2O2 with minimal interference from the possible coexisting electroactive compounds. With the introduction of a thin film of Prussian blue (PB) at the substrate electrode surface, the PPY/GOx/SWCNTs-PhSO3−/PB system shows synergy between the PB and functionalized SWCNTs which amplifies greatly the electrode sensitivity when operated at low potentials. The biosensor showed good analytical performances in terms of low detection (0.01 mM), high sensitivity (approximately 6 μA mM−1 cm−2), and wide linear range (0.02 to 6 mM). In addition, the effects of applied potential, the electroactive interference, and the stability of the biosensor were discussed. The facile procedure of immobilizing GOx used in the present work can promote the development of other oxidase-based biosensors which could have a practical application in clinical, food, and environmental analysis.

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Single-crystal ZnO nanowires long up to several microns were fabricated by one-step electrochemical deposition. A template-based process employing track-etched polycarbonate (TE-PC) membranes was used for this purpose. The morphology and the structure characteristics of the ZnO nanowires were analyzed by means of Scanning Electron Microscopy (SEM), Focused Ion Beam (FIB), Transmission Electron Microscopy (TEM), and Selected Area Electron Diffraction (SAED). The growth process conditions turned out to have a marked influence on the crystal nature and morphology of the nanowires. Deposition rates ranging from 0.4 nm s −1 and up to 0.6 nm s −1 were recorded for the growth of ZnO nanowires. The obtained results showed that by using carefully controlled deposition conditions single crystalline nanowires and fine-grained structures can be routinely obtained. ZnO has extrusive physical properties such as a direct bandgap in the ultraviolet range (3.37 eV) or a large exciton binding energy (60 meV) which have made it a great application prospect.1, 2 ZnO nano-objects have been widely investigated in the recent years owing to promising applications in nanodevices. They showed high sensitivity to different chemicals, have piezo-and pyro-electric properties, etc. 3,4 As it has been shown that band edge, exciton energies, and UV luminescence of ZnO nanostructures are affected by crystallite size and crystal morphology, 5,6 it is desirable to tailor their electronic properties in order to exploit the broad range of applications.Nowadays, many efforts still focus on synthesizing oriented onedimensional ZnO nanostructures. Up to now, techniques using sophisticated and expensive equipments but also low temperature and cost-effective methods such as electrodeposition (ED) and hydrothermal deposition were employed for the synthesis of nanostructures. 7-9The major advantage of the electrochemical synthesis is given by its application for large area and high throughput productions, therefore suitable for an industrial use. [10][11][12][13] The ED of ZnO nanowires has been focused mostly on the preparation of nanorod/nanowire arrays by the template method and on flat substrates. 14, 15The ZnO electrodeposition is based on the reduction of an oxygen precursor such as dissolved molecular oxygen, nitrate ions or hydrogen peroxide. For example, Cembrero et al. 16 reported on the cathodic electrodeposition of ZnO nanocolumns and nanowires from zinc chloride solutions saturated in molecular oxygen. The general scheme for ED of ZnO employing different oxygen precursors is supposed as follows.The reaction at the cathode surface employing different oxygen precursors: The process evolves itself drifting the pH of the electrolyte to a constant increase and to a local supersaturation of the bath in the vicinity of the electrode, thus provoking the precipitation on the electrode surface of ZnO;18 therefore, if a specific crystal order is desired, the pH of the electrolytic solution has to be precisely controlled and adjusted to a proper value.As...