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Abstract—: This paper presents a systematic Raman scattering study of novel nanostructured materials based on synthetic opal and Bi2TeO5 nanocrystals, which offer high photorefractive sensitivity. Bismuth tellurite was introduced into opal pores in a molten state. The crystal structure of the material in the opal pores was determined by Raman spectroscopy. Comparison of the measured Raman spectra of the opal-Bi2TeO5 nanocomposite and those of polycrystalline powders and single crystals made it possible to reveal a number of new bands and analyze their origin. The observed variation in the intensity of Raman bands from point to point on the sample surface can be interpreted as due to structural light focusing and excitation field localization at surface and volume defects of the photonic crystal structure of the material. [ABSTRACT FROM AUTHOR]

Synthetic opals composed of 300 nm silica spheres are impregnated with a Bi12SiO20 melt at 1190 K. Structure and properties of the as-prepared samples are studied by employing the scanning electron microscopy, X-ray diffraction, and optical spectroscopy and direct current conductivity techniques. The nanocomposites are found to be multi-phase systems composed of Bi12SiO20, Bi4Si3O12 and SiO2 crystallites with an average linear size not less than 20 nm. Formation of Bi4Si3O12 crystallites becomes possible as a result of changing in the Bi2O3-SiO2 molar ratio due to the melting of silica spheres. The Raman intensity redistribution observed by surface scanning may be caused by both composition inhomogeneity and concentration of the exciting radiation field at composite defects. The "red" shift of photoluminescence band is observed. Activation energy of direct current conductivity is estimated as 1.1 eV. [ABSTRACT FROM AUTHOR]

A Co-Ni oxide/vertically aligned carbon nanotube (VACNT) composite was prepared by thermal decomposition of cobalt-nickel nitrate precursor on the surface of VACNT electrode. VACNTs were used as 3D nanoporous substrate and were grown by plasma-enhanced chemical vapor deposition from a mixture of H2and C2H2. The specific capacitance of Co-Ni oxide (5:5)/VACNT (with equal Co+2/Ni+2mole ratio) was measured to be 1050 Fg−1, which is about 1.9- and 3-fold that of Ni oxide/VACNT (540 Fg−1) and Co oxide/VACNT (341 Fg−1), respectively. The results show Co-Ni oxide (5:5)/VACNT composite electrode has excellent specific capacitance because of porous network structure, good electrical conduction pathways, high access for the electrolyte solution, and consequently increased composite/solution interfacial contact area. The capacitance property of the Co-Ni oxide/VACNT composite electrode with different Co+2/Ni+2mole ratios was also investigated and the highest specific capacitance is achieved at equal Co+2/Ni+2mole ratio. [ABSTRACT FROM PUBLISHER]

Sol-gel films of tetraethoxysilane (TEOS), phenyltriethoxysilane (PTES) and phenyltrimethoxysilane (PTMS) were prepared on aluminium and aluminium alloy AA7075 and characterised. The corrosion inhibition properties of uncoated and coated specimens were evaluated with potentiodynamic polarisation scan, linear polarisation resistance and open circuit potential measurements. With scanning electron microscopy and optical microscopy effects of the sol-gel coating were shown. Weight loss measurements were performed at different pH-values. More hydrophobic coatings as PTMS show a considerably better corrosion inhibition capacity as compared to the capacity provided by less hydrophobic ones as TEOS and PTES. [ABSTRACT FROM AUTHOR]

Ultrathin mesoporous nanoflakes of α-MnO2 films were easily prepared by mixing potassium permanganate (KMnO4) with hydrochloric acid in an aqueous solution. The obtained α-MnO2 has a tunnel structure composed of an edge-shared network of [MnO6] octahedra. Scanning electron micrograph observations revealed that the obtained MnO2 materials have 2D frameworks which consisted of highly porous interconnected nanoflakes. TEM image shows that the ultrathin nanoflakes almost have the thickness about 3-5 nm. Nitrogen desorption analyses showed that these ultrathin MnO2 nanoflakes exhibited large surface area up to 102 m2g-1. The electrochemical performances of the synthesized α-MnO2 ultrathin nanoflakes as supercapacitor electrode materials were studied by cyclic voltammetry cycling in 1 M Na2SO4 solution. The result showed that mesoporous MnO2 with 2D frameworks exhibit a high capacitance of 328 Fg-1 with 84 % stability for 1000 cycles. Thus, the obtained ultrathin α-MnO2 nanoflakes are suitable for its use as supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]

An aqueous rechargeable lithium battery (ARLB) using an electroactive polymer, polypyrrole (PPy), as a negative electrode; a lithium ion intercalation compound LiCoO2 as a positive electrode; and Li2SO4 aqueous solution as an electrolyte and its working mechanism are described. The charge/discharge process is associated with the doping/un-doping of anions at the negative electrode and intercalation/deintercalation of lithium ions at the positive electrode. The average output voltage of the PPy//LiCoO2 battery is about 0.85 V. This battery exhibits excellent cycling performance. This new technology solves the major problem of poor cycling life of ARLBs and will provide a new strategy to explore advanced energy storage and conversion systems. [ABSTRACT FROM AUTHOR]

The article evaluates the primary electrochemical performance of surface modified spherical graphite in relation to the distribution of conductive additive particles on the coated electrode material. It has been observed that the cycling behavior was influenced by the dispersion of conductive additive. The initial reversible capacity was greater than that of commercial synthetic graphite. Also, poor dispersion produced numerous white deposits.

Mild oxidation of a natural graphite in an ammonium peroxydisulfate solution yields promising anode materials. X-ray photoelectron spectroscopy, FTIR spectroscopy, electron paramagnetic resonance, thermogravimmetry, differential thermal analysis, high resolution electron microscopy and surface area measurements provided results suggesting that oxidation eliminates some reactive structural defects in this graphite. In addition, the surface of natural graphite is recoated with a dense layer of oxides forming an effective passivating film to prevent the decomposition of electrolyte and the movement of graphene molecules along its a-axis. Consequently, its thermostability and the EPR signal increase. In addition, the numbers of nanosized pores and channels increases, which provide more inlets and outlets for lithium intercalation and deintercalation and more sites for lithium storage. As a result, the reversible lithium capacity and the coulombic efficiency in the first cycle increase significantly and the cycling behaviour improves markedly. The reproducibility of product properties can be well controlled, and this method is promising for industry. [ABSTRACT FROM AUTHOR]

The influence of the composition and the casting process upon the electrochemical corrosion of a selection of palladium-based alloys and non- precious metal alloys has been investigated in vitro using an electrochemical method. No influence of the casting process upon the corrosion resistance was observed with palladium-based alloys. Changes in the crystallographic structure effected by the different composition of the alloys were found, the casting process did not cause significant effects. With nickel-chromium alloys rather low corrosion stabilities were observed. [ABSTRACT FROM AUTHOR]

A survey of representative studies on the oxidation of mono- and polyhydric alcohols on gold and platinum electrodes is given, with a special attention to the reaction mechanisms and the effect of the molecular structure of these compounds on their electrocatalytic reactivity. [ABSTRACT FROM AUTHOR]

The article presents information on a study on rechargeable lithium ion batteries with nonaqueous electrolyte solutions. These batteries are used for consumer electronic devices including mobile phones and laptop computers. For the study, crystalline LiV3O8 was prepared in an appropriate molar ratio at 680 degree C and was cooled down slowly to room temperature. The combination of negative and positive electrodes of a rechargeable lithium battery in aqueous electrolytes is stated to be of importance for obtaining good electrochemical performance. It was found that the cycling performance of the aqueous rechargeable lithium battery (ARLB) system is not comparable with our other ARLB systems using positive electrodes.

The application of a simplified spectrometric setup to the investigation of the electrochemical double layer using polarization sensitive in situ infrared spectroscopy is described. As examples, the adsorption of carbon monoxide, thiocyanate, and cyanate at platinum electrodes are investigated. Results are compared with previously published data. Differences are explained in terms of different experimental conditions, they are not caused by differences between the employed methods. [ABSTRACT FROM AUTHOR]

The article announces the 90th birthday of Wolf Vielstich on June 18, 2013.

An electronic interface connecting the potentiostat of an electrochemical measurement system to a Fourier transform infrared (FTIR) spectrometer as used for in situ IR reflection absorption studies is described. It makes use of readily available components, is installed without any changes in the hardware of the spectrometer or the potentiostat, and allows fast and reliable spectroelectrochemical measurements. [ABSTRACT FROM AUTHOR]