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    ABSTRACT: In this paper, we report on the time-dependent development of cupric oxide films by chemical modifica-tion of copper substrates submerged horizontally in a room temperature 75 mmol/L ammonia solution at pH 11, over a period of nine days. Morphological and structural characterization of the oxide-substrate tandems were carried out by SEM–EDX and XRD, while the relative directional spectral absorptivity and reflectivity were determined by Vis–NIR spectrometry. The ageing process, controlling both the color and morphological structure of the predominately amorphous-CuO/Cu, has positively contributed to the enhancement of spectral absorptivity, while band gap values evolve from 1.29 to 1.39 eV for exposure times from 36 to 168 h. Ó 2014 Elsevier B.V. All rights reserved.
    Journal of Alloys and Compounds 12/2014; 617(C):542-546. DOI:10.1016/j.jallcom.2014.07.221 · 2.73 Impact Factor
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    ABSTRACT: An easy synthesis route for cuprous oxide (Cu2O) nanoparticles is reported via thermal annealing improved and controlled by in-situ conductivity measurements. The crystalline structure, phase transition, surface morphology and particle size/shape, were investigated through X-ray diffraction, a conductivity setup and scanning electron microscopy, respectively. X-ray diffraction patterns revealed that initial metallic Cu nanoparticles were transformed to Cu2O nanoparticles with high purity, under specific conditions critically dependent on the temperature and annealing duration. This transformation was also dependent on the film thickness and atmospheric composition in the test chamber during the annealing process.
    Ceramics International 07/2014; 40(6). DOI:10.1016/j.ceramint.2013.12.130 · 2.09 Impact Factor
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    ABSTRACT: Overall decomposition of water into hydrogen and oxygen in presence of a heterogeneous photocatalyst has received prodigious attention due to its potential for the production of clean and recyclable hydrogen energy. However, most of the efficient photocatalysts developed till date, works primarily on ultra-violate range of light. To develop photocatalysts that can decompose water under more abundant visible range of light, efforts have already been made by researchers who basically tried to synthesize materials which have such a narrow band gap that they can utilize less energetic photons in visible range. To do so, the catalysts that they have prepared to exhibit high stability and to give decent reaction rate and quantum efficiency are of extremely complex structure. Moreover, cumbersome synthesis route involving doping of different materials, complicated core-shell nanostructure preparation, etc is necessary in most of the cases. Here, we report a facile and efficient approach to facilitate photocatalytic water-splitting under visible light, in single step. We have modified Cu2O, a well-known p-type semiconductor having a band-gap ∼2.1 eV, with RuO2 nanoparticles and used it as photocatalyst. We have observed that it has a possibility of near-stoichiometric overall water decomposition under visible light with appreciable quantum efficiency.
    Energy Procedia 01/2014; 54:221–227. DOI:10.1016/j.egypro.2014.07.265

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