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Belhadi A.,University of Science and Technology Houari Boumediene | Nadjem I.,University of Science and Technology Houari Boumediene | Zaidat S.,University of Science and Technology Houari Boumediene | Boudjemaa A.,University of Science and Technology Houari Boumediene | And 2 more authors.
International Journal of Energy Research | Year: 2015

The semiconducting properties of the heterojunction CuO/ZnO, synthesized by impregnation method from nitrates, are studied for the first time to assess its feasibility for the hydrogen production under visible light, an issue of energy concern. CuO exhibits a direct optical transition at 1.33eV, due to Cu2+: 3d orbital splitting in octahedral site, and possesses a chemical stability in the pH range (4-14). The Mott-Schottky plot in (Na2SO4, 0.1M) medium indicates p-type conduction with a flat band potential of 0.70VSCE and a holes density of 1.35×1017cm-3. As application, hydrogen evolution upon visible light is demonstrated on the heterojunction ×%CuO/ZnO (x=5, 10 and 20wt.%). The best performance occurs at pH ~12 with an evolution rate of 4.8cm3min-1 (gcatalyst)-1 and a quantum yield of 0.12%. The improved activity is attributed to the potential of the conduction band of CuO (-1.34VSCE), more negative than that of ZnO, the latter acts as electrons bridge to water molecules. The presence of SO3 2- reduces the recombination process, thus resulting in more H2 evolution. © 2015 John Wiley & Sons, Ltd.


Boudjemaa A.,Research Center in Analytical Chemistry and Physics | Trari M.,University of Science and Technology Houari Boumediene | Bachari K.,Research Center in Analytical Chemistry and Physics
Environmental Progress and Sustainable Energy | Year: 2014

Iron-substituted mesoporous silica, Santa Barbara Amorphous (Fe-SBA-15) molecular sieve with Si/Fe ratio of 50 is prepared by microwave-hydrothermal method. The photoelectrochemistry reveals a metal deficiency and the oxide exhibits P type conductivity with activation energy of 20 meV. The flat band potential, determined from the capacitance measurements, is found to be -0.61 VSCE. Hence, the conduction band, made up of 3d orbital (∼4 eV), permits a good position of H2O/H2 level (-0.88 V/SCE), thus allowing a thermodynamically feasible H2 liberation under visible light. In neutral medium, the photocatalyst shows a high H2 evolution with a rate of 115 μmol g-1 min-1 in presence of SO3 2- as hole scavenger. The initial performance of the PEC system is restored when the solution is bubbled with nitrogen, a deactivation effect of <2% is observed. © 2013 American Institute of Chemical Engineers.


Boudjemaa A.,Research Center in Analytical Chemistry and Physics | Bachari K.,Research Center in Analytical Chemistry and Physics | Trari M.,University of Science and Technology Houari Boumediene
Materials Science in Semiconductor Processing | Year: 2013

We describe in the present work the photo-electrochemical characterization of iron/folded-sheets mesoporous materials (Fe-FSM-16, Si/Fe=60) synthesized by microwave-assisted hydrothermal (M-H) method and its application for the hydrogen evolution upon visible light. The mesoporous catalyst consists of small Fe2O3 particles (∼2 nm) spread on SiO2 with specific surface area of ∼800 m2 g-1. The capacitance measurements reveal an iron deficiency and the oxide exhibit p type conductivity with activation energy of 0.07 eV. The optical gap of the hematite (α-Fe2O3) is evaluated at 3.24 eV from the diffuse reflectance spectrum. The flat band potential Vfb (-0.54 V SCE) and the holes density ND (9.56×1014 cm-3) of the hematite are obtained respectively by extrapolating the linear part to C-2=0 and the slope of the Mott Schottky plot. At pH=7, the conduction band (-0.47 VSCE) is suitably positioned with respect to the H2O/H2 level (-0.59 VSCE) leading to a spontaneous water reduction. The oxide is stabilized by hole consumption involving SO32- and S2O 32- species and spectacular improvement of the hydrogen evolution is reported with evolution rates of ∼461 and 163 μ mol respectively. © 2013 Elsevier Ltd. All rights reserved.


Touahra F.,Research Center in Analytical Chemistry and Physics | Touahra F.,University of Science and Technology Houari Boumediene | Rabahi A.,Research Center in Analytical Chemistry and Physics | Chebout R.,Research Center in Analytical Chemistry and Physics | And 5 more authors.
International Journal of Hydrogen Energy | Year: 2016

Perovskite oxide LaCuO3 and LaCu0.53Ni0.47O3 were prepared using the sol-gel citrate method, whereas 5% NiO/LaCuO3 was prepared by impregnation. The products obtained, after heat treatment under air at 800 °C, were characterized by several techniques such as: thermogravimetric analysis (TG), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), Brunauer-Emmett-Teller method (BET) and temperature programmed reduction (TPR). After reduction, the catalysts were evaluated in the reforming of methane reaction under continuous flow with CH4/CO2 ratio equal to 1, at atmospheric pressure and a temperature range [500-700 °C]. The catalytic activity was tested in a fixed bed reactor. At 700 °C, the amount of CH4 consumed was in its lowest in the presence of LaCuO3 whereas the amount of CH4 conversion increased to 60% in case of LaCu0.53Ni0.47O3 precursor. The best results were obtained using 5% NiO/LaCuO3 precursor, whereby the amount of CH4 consumed augmented by 16.5% compared to that of LaCu0.53Ni0.47O3. Copyright © 2015 Hydrogen Energy Publications, LLC.


Boudjemaa A.,Research Center in Analytical Chemistry and Physics | Boudjemaa A.,University of Science and Technology Houari Boumediene | Bachari K.,Research Center in Analytical Chemistry and Physics | Bachari K.,University of Science and Technology Houari Boumediene | Trari M.,University of Science and Technology Houari Boumediene
International Journal of Energy Research | Year: 2013

The iron hexagonal mesoporous silica (Fe-HMS)-n photocatalyst, where n is the molar ratio Si/Fe in the precursor gel (=50), has been successfully synthesized at an ambient temperature using hexadecylamine as template agent. The material was characterized by X-ray diffraction, N2 adsorption measurement Brunauer, Emmet, Taller (BET) and Barrett-Joyner-Halenda theory, UV-Vis spectroscopy, high-resolution transmission electron microscopy and electron spin resonance. The electrical conductivity follows an Arrhenius-type law with activation energy of 0.04eV. Fe2O3 is uniformly dispersed on the HMS surface; it works synergistically to make Fe-HMS photoelectrochemically active. The flat band potential (-0.75VSCE) is higher than the potential of hydrogen generation (-0.50VSCE at pH~7), and the material shows high efficiency for hydrogen evolution upon visible light. The photoactivity in Na2SO4 and Na2SO3 (0.1M) solution was found to be 136 and 175μmolg-1min-1, respectively under full light (29mWcm-2). The tendency to saturation, observed only in SO3 2- electrolyte, is ascribed to the competitive reduction of the end product, namely S2O6 2- with the water reduction. © 2011 John Wiley & Sons, Ltd.

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