Synergetic effect of Ni and Nb2O5 on dehydrogenation properties of nanostructured MgH2 synthesized by high-energy mechanical alloying |
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| Authors: | Hamed Simchi A Kaflou A Simchi |
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| Affiliation: | aDepartment of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran, Iran;bInstitute for Advanced Materials and Renewable Energy, Iranian Research Organization for Science and Technology, P.O. Box13135-115, Tehran, Iran;cInstitute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran, Iran |
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| Abstract: | Nanostructured MgH2-Ni/Nb2O5 nanocomposite was synthesized by high-energy mechanical alloying. The effect of MgH2 structure, i.e. crystallite size and lattice strain, and the presence of 0.5 mol% Ni and Nb2O5 on the hydrogen-desorption kinetics was investigated. It is shown that the dehydrogenation temperature of MgH2 decreases from 426 °C to 327 °C after 4 h mechanical alloying. Here, the average crystallite size and accumulated lattice strain are 20 nm and 0.9%, respectively. Further improvement in the hydrogen desorption is attained in the presence of Ni and Nb2O5, i.e. the dehydrogenation temperature of MgH2/Ni and MgH2/Nb2O5 is measured to be 230 °C and 220 °C, respectively. Meanwhile, the dehydrogenation starts at 200 °C in MgH2–Ni/Nb2O5 system, revealing synergetic effect of Ni and Nb2O5. The mechanism of the catalytic effect is presented. |
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| Keywords: | Metal hydrides Nanostructures Hydrogen absorbing materials Mechanical alloying Microstructure |
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