Reversible Metal-Hydride Transformation in Mg-Ti-H Nanoparticles at Remarkably Low Temperatures |
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Authors: | Nicola Patelli Dr Andrea Migliori Prof Luca Pasquini |
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Institution: | 1. Department of Physics and Astronomy, University of Bologna, viale Berti-Pichat 6/2, 40127 Bologna, Italy;2. Unit of Bologna, Institute for Microelectronics and Microsystems, National Research Council, via Gobetti 101, 40129 Bologna, Italy |
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Abstract: | We study the kinetics of hydrogen sorption in Mg-Ti-H nanoparticles prepared by gas phase condensation of mixed Mg-Ti vapors under a H2-containing atmosphere. Four samples with different Ti contents from 14 to 63 at.% Ti are examined in the 100–150 °C range. The hydrogen absorption kinetics coupled with the formation of MgH2 can be described by a nucleation and growth model. The activation energy is in the range kJ/mol and the rate constant (at 150 °C) increases from s?1 to s?1 with increasing Ti content. Hydrogen desorption is well modeled by a sequence of surface-limited and contracting-volume kinetics, except at the highest Ti content where nucleation and growth is observed. The activation energy of surface-limited kinetics is /mol. The rate constant (at 150 °C) increases from s?1 to s?1 with the Ti content. These results open an unexplored kinetic window for Mg-based reversible hydrogen storage close to ambient temperature. |
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Keywords: | hydrogen sorption kinetics magnesium nanoparticles titanium |
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