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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 a nucleation and growth model. The activation energy is in the range 43‐52 kJ/mol and the rate constant (at 150 °C) increases from 27∙[10]^(‐3) s‐1 to 92∙[10]^(‐3) 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 ~32 kJ/mol. The rate constant (at 150 °C) increases from 0.5∙[10]^(‐3) s‐1 to 1.2∙[10]^(‐3) s‐1 with the Ti content. These results open an …
Publication date: 
6 Feb 2019

Nicola Patelli, Andrea Migliori, Luca Pasquini

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