Mechanical alloying to fabricate Mg10Co for the enhanced hydrogenation performance
MgCo alloys are considered important hydrogen storage materials, yet it depends on the synthetic methods (alloying, nanosizing, catalyst modification, etc ) to a certain degree. Thus, investigation of the effect of synthetic conditions on the dynamics/thermodynamic properties of MgCo alloys is a crux. Herein, we fabricated Mg10Co alloy via a combination of mechanical alloying and high-temperature/pressure hydrogenation to explore the effect of alloying time on the hydrogenation and dehydrogenation performances of Mg10Co. The Mg10Co consists of Mg, Mg 2 Co, MgCo 2 , and Co phase, providing nucleation sites for heterogeneous nucleation of hydrides, and the grain refinement can increase surface defects, shorten the diffusion and transport distance of hydrogen. In addition, the ball milling time significantly affected the hydrogenation performance, and the best performance was achieved with the ball milling time being 14 h, and Mg10Co can absorb 5.93 wt% of H 2 in 5 min at 350 °C. The high hydrogen absorption rate can perhaps due to the lower absorption plateau of Mg 2 CoH 5 and Mg 6 Co 2 H 11 hydrides relative to MgH 2 . Furthermore, the dehydrogenation activation energy was 124.89 kJ/mol. This work contributes to the improvement of the kinetics properties of magnesium-based hydrogen storage alloys.
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