Nanostructured Mg for hydrogen production by hydrolysis obtained by MgH₂ milling and dehydriding

The synthesis, characterization and hydrolysis properties of nanostructured MgH2 and Mg in a 0.6 M MgCl2 aqueous solution are reported. The microstructural properties of commercial MgH2 are modified by mechanical milling without additives under H-2 atmosphere for 5 h. The nanostructured Mg is obtained by dehydriding the as-milled MgH2 under vacuum at 355 degrees C for 2.5 h. The as-milled MgH2 shows average hydrolysis properties with good hydrogen production capacity (1390 mL/g H-2) and kinetics (50% of the total yield in 2.3 min). The nanostructured Mg exhibits excellent hydrolysis properties with a high yield (910 mL/g H-2), fast kinetics (90% of the total yield in 2.6 min) and practically no effect of a MgO/Mg(OH)(2) passivating layer. The hydrolysis properties of both materials are attributed to their morphology and microstructure. The activation energies of the reaction are estimated and the mechanisms are discussed. (C) 2020 Elsevier B.V. All rights reserved.