Non-isothermal desorption process of hydrogenated nanocrystalline Pd-capped Mg films investigated by Ion Beam Techniques

• Published in: International journal of hydrogen energy Vol. 39; no. 6; pp. 2587 - 2596
• Main Authors: Ares, J.R., Leardini, F., Díaz-Chao, P., Ferrer, I.J., Fernández, J.F., Sánchez, C.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 14.02.2014; Elsevier
• Subjects: Activation energy; Alternative fuels. Production and utilization; Applied sciences; Decomposition reactions; Desorption; Deuteration; Energy; Exact sciences and technology; Fuels; Hydrides; Hydrogen; Hydrogen storage; Ion Beam Techniques; Magnesium; Magnesium hydride; Nanocrystalline film; Nanocrystals; Palladium; Thermal desorption mechanism; Hydrogen storage; Thermal desorption mechanism; Magnesium hydride; Ion Beam Techniques; Nanocrystalline film; Hydrogen; Desorption; Palladium
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2013.11.130

Nanocrystalline Pd-capped Mg films were prepared by e-beam evaporation and hydrided/deuterated in order to investigate the hydride decomposition mechanism. To that aim, different techniques were used (XRD, FEG, TPD–MS, isotope exchange and “in situ” desorption optical measurements). Obtained results show that hydride films decomposed at T = 165 °C by a process controlled by the Mg/MgH2 interface reaction with an activation energy Ea = 136 ± 5 kJ/mol H2. Interface is located into each MgH2 nanocrystallite according to RBS (Rutherford Backscattering) and ERDA (Elastic Recoil Detection Analysis) measurements performed during hydride decomposition. Moreover, RBS and ERDA spectra also show the formation of a MgxPdy intermixed region. This intermixed region does not modify the type of control mechanism but increases the activation energy of the desorption process and slows down further hydrogenation events. •H-desorption is governed by the two-dimensional Mg/MgH2 interface migration.•RBS and ERDA measurements show that interface occurs at each MgH2 nanocrystallite.•Spontaneous formation of Mg/Pd intermixed region is observed during H-desorption.•Intermixed region precludes the H-desorption by increasing the Ea of the migration.