In-Situ TEM Observation for Dehydrogenation Mechanismin MgH_2 with Catalyst

摘要

We carried out in-situ observation on the catalytic effect of Nb_2O_5in MgH_2by using a highvoltage transmission electron microscope (HVEM). We synthesized two kinds of samples, whichwere prepared by ball milling and by hand mixing. In milled sample, Nb_2O_5was not confirmed fromhigh resolution images, however, NbO was identified. As the temperature increased, thedecomposition of MgH_2proceeded, while Mg formed and grew. It suggested that NbO had thecatalytic effect to promote the dehydrogenation of MgH_2. In mixed sample, which was prepared toclearly observe the boundary between the catalyst and Mg phase, it was revealed that thedehydrogenation started from the boundary of MgH_2and Nb_2O_5. This result suggested that thedehydrogenation could proceed with hydrogen diffusion from MgH_2through Mg phase to theboundary.