Hydrogen sorption and desorption kinetics and hydrogenation stability of Mg-metal-hydride thin films

The intermetallic compounds of Mg with Al, Fe, V, Ti and Zn were investigated concerning their hydrogenation and dehydrogenation behavior by near infrared optical measurements. Pd-capped Mg-metal thin films were prepared by RF magnetron sputtering. Since Pd is a hydrogen catalyst, Mg-metal compounds can be loaded with hydrogen at room temperature by exposure to hydrogen containing gas. They act as hydrogen-induced switching mirrors which switch from a shiny, metallic to a transparent appearance. However, the durability of repetitive hydrogenation emerged to be a major issue, since the hydrogen sorption is suppressed due to the forming of an Mg-Pd alloy at the interface through Mg diffusion. The sorption and desorption kinetics and durability could be significantly improved by inserting a metal buffer layer consisting of Nb, V, Ta, or Ti between the Pd and the Mg-metal compound. (C) 2013 Elsevier B.V. All rights reserved.