Understanding first cycle hydrogenation properties of Ti-Fe-Zr ternary alloys

Abstract

Zirconium has been used as an alloying element to mitigate the difficulty in the initial hydrogenation of pristine TiFe, a room-temperature hydrogen storage material. The addition of zirconium induces the formation of AB(2)-type ternary phases such as tau 1 and tau 3. In this study, these ternary phases were produced individually and their activation kinetics and hydrogen storage properties were assessed. Ultimately, both tau 1 and tau 3 can be activated at room temperature under hydrogen at a pressure of 3 MPa. The result validates the presumption that Zr-added TiFe is easily activated with the help of the Ti-Fe-Zr ternary phases. In addition, they can store 1.8-1.9 wt% of hydrogen, which proves their own use as a hydrogen storage material. The easy activation may be caused by the compositional inhomogeneity of mixed metal oxide at the alloy surface, as revealed by depth-profiling X-ray photoelectron spectroscopy; this provides new reaction pathways for hydrogenation. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.