Characterization of microstructure and surface oxide of Ti1.2Fe hydrogen storage alloy

Abstract

In this study, we investigated the microstructures, hydrogen absorption kinetics, and oxide layers of TiFe and Ti1.2Fe hydrogen storage alloys. Whereas the TiFe alloy has a single phase, the Ti1.2Fe alloy is composed of three phases: TiFe, Ti2Fe, and Ti4Fe. Under no thermal activation process, the TiFe alloy does not absorb hydrogen, though the Ti1.2Fe alloy starts to absorb hydrogen after 4 min of incubation time. From the XPS results, it is revealed that the Ti concentration in the oxide layer on the Ti4Fe phase is higher than that on the TiFe phase, indicating that the Ti concentration in the oxide layer would be important in improving hydrogen absorption kinetics. Based on these results, the hydrogen absorption kinetics could be improved by adjusting composition, enabling the formation of a Ti-rich oxide layer.