Synergistic effects of FeCl₃-derived deoxygenation and pore formation on TiFe hydrogen storage alloys

TiFe hydrogen storage alloys possess the merits of abundance on earth and availability at ambient temperature in ever-growing applications but suffer from the challenge of complicated activation. Herein, FeCl 3 , which has synergistic effects of deoxygenation and pore formation, is reported to address this issue. For one thing, the production of oxygen vacancies and weakened Ti O interactions in TiFe alloys accelerate hydrogen absorption. For another, tailored defects fabricated by FeCl 3 , such as pores and cracks, harmoniously facilitate hydrogen transportation. Consequently, it enables the oxygen content of the sintered TiFe alloy to be as low as 0.29 wt%, which delivers a marvelous hydrogen absorption capacity of 1.67 wt% at 25 °C almost without incubation. The deoxygenation mechanism and influence of the pore-forming effect on microstructure and hydrogen storage performance are unambiguously elucidated by atomic-scale characterizations and theoretical calculations. This work proposes deep insights into the hydrogenation kinetics mechanism of the up-to-date TiFe alloys and provides promising prospects to synthesize the high-performance and low-cost solid-state hydrogen storage materials.