Tuning of Zr content in TiMn2 based multinary alloys by powder metallurgy to fabricate superior hydrogen storage properties.

Abstract

TiMn₂ based multinary alloys make full use of the high abundance of rare earth resources in attractive applications of hydrogen storage but suffer from mediocre hydrogen ab/desorption kinetics and lack the in-depth mechanism analysis of hydrogenation/dehydrogenation behavior. Herein, on the basis of current research on compositional modulation, we utilize the low-cost powder metallurgy method to prepare Ti_0.9+xZr_0.1-xMn_1.4Cr_0.4V_0.2 (x = -0.05, 0, 0.05) hydrogen storage alloy powders, which effectively reduces the preparation cost. What's more, the fractional substitution of Zr for Ti boosts the hydrogenation by introducing defects and modulating the d-band center. The synthesized Ti_0.85Zr_0.15Mn_1.4Cr_0.4V_0.2 hydrogen storage sample manifests exceptional hydrogen kinetics (almost no incubation) and hydrogen storage capacity (1.73 wt%). The intrinsic reaction mechanism of Zr substitution is elucidated from the viewpoint of microstructure and strain engineering, combined with density functional theory (DFT) analysis. This study provides valuable insights into the design and application of high-performance TiMn₂ based multinary hydrogen storage alloys.