Synthesis, Crystal Structure, and Hydrogen Storage Properties of an AB₃-Based Alloy Synthesized by Disproportionation Reactions of AB₂-Based Alloys

Hydrogen storage materials store hydrogen in their atomic states, enabling more compact and safer storage methods compared to those for gaseous and liquid hydrogen. Although various types of hydrogen storage materials have been reported, new materials with higher hydrogen storage capacities and enhanced durability are required. Herein, we report the synthesis, crystal structure, and hydrogen storage properties of an AB₃-based alloy, Y_0.68Mg_0.32Co_3.00, which exhibited reversible hydrogen absorption and desorption with a hydrogen storage capacity of 1.68 mass % and minimal degradation over 100 cycles at 303 K. The hydrogen storage capacity of Y_0.68Mg_0.32Co_3.00 exceeds that of LaNi₅, a reported hydrogen storage material with 1.38 mass %. It further increased to 2.88 mass % at room temperature under 10 GPa. This finding suggests that Y_0.68Mg_0.32Co_3.00 has the potential for even greater hydrogen storage capacity. This could lead to more compact and lightweight storage solutions for hydrogen energy devices.