MgH2@Mg(BH4)2 Core–Shell-like Nanostructures: Synthesis, Hydrolysis Performance, and Promotion Mechanism

The hydrolysis of hydrides, represented by MgH₂, delivers substantial capacity and presents an appealing prospect for an on-site hydrogen supply. However, the sluggish hydrolysis kinetics and low hydrogen yield of MgH₂ caused by the formation of a passivation Mg(OH)₂ layer hinder its practical application. Herein, we present a dual strategy encompassing microstructural design and compounding, leading to the successful synthesis of a core-shell-like nanostructured MgH₂@Mg(BH₄)₂ composite, which demonstrates excellent hydrolysis performance. Specifically, the optimal composite with a low E_a of 9.05 kJ mol^-1 releases 2027.7 mL g^-1 H₂ in 60 min, and its hydrolysis rate escalates to 1356.7 mL g^-1 min^-1 H₂ during the first minute at room temperature. The nanocoating Mg(BH₄)₂ plays a key role in enhancing the hydrolysis kinetics through the release of heat and the formation of local concentration of Mg²⁺ field after its hydrolysis. This work offers an innovative concept for the design of hydrolysis materials.