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

Abstract

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.