in-situ formed Pt nano-clusters serving as destabilization-catalysis bi-functional additive for MgH₂

MgH₂ as one of potential solid-state hydrogen storage materials has been widely investigated during past decades due to its large capacity and abundant elemental reserves. Nonetheless, the presented ultra-high thermal stability and sluggish kinetics hinder a further application. In the present work, the Ni and Pt nano-clusters evolved from Ni@Pt core–shell nanoparticles facilitated the de/re-hydrogenation process of MgH₂. The onset dehydrogenation temperature of MgH₂-10 wt% Ni@Pt was greatly lowered by maximum 108 K compared with 601 K of the pristine MgH₂, and the dehydrogenation process can be terminated below 573 K. The thermal stability of the MgH₂-based system was remarkably tailored to 69.4 kJ (mol H₂)^-1 from 76.2 kJ (mol H₂)^-1 of the pristine MgH₂. Meanwhile, the hydrogen storage kinetics of MgH₂-10 wt% Ni@Pt was greatly improved compared with the pristine MgH₂. Density functional theory calculations confirmed that Pt nano-clusters serving as a destabilizer and catalyst not only greatly destabilize the thermal stability of MgH₂ but also catalyze its reactions, in particular with the Pt(2 2 0) slab. The effective catalyst-reactant interfaces coupling with regulated surface determined desorption/absorption were deeply investigated and built, leading to an excellent agreement with experiments. The involving of transition metal clusters lays foundation of a new way of improving the hydrogen storage properties and paves a way of developing next-generation hydrogen storage materials.