• The electronic structure and surface activity of Ni/CrV-MMO are optimized. • The onset desorption temperature of MgH 2 Ni/CrV-MMO is reduced to 190 °C. • The apparent activation energy of MgH 2 decreases by 47.5% compared with pristine MgH 2 . • The Ni/CrV-MMO + MgH 2 composite demonstrated a high hydrogen absorption capacity with 5.0 wt% in 10 min at 125 °C. • The synergistic effect between crystal Ni and amorphous CrV-MMO significantly enhances the hydrogen absorption/desorption kinetics of MgH 2 . Optimizing the kinetics and lowering the ab/dehydrogenation temperature of magnesium hydride (MgH 2 ) are crucial for hydrogen storage applications. The synergy among multi-metals (such as Ni, Cr, Fe, Cu, etc.) can reduce the ab/dehydrogenation activation energy of magnesium hydride by leveraging the characteristics of transition metals. Herein, Crystal-amorphous interfaces were regulated via changing the reducing atmosphere through precise design to form the semi-crystalline Ni/CrV-MMO catalysts. After the tests, the 10 wt%Ni/CrV-MMO-doped MgH 2 initial hydrogen release at 190 °C and desorbed 5.6 wt% H 2 at a relatively low temperature of 275 °C within 10 min. Moreover, this composite material absorbed 5.7 wt% H 2 within 2 min at 150 °C, achieving a remarkably low hydrogen absorption activation energy of only 28.35 kJ·mol −1 , which is far below pure MgH 2 (68.42 kJ·mol −1 ). Mechanistic studies and density functional theory (DFT) reveal that the amorphous CrV-MMO elevates the D-band center of Ni by contacting with the Ni interface, which weakens the Mg–H bond strength and consequently lowers the dehydrogenation barrier. The existence of crystal-amorphous interfaces effectively optimizes the transport of interfacial charges. This crystal-amorphous interface synergy strategy offers a general blueprint for low-temperature, high-rate MgH 2 storage systems.
Li et al. (Sun,) studied this question.