Constructing a Favorable Microenvironment for Robust Hydrogen Storage in MgH ₂ Through Synergistic Cooperation With Mn and Mg ₂ Ni

ABSTRACT Weakening the electrostatic attraction between Mg 2+ ions and H − ions in MgH 2 is vital for improving the kinetic performance of MgH 2 for hydrogen storage. Herein, a multivalent microenvironment is synergistically created by Mn and Mg 2 Ni to break the stable structure of MgH 2 , enabling rapid and stable de/hydrogenation performance. Specifically, the catalyzed MgH 2 system rapidly emits 5.98 wt% H 2 at 265°C within just 20 min and swiftly absorbs 6.24 wt% H 2 at 150°C in a mere 10 min. Microscopic characterization shows that a tight interface is formed between Ni and Mn 2 O 3 , which provides a stable anchor point for the formation of hydrogen pumps. Additionally, the multivalency of Mn and abundant oxygen vacancies accelerate the electron transfer and provide the shortest path for H dissociation. Moreover, density functional theory (DFT) indicates that Mg‐H is extracted from 0.173 to 0.204 nm after modification, achieving a reduced decomposition energy of MgH 2 . Besides, 97.8% reversible hydrogen storage capacity was maintained after 30 cycles, presenting prominent potential for practical applications.