Transition metal-engineered magnesium-based materials for advanced hydrogen storage: From multifaceted mechanisms to state-of-the-art systems

Magnesium-based materials show great promise for solid-state hydrogen storage, yet their practical implementation is hindered by sluggish kinetics and high thermodynamic stability. This review critically analyzes recent advancements in transition metal modification of Mg-based systems, elucidating the multifaceted roles of these additives in catalysis, alloying, and nanostructuring. We examine cutting-edge research on Ti-, V-, Ni-, Nb-, Pd-, La-, and Ce-modified materials, providing insights into the complex interplay between transition metals and the Mg matrix. Advanced characterization techniques and computational studies reveal atomic-scale mechanisms underlying improved thermodynamics, kinetics, and cycling stability. While highlighting significant progress, we identify persistent challenges including the kinetics-capacity trade-off and long-term stability issues. The review proposes innovative strategies such as advanced nanoarchitectural design, defect engineering, and machine learning-assisted materials discovery. By synthesizing current knowledge and future directions, this work aims to guide the rational design of optimized Mg-based hydrogen storage systems for clean energy applications.