Thermodynamic and kinetic destabilization of Mg solid-solution alloys with nanosized grains for hydrogen storage

• (Mg0.9In0.1)0.25Mn0.75 nanocomposite with ~61 nm Mg(In) nanograins exhibits superior hydrogen storage performance. • Dehydrogenation is significantly facilitated: onset and peak temperatures drop to ~120°C and ~240°C, respectively, compared with pure MgH2. • A low activation energy of ~78.34 kJ/mol demonstrates markedly enhanced kinetics, while cycling stability reaches 97% retention after 50 cycles. • The synergistic combination of solid-solution formation and nanoscale engineering effectively destabilizes the Mg–H bonds both thermodynamically and kinetically.