Effects of nano-confinement on the hydrogen desorption properties of MgH2

► MgH2/C composite was synthesized inside the mesopores of CMK3 and SBA15 templates. ► Hydrogen desorption temperatures of MgH2/CMK3 were influenced by the MgH2 loading. ► MgH2/CMK3 with 20 wt% loading released hydrogen at a temperature as low as 253 °C. ► TEM image of MgH2/CMK3 revealed MgH2 nanocrystallites (d∼4 nm) inside pores of CMK3. ► Decomposition enthalpy of 52.38±2.16 kJ/mol H2 was obtained from van't Hoff plot.