Facile and low-cost synthesis of carbon-supported manganese monoxide nanocomposites and evaluation of their superior catalytic effect toward magnesium hydride

Abstract A carbon-supported manganese monoxide nanocomposite (MnO@C) was synthesized using a low-cost D113 cation exchange resin and manganese acetate tetrahydrate to improve the dehydrogenation/hydrogenation properties of magnesium hydride (MgH2). It was found that the dehydrogenated MnO@C-doped MgH2 composite could uptake 6.0 wt% of hydrogen within 60 min at 100 °C, and it could even uptake hydrogen at ambient temperature. Moreover, the synthesized composite could release approximately 5.0 wt% of hydrogen within 6 min at 300 °C. The dehydrogenation and hydrogenation apparent activation energies of MnO@C-doped MgH2 were calculated as 94.6 kJ mol−1 and 22.5 kJ mol−1, respectively, which were reduced by 38.8% and 67.2% when compared to the undoped sample. The density functional theory revealed that Mn and Mg0.9Mn0.1O facilitated the fracture of Mg H bonds, and thus improved the reversible hydrogen storage performance of MgH2.