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 MgH bonds, and thus improved the reversible hydrogen storage performance of MgH2.