Research Regarding Molybdenum Flakes’ Improvement on the Hydrogen Storage Efficiency of MgH2

Abstract

As an efficient hydrogen storage material, magnesium hydride (MgH2) has a high capacity of 7.6 wt%. However, its performance deteriorates because of high thermodynamic and kinetic temperatures and the fast agglomeration of its nanocrystals during the hydrogen uptake and release process. The exploration of efficient catalysts is a popular, but currently challenging, topic. Therefore, we successfully prepared flake-like molybdenum (Mo) catalysts and doped them into MgH2 to enhance its properties. We found that the incorporation of 7wt%Mo into MgH2 could reduce the starting desorption temperature by approximately 100 °C. In addition, the 7wt%Mo-doped MgH2 could desorb almost all of the H2 within 20 min at a 325 °C isothermal condition. For hydrogenation, MgH2-7wt%Mo could absorb approximately 5 wt% of hydrogen within 5 min at a 250 °C isothermal condition with a hydrogen pressure of 3 MPa. In addition, the MgH2-7wt%Mo composite could maintain approximately 98% of the initial capacity at the end of 22 cycles, presenting good cycling performance.