Hydrogen storage properties of MgH2 modified by efficient Co3V2O8 catalyst

Developing medium temperature hydrogen storage materials is important for the practical application of the Studies have demonstrated that V-based catalysts exhibit exceptional catalytic activity in the dehydrogenation of MgH2 at medium levels. However, the V-base catalysts primarily concentrates on hydrogen desorption, and there is a necessity for further enhancement of hydrogen absorption properties. To solve this problem, herein we prepared a bimetallic oxide. Co can enhance the hydrogen absorption and desorption properties of MgH2 as the catalyst and it influences the performance of hydrogen absorption more obviously than the hydrogen desorption performance. It is found that MgH2 catalyzed by Co3V2O8 can absorb 1.31 wt% hydrogen within 30 min even under room temperature and can release 3.41 wt% hydrogen within 120 min at temperatures as low as 225 °C. The activation energy of MgH2-6 wt.%Co3V2O8 is determined to 68.5 kJ/mol, which is 50.2 % lower than that of Ball-MgH2. XRD combined with TEM measurements revealed that the in-situ formed Co and V2O3 can weaken the HH and MgH bonds respectively to improve the hydrogen storage properties of MgH2. These discoveries provide guideline of the further design of high efficiency catalysts for Mg-based hydrogen storage materials.