Graphene-Supported Sc2O3/TiO2 for Superior Catalysis on Hydrogen Sorption Kinetics of MgH2

Complex metal oxide catalysts greatly accelerate the hydrogen sorption rates in the magnesium hydride system. In this study, the graphene-supported Sc2O3/TiO2 catalyst is synthesized by means of a simple method, and a surprisingly synergetic effect of the Sc2O3-TiO2 cocatalyst on the hydrogen storage performance of MgH2 is observed. The MgH2-Sc2O3/TiO2@Gn composite starts to release hydrogen at 140 °C and reaches the peak dehydrogenation temperature at 239.9 °C. It absorbs 6.55 wt% of H2 in 1 min and desorbs 5.71 wt% of H2 in 10 min at 300 °C, showing excellent hydrogen absorption and desorption performance. Furthermore, with the decrease of the grain size and changes in the structure, the activity of the catalyst is greatly improved. The low-valent titanium and scandium and oxygen vacancies formed in the process of dehydrogenation facilitate hydrogen diffusion and electron transfer, and further improve the kinetic performance of the Mg/MgH2-Sc2O3/TiO2@Gn system. This study aims to provide insights into studying complex metal oxides as catalysts to improve hydrogen storage performance, and shed light on other catalysis-related research.