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

Abstract

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.