Graphene-Supported Sc 2 O 3 /TiO 2 for Superior Catalysis on Hydrogen Sorption Kinetics of MgH 2

Abstract

Complex metal oxide catalysts greatly accelerate the hydrogen sorption rates in the magnesium hydride system. In this study, the graphene-supported Sc 2 O 3 /TiO 2 catalyst is synthesized by means of a simple method, and a surprisingly synergetic effect of the Sc 2 O 3 -TiO 2 cocatalyst on the hydrogen storage performance of MgH 2 is observed. The MgH 2 -Sc 2 O 3 /TiO 2 @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 H 2 in 1 min and desorbs 5.71 wt% of H 2 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/MgH 2 -Sc 2 O 3 /TiO 2 @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.