Influence of metal oxide on LiBH4/2LiNH_2/MgH_2 system for hydrogen storage properties

摘要

In this study, various nanoscale metal oxide catalysts, such as CeC>2, TiO_2, Fe_2O_3, Co_3O_4, and SiO_2, were added to the LiBH4/2LiNH_2/MgH_2 system by using high-energy ball milling. Temperature programmed desorption and MS results showed that the Li-Mg-B-N-H/ oxide mixtures were able to dehydrogenate at much lower temperatures. The order of the catalytic effect of the studied oxides was Fe_2O_3 > Co_3O_4 > CeO_2 > TiO_2 > SiO_2. The onset dehydrogenation temperature was below 70 ℃ for the samples doped with Fe_2O_3 and Co_3O_4 with 10 wt.%. More than 5.4 wt.% hydrogen was released at 140 ℃. X-ray diffraction indicated that the addition of metal oxides inhibited the formation of Mg(NH_2)_2 during ball milling processes. It is thought that the changing of the ball milling products results from the interaction of oxide ions in metal oxide catalysts with hydrogen atoms in MgH_2. The catalytic effect depends on the activation capability of oxygen species in metal oxides on hydrogen atoms in hydrides.