Influence of metal oxide on LiBH4/2LiNH2/MgH2 system for hydrogen storage properties

In this study, various nanoscale metal oxide catalysts, such as CeO2, TiO2, Fe2O3, Co3O4, and SiO2, were added to the LiBH4/2LiNH2/MgH2 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 Fe2O3 > Co3O4 > CeO2 > TiO2 > SiO2. The onset dehydrogenation temperature was below 70 °C for the samples doped with Fe2O3 and Co3O4 with 10 wt.%. More than 5.4 wt.% hydrogen was released at 140 °C. X-ray diffraction indicated that the addition of metal oxides inhibited the formation of Mg(NH2)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 MgH2. The catalytic effect depends on the activation capability of oxygen species in metal oxides on hydrogen atoms in hydrides.

► Nanoscale metal oxides were added to LiBH4/2LiNH2/MgH2 system.
► The onset dehydrogenation temperature decreased remarkably.
► The interactions of metal oxides with MgH2 were detected.
► The order of the catalytic effect was Fe2O3 > Co3O4 > CeO2 > TiO2 > SiO2.
► Catalytic effect depends on the activation capability of O on H in hydrides.