NiFe2O4 nanoparticles catalytic effects of improving LiAlH4 dehydrogenation properties

Abstract

The effects of NiFe2O4 nanoparticles addition on the dehydrogenation behavior of LiAlH4 were investigated. The onset dehydrogenation temperature for LiAlH4+3 mol % NiFe2O4 sample is 61 degrees C, which decreased by 94 degrees C compared with the as-received LiAlH4 and released similar to 7.2 wt % hydrogen when heated to 180 degrees C. Isothermal desorption measurements show that the 3 mol % NiFe2O4-doped sample releases similar to 7.0 wt % of hydrogen in 91 min at 120 degrees C, which is 6.3 wt % higher than the as-received LiAlH4 under the same conditions. Through calculating the apparent activation energy of the LiAlH4 samples with and without NiFe2O4 for the first two dehydrogenation stages, the E-a of the LiAlH4+3 mol % NiFe2O4 sample is 54.3 and 70.8 kJ/mol, resulting in 52.5 and 59% decrease, respectively, compared with the as-received LiAlH4. Analyzing the X-ray diffraction and Fourier transform infrared spectroscopy results, it is reasonable to believe that the remarkable improvement of dehydrogenation properties of NiFe2O4-doped LiAlH4 results from the in situ formed LiFeO2 and Al-Ni compounds, providing the active sites for nucleation and growth of the dehydrogenation products.