Remarkable catalysis of spinel ferrite XFe2O4 (X = Ni, Co, Mn, Cu, Zn) nanoparticles on the dehydrogenation properties of LiAlH4: an experimental and theoretical study

Abstract Safe, compact, lightweight and cost-effective hydrogen storage is one of the main challenges that need to be addressed to effectively deploy the hydrogen economy. LiAlH4, as a solid-state hydrogen storage material, presents several advantages such as high hydrogen storage capacity, low price and abundant sources. Unfortunately, neither thermodynamic nor kinetic properties of dehydrogenation for LiAlH4 can fulfill the requirements of practical application. Thus, a series of spinel ferrite nanoparticles such as XFe2O4 (X = Ni, Co, Mn, Cu, Zn, Fe) were prepared by using the modified thermal decomposition method, and then doped into LiAlH4 by using ball milling. Our results show that LiAlH4 doped with 7 wt% NiFe2O4 starts to release hydrogen at 69.1°C, and the total amount of hydrogen released is 7.29 wt% before 300°C. The activation energies of the two-step hydrogen release reactions of LiAlH4 doped with 7 wt% NiFe2O4 are 42.32 kJ mol−1 and 71.42 kJ mol−1, which are 59.0% and 63.6% lower than those of as-received LiAlH4, respectively. Combining the density functional theory calculations, we reveal that both the presence of NiFe2O4 and in-situ formed Al4Ni3 in ball-milling decrease the desorption energy barrier of Al-H bonding in LiAlH4 and accelerate the breakdown of Al-H bonding through the interfacial charge transfer and the dehybridization of the Al-H cluster. Thus, the experimental and theoretical results open a new avenue toward designing high effective catalysts applied to LiAlH4 as a candidate for hydrogen storage.