Hydrogen storage in Mg(2)Ni(Fe)H(4) nano particles synthesized from coarse-grained Mg and nano sized Ni(Fe) precursor

In this work, Mg(2)Ni(Fe)H(4) was synthesized using precursors of nano Ni(Fe) composite powder prepared through arc plasma method and coarse-grained Mg powder. The microstructure, composition, phase components and the hydrogen storage properties of the Mg–Ni(Fe) composite were carefully investigated. It is observed that the Mg(2)Ni(Fe)H(4) particles formed from the Mg–Ni(Fe) composite have a diameter of 100–240 nm and a portion of Fe in the Ni(Fe) nano particles transformed into α-Fe nano particles with the diameter of 40–120 nm. DSC measurements showed that the peak desorption temperature of the Mg(2)Ni(Fe)H(4) was reduced to 501 K and the apparent activation energy for hydrogen desorption of the Mg(2)Ni(Fe)H(4) was 97.2 kJ mol(−1) H(2). The formation enthalpy of Mg(2)Ni(Fe)H(4) was measured to be −53.1 kJ mol(−1) H(2). The improvements in hydrogen sorption kinetics and thermodynamics can be attributed to the catalytic effect from α-Fe nano particles and the destabilization of Mg(2)NiH(4) caused by the partial substitution of Ni by Fe, respectively.