Synergistic effect of rGO supported Ni3Fe on hydrogen storage performance of MgH2

Abstract

Bimetallic catalysts possess unique physical and chemical properties that distinct from the individual, which offer the opportunity to ameliorate the hydrogen storage properties of MgH2. Herein, a Ni3Fe catalyst homogeneously loaded on the surface of reduced graphene oxide (Ni3Fe/rGO) was prepared based on layered double hydroxide (LDH) precursor. The novel Ni3Fe/rGO nano-catalyst was subsequently doped into MgH2 to improve its hydrogen storage performance. The MgH2-5 wt.% Ni3Fe/rGO composite requires only 100 s to reach 6 wt% hydrogen capacity at 100 °C, while for MgH2 doped with 5 wt% Ni3Fe, Ni/rGO and Fe/rGO all require more than 500 s to uptake 3 wt% hydrogen under the same condition. The onset dehydrogenation temperature of the MgH2-5 wt.% Ni3Fe/rGO composite is about 185 °C, much lower than that of the MgH2 doped with 5 wt% Ni3Fe (205 °C), Ni/rGO (210 °C) and Fe/rGO (250 °C), and it can release H2 completely even in 1000 s at 275 °C. Besides, the MgH2-5 wt% Ni3Fe/rGO displays the lowest dehydrogenation apparent activation energy of 59.3 kJ/mol calculated by Kissinger equation. The synergetic effect attributing to rGO, in-situ formed active species of Mg2Ni and Fe is in charge of the excellent catalytic effect on hydrogen storage behavior of MgH2. Meanwhile, this study supplies innovative insights to design high efficiency catalysts based on the LDH precursor.