MgH2 contains a high content of 7.6 wt % H2. However,
its poor kinetics and high thermodynamic stability exhibit
unacceptably low energy efficiency. Catalyst doping is deemed as one
of the most effective strategies to improve its kinetic performance.
In this work, porous rod-like TMTiO3 (TM = Ni and Co) samples
are designed and introduced into an MgH2 system for the
first time. TMTiO3 exhibits a high catalytic effect on
the hydrogen desorption performance of MgH2. In particular,
MgH2–6% NiTiO3 possesses excellent catalytic
efficiency with a relatively low dehydrogenation temperature (235
°C) and fast dehydrogenation rate (∼0.1842 wt %/min at
235 °C), and the sample exhibits wonderful cycling stability
with respect to both capacity (6.4 wt %) and kinetics (∼0.64
wt %/min at 300 °C). Mechanistic research shows that the in situ-formed
Mg2Ni/Mg2NiH4 phases are regarded
as catalytically active species, which work as a “Hydrogen
Pump” and make the hydrogen release easier. Meanwhile, the
interconversion within multivalent titanium (Ti4+, Ti3+, and Ti2+) that acts as a carrier for electron
transformation leads to easy H formation from H–. The synergetic catalytic effects between Mg2Ni/Mg2NiH4 and multivalent titanium result in favorable
and lasting catalytic efficiency for the enhanced hydrogen desorption
properties of the MgH2 system.