Available online 12 January 2023
Abstract
As a promising hydrogen storage material,
the practical application of magnesium is obstructed by the stable
thermodynamics and sluggish kinetics. In this paper, three kinds of
NiTiO3 catalysts with different mole ratio of Ni to Ti
were successfully synthesized and doped into nanocrystalline Mg to
improve its hydrogen storage properties. Experimental results indicated
that all the Mg-NiTiO3 composites showed prominent hydrogen storage performance. Especially, the Mg-NiTiO3/TiO2 composite could take up hydrogen at room temperature and the apparent
activation energy for hydrogen absorption was dramatically decreased
from 69.8 ± 1.2 (nanocrystalline Mg) kJ/mol to 34.2 ± 0.2 kJ/mol. In
addition, the hydrogenated sample began to release hydrogen at about
193.2 °C and eventually desorbed 6.6 wt% H2. The desorption enthalpy of the hydrogenated Mg-NiTiO3-C
was estimated to be 78.6 ± 0.8 kJ/mol, 5.3 kJ/mol lower compared to
83.9 ± 0.7 kJ/mol of nanocrystalline Mg. Besides, the sample revealed
splendid cyclic stability during 20 cycles. No obvious recession
occurred in the absorption and desorption kinetics and only 0.3 wt%
hydrogen capacity degradation was observed. Further structural analysis
demonstrates that nanosizing and catalyst doping led to a synergistic
effect on the enhanced hydrogen storage performance of Mg-NiTiO3-C composite, which might serve as a reference for future design of highly effective hydrogen storage materials.
Keywords