Influence of Nanosized CoTiO3 Synthesized via a Solid-State Method on the Hydrogen Storage Behavior of MgH2

Abstract

Magnesium hydride (MgH2) has received outstanding attention as a safe and efficient material to store hydrogen because of its 7.6 wt.% hydrogen content and excellent reversibility. Nevertheless, the application of MgH2 is obstructed by its unfavorable thermodynamic stability and sluggish sorption kinetic. To overcome these drawbacks, ball milling MgH2 is vital in reducing the particle size that contribute to the reduction of the decomposition temperature. However, the milling process would become inefficient in reducing particle sizes when equilibrium between cold-welding and fracturing is achieved. Therefore, to further ameliorate the performance of MgH2, nanosized cobalt titanate (CoTiO3) has been synthesized using a solid-state method and was introduced to the MgH2 system. The different weight percentages of CoTiO3 were doped to the MgH2 system, and their catalytic function on the performance of MgH2 was scrutinized in this study. The MgH2 + 10 wt.% CoTiO3 composite presents the most outstanding performance, where the initial decomposition temperature of MgH2 can be downshifted to 275 °C. Moreover, the MgH2 + 10 wt.% CoTiO3 absorbed 6.4 wt.% H2 at low temperature (200 °C) in only 10 min and rapidly releases 2.3 wt.% H2 in the first 10 min, demonstrating a 23-times-faster desorption rate than as-milled MgH2 at 300 °C. The desorption activation energy of the 10 wt.% CoTiO3-doped MgH2 sample was dramatically lowered by 30.4 kJ/mol compared to undoped MgH2. The enhanced performance of the MgH2–CoTiO3 system is believed to be due to the in situ formation of MgTiO3, CoMg2, CoTi2, and MgO during the heating process, which offer a notable impact on the behavior of MgH2.

Ni0.6Zn0.4O Synthesised via a Solid-State Method for Promoting Hydrogen Sorption from MgH2

“…This revealed that the addition of Ni 0.6 Zn 0.4 O as an additive to MgH 2 resulted in a notable decrease in the kinetic barrier desorption of the MgH 2 system, which is beneficial for hydrogen release from MgH 2 . These findings are also consistent with earlier research that showed the addition of an additive or catalyst lowers the activation energy of MgH 2 [ 56 , 57 ]. Zhang and co-workers [ 58 ] exposed that the reaction energy barrier for the desorption reduced to 109 kJ/mol when MnMoO 4 was doped to MgH 2 .…”

“…As expected, MgH 2 –10 wt.% Ni 0.6 Zn 0.4 O samples exhibited a smaller particle size as compared with milled MgH 2 (as can be seen in Figure 7 c). Ali et al [ 56 ] introduced CoTiO 3 to MgH 2 and showed that the particle size of the composite changed to a finer and smaller size. According to the research results of Somo et al [ 63 ], smaller particle sizes allow quick dissociation into the surface of materials.…”

Improved Dehydrogenation Properties of LiAlH4 by Addition of Nanosized CoTiO3

“…Without any prior processing, LiAlH 4 (95% pure) from Sigma Aldrich was used. The nanosized CoTiO 3 was synthesised via the solid-state method, as explained in our previous work [ 33 ]. Then, various amounts of CoTiO 3 (5 wt.%, 10 wt.%, 15 wt.% and 20 wt.%) were doped with LiAlH 4 to study its influence on the desorption behaviour of LiAlH 4 .…”

Transition metal-based materials and their catalytic influence on MgH2 hydrogen storage: A review

“…Carbon also provided a confinement effect which also aided the stability of MgH2 during de/hydrogenation cycles. Ali et al (2022) doped MgH2 with 10 wt.% CoTiO3. Hydrogen was desorbed at 270 o C, which was lower than that of MgH2 that occurred at 340 o C. Within the first 10 min, 6.4 wt.% H2 was adsorbed.…”