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The addition of a catalyst and ball milling process was found to be one of the efficient method to reduce the decomposition temperature and improve the desorption kinetics of lithium aluminium hydride (LiAlH 4). In this paper, a transition metal oxide, LaFeO 3 was used as a catalyst. Decomposition temperature of the 10 wt% of LaFeO 3 -doped LiAlH 4 system was found to be lowered from 143 °C to 103 °C (first step) and from 175 °C to 153 °C (second step), respectively. In isothermal desorption kinetics, the amount of hydrogen released of the doped sample was improved to 3.9 wt% in 2.5 h at 90 °C. Meanwhile, the undoped sample had released less than 1.0 wt% of hydrogen under the same condition. The activation energy of the LaFeO 3 -doped LiAlH 4 sample was measured to be 73 kJ/mol and 90 kJ/mol for the first two dehydrogenation reactions compared to 107 kJ/mol and 119 kJ/mol for the undoped sample. The improvements of desorption properties were the results from the formation of LiFeO 2 , Fe and La or La-containing phase during the heating process. • The H 2 storage properties of LiAlH 4 /LaFeO 3 have been studied for the first time. • Dehydrogenation properties of LiAlH 4 are improved after adding with LaFeO 3. • The LiAlH 4 /LaFeO 3 composite releases 3.9 wt% in 2.5 h at 90 °C. • The formation of LiFeO 2 , Fe and La or La-containing phase plays a catalytic role. [ABSTRACT FROM AUTHOR]

Abstract In this study, the hydrogenation performance of NaBH 4 was modified by the addition of 10 wt% MgFe 2 O 4 as the catalyst. The NaBH 4 + 10 wt% of MgFe 2 O 4 sample was prepared by a ball milling technique. The onset decomposition temperature of MgFe 2 O 4 -doped NaBH 4 was decreased to 323 °C and 483 °C for the first and second stage of dehydrogenation as compared to the milled NaBH 4 (497 °C). The desorption kinetics study showed that the addition of MgFe 2 O 4 caused the sample to had faster hydrogen desorption with a capacity of 6.2 wt% within 60 min while the milled NaBH 4 had only released 5.3 wt% of hydrogen in the same period of time. For the isothermal absorption kinetics, the total amount of hydrogen absorbed by the milled NaBH 4 was 3.7 wt% while the NaBH 4 + 10 wt% MgFe 2 O 4 sample showed better absorption characteristic with a total amount of 4.5 wt% of hydrogen within 60 min. The calculated desorption activation energy from the Kissinger plot of NaBH 4 + 10 wt% MgFe 2 O 4 sample was 187 kJ/mol which reduced by 28 kJ/mol than the milled NaBH 4 (215 kJ/mol). The in-situ formation of MgB 6 and Fe 3 O 4 after the dehydrogenation process indicates that these new species were responsible for the improved hydrogenation performances of NaBH 4. Highlights • The hydrogenation performance of NaBH 4 was modified by MgFe 2 O 4. • MgFe 2 O 4 showed superior catalytic effects for NaBH 4. • Doped sample could desorb 6.2 wt% H 2 within 60 min at 420 °C. • MgFe 2 O 4 -doped NaBH 4 could absorb 4.5 wt% H 2 within 60 min at 420 °C. • The new species of MgB 6 and Fe 3 O 4 play a synergistic role. [ABSTRACT FROM AUTHOR]

A sample of Fe 2 O 3 -doped 4MgH 2 -Li 3 AlH 6 composite was prepared by the ball milling technique, and the hydrogen storage properties were investigated for the first time. Results showed that the addition of Fe 2 O 3 powder reduced the decomposition temperature and improved de/hydrogenation kinetics compared with undoped 4MgH 2 -Li 3 AlH 6 . The onset decomposition temperature for the Fe 2 O 3 -doped 4MgH 2 -Li 3 AlH 6 composite decreased by 75 °C compared with that of the undoped composite. For the sorption kinetics, a hydrogen absorption capacity of 2.4 wt% was reached after 60 min in the 10 wt% Fe 2 O 3 -doped 4MgH 2 -Li 3 AlH 6 composite, whereas the neat composite absorbed 2.3 wt% hydrogen under the same conditions. For desorption kinetics, the Fe 2 O 3 -doped 4MgH 2 -Li 3 AlH 6 sample released 2.5 wt% hydrogen under 10 min of dehydrogenation, but the neat 4MgH 2 -Li 3 AlH 6 composite only desorbed 2.0 wt% hydrogen within the same period. The apparent activation energy calculated by Kissinger analysis for hydrogen desorption decreased to 112.9 kJ/mol after Fe 2 O 3 was added compared with the undoped composite, which was 145.4 kJ/mol. The X-ray diffraction analysis shows the formation new phase of Li 2 Fe 3 O 4 in the doped sample after ball milling processes that could act as the real catalyst in the Fe 2 O 3 -doped 4MgH 2 -Li 3 AlH 6 composite. [ABSTRACT FROM AUTHOR]

Study on the catalytic roles of MgFe 2 O 4 on the dehydrogenation performance of LiAlH 4 was carried out for the first time. Notable improvement on the dehydrogenation of LiAlH 4 –MgFe 2 O 4 compound was observed. The initial decomposition temperatures for the catalyzed LiAlH 4 were decreased to 95 °C and 145 °C for the first and second stage reactions, which were 48 °C and 28 °C lower than the milled LiAlH 4. As for the desorption kinetics performance, the MgFe 2 O 4 doped-LiAlH 4 sample was able to desorb faster with a value of 3.5 wt% of hydrogen in 30 min (90 °C) while the undoped LiAlH 4 was only able to desorb 0.1 wt% of hydrogen. The activation energy determined from the Kissinger analysis for the first two desorption reactions were 73 kJ/mol and 97 kJ/mol; which were 31 and 17 kJ/mol lower as compared to the milled LiAlH 4. The X-ray diffraction result suggested that the MgFe 2 O 4 had promoted significant improvements by reducing the LiAlH 4 decomposition temperature and faster desorption kinetics through the formation of active species of Fe, LiFeO 2 and MgO that were formed during the heating process. • The H 2 storage properties of LiAlH 4 /MgFe 2 O 4 have been studied for the first time. • Desorption properties of LiAlH 4 are improved after adding with MgFe 2 O 4. • LiAlH 4 //MgFe 2 O 4 composite could desorb 3.5 wt% H 2 within 30 min at 90 °C. • The formation of new species of Fe, LiFeO 2 and MgO phases plays a catalytic role. [ABSTRACT FROM AUTHOR]

Abstract The influence of CuFe 2 O 4 addition on the sorption performances of MgH 2 prepared by ball milling was studied for the first time. The MgH 2 + 10 wt% CuFe 2 O 4 sample exhibited an enhancement in hydrogen storage performance compared to that of as-milled MgH 2 , with the onset decomposition temperature decreased from 340 °C to 250 °C. Dehydrogenation kinetic result revealed that CuFe 2 O 4 -added MgH 2 released around 5.3 wt% H 2 within 10 min at 320 °C, while the as-milled MgH 2 released below 1.0 wt% H 2 under the same condition. Furthermore, about 5.0 wt% H 2 was absorbed at 250 °C in 30 min for the 10 wt% CuFe 2 O 4 -doped MgH 2 sample. In contrast, the un-doped MgH 2 only absorbed 4.0 wt% H 2 at 250 °C in 30 min. From the Kissinger analysis, the apparent activation energy of as-milled MgH 2 was 166.0 kJ/mol and this value decreased to 113.0 kJ/mol for 10 wt% CuFe 2 O 4 -added MgH 2. The enhanced sorption performance of MgH 2 in the presence of CuFe 2 O 4 is believed to be due to the role of in situ formed Fe, Mg-Cu alloy, and MgO phases as an active species to catalyse the hydrogen storage properties of MgH 2. Highlights • The hydrogen storage properties of CuFe 2 O 4 -doped MgH 2 have been investigated. • The addition of CuFe 2 O 4 improves the hydrogen storage properties of MgH 2. • The in-situ formation of Fe, Mg-Cu alloy, and MgO may play a synergetic catalytic role. [ABSTRACT FROM AUTHOR]