Achieving both high hydrogen capacity and low decomposition temperature of the metastable AlH3 by proper ball milling with TiB2

AlH₃ is a metastable hydride with a high hydrogen density of 10.1 wt% and it can release hydrogen at a low temperature of 150–200 °C. Many additives (e.g., NbF₅, TiF₃, etc.) introduced by ball milling can significantly reduce the decomposition temperature of AlH₃, but often simultaneously decrease the available hydrogen capacity. In this work, TiB₂ was introduced by ball milling to improve the decomposition performance of AlH₃. AlH₃ + x wt% TiB₂ (x = 2.5, 5, 7.5, 10) composites were prepared by ball milling, and the milling conditions were optimized. It was shown that the decomposition performance of the AlH₃ + 2.5 wt% TiB₂ ball milled at 225 rpm for 108 min is the best. The onset decomposition temperature is 78 °C, which is 60 °C lower than that of pure AlH₃. The decomposition is terminated at 130 °C with 8.5 wt% of hydrogen is obtained. In addition, 5.3 wt% of hydrogen can be released within 200 min at constantly 80 °C. Under the same conditions, ball-milled AlH₃ can hardly release any hydrogen. The activation energy calculated by the Kissinger's method is 86 kJ mol^?1, which was 28 kJ mol^?1 lower than that of ball-milled AlH₃. Catalytic mechanism study reveals that the Al₂O₃ layers on the surface of AlH₃ will interact with TiB₂ to form Al–Ti–B solid solution, resulting in lattice distortion. Through lattice activation, the decomposition kinetics of AlH₃ is improved. This work provides an efficient strategy to achieve both high hydrogen capacity and low decomposition temperature of metastable AlH₃ by proper ball milling with metal borides.     

Modifying the hydrogen storage performances of NaBH4 by catalyzing with MgFe2O4 synthesized via hydrothermal method

In this study, the hydrogenation performance of NaBH₄ was modified by the addition of 10 wt% MgFe₂O₄ as the catalyst. The NaBH₄ + 10 wt% of MgFe₂O₄ sample was prepared by a ball milling technique. The onset decomposition temperature of MgFe₂O₄-doped NaBH₄ was decreased to 323 °C and 483 °C for the first and second stage of dehydrogenation as compared to the milled NaBH₄ (497 °C). The desorption kinetics study showed that the addition of MgFe₂O₄ caused the sample to had faster hydrogen desorption with a capacity of 6.2 wt% within 60 min while the milled NaBH₄ 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 NaBH₄ was 3.7 wt% while the NaBH₄ + 10 wt% MgFe₂O₄ 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 NaBH₄ + 10 wt% MgFe₂O₄ sample was 187 kJ/mol which reduced by 28 kJ/mol than the milled NaBH₄ (215 kJ/mol). The in-situ formation of MgB₆ and Fe₃O₄ after the dehydrogenation process indicates that these new species were responsible for the improved hydrogenation performances of NaBH₄.     

Reinforce the dehydrogenation process of LiAlH4 by accumulating porous activated carbon

Herein, it is reported that activated carbon (AC) alters the hydrogen storage behavior of lithium alanate (LiAlH₄) prepared by the ball milling technique. Notable improvements in onset decomposition temperature and desorption kinetics are attained for LiAlH₄ added 10 wt.% of AC composite compared to as-received and as-milled LiAlH₄. The onset decomposition temperature of LiAlH₄-10 wt.% AC dropped to 100 °C and 160 °C for the first and second steps. The composite also released 3.4 wt.% of hydrogen after 90 min compared to as-received and as-milled which is less than 0.2 wt.% of hydrogen within the same period. The XRD result discovered an additional peak of the Li₃AlH₆ and Al compounds appeared after the milling process, concluding that LiAlH₄ becomes unstable after the addition of AC. FTIR measurement has verified the presence of the Li₃AlH₆ and carbon bonding in the LiAlH₄-10 wt.% AC composite. The composite's activation energy (E_a) for the first and second steps is 70 kJ/mol and 85 kJ/mol, respectively. These values decrease from as-milled LiAlH₄ for both steps, demonstrating the catalytic effect of AC in this system. FESEM images illustrate that after ball milling, the particle size of LiAlH₄-10 wt.% AC composite decreases. The considerable improvement in the hydrogen storage characteristic of the LiAlH₄-10 wt.% AC composite is thought to be the collaborative role of amorphous carbon.     

A study on the hydrogen storage properties and reaction mechanism of Na3AlH6LiBH4 composite system

In this work, the hydrogen storage properties of different molar ratio (in mole of 1:3 and 1:4) Na₃AlH₆LiBH₄ system is investigated for the first time. X-ray diffraction and Fourier transform infrared results show that the Na₃AlH₆LiBH₄ with molar ratio of 1:3 and 1:4 composite was transformed to Li₃AlH₆ and NaBH₄ phases via a metathesis reaction during a ball-milling process for 6 h. Temperature-programmed-desorption (TPD) results show three stages of decomposition for the Na₃AlH₆LiBH₄ (in mole ratio of 1:3 and 1:4) composite resulting from Li₃AlH₆ and NaBH₄ phases. From the TPD graph, the Na₃AlH₆LiBH₄ composite with molar ratio of 1:4 had showed better performance of hydrogenation properties compared to with molar ratio of 1:3. The composite began to release hydrogen at 180 °C in relation to decomposition of the Li₃AlH₆ stage into LiH and Al. The NaBH₄ stage then began to decompose at approximately 380 °C, after reacting with Al to form an intermetallic phase, AlB₂, which occurred at 100 °C lower than as-milled NaBH₄. At 430 °C, the un-reacted NaBH₄ was decomposed after catalysing with AlB₂. Kissinger analysis shows the apparent activation energy of NaBH₄ decomposition in the hydrides composite was reduced by about 75 kJ/mol compared to the as-milled NaBH₄. The rehydrogenation process evidenced the reversibility of NaBH₄. Based on these results, the intermetallic phase, AlB₂, is considered to have played an important role by lowering the operating temperature and providing access to the full hydrogen content in the Na₃AlH₆LiBH₄ composite system.     

Significant effect of TiF3 on the performance of 2NaAlH4+Ca(BH4)2 hydrogen storage properties

Titanium fluoride (TiF₃) is doped into the reactive hydride composite of 2NaAlH₄ + Ca(BH₄)₂ by ball milling to enhance the hydrogen storage properties of the composite system. NaAlH₄ and Ca(BH₄)₂ phases were fully transformed to Ca(AlH₄)₂ and NaBH₄ phases after the ball-milling process (6 h). Four major stages were discovered in the undoped and TiF₃-doped system, which is corresponding to; (i) Ca(AlH₄)₂, (ii) CaAlH₅, (iii) CaH₂ and (iv) NaBH₄, respectively. The addition of TiF₃ to the studied composite resulted in both reduced decomposition temperature and enhanced sorption kinetics compared with the undoped composite. The onset desorption temperature was reduced from 125 °C to 60 °C for the first stage in the TiF₃-doped composite, compared with the undoped composite. From differential scanning calorimetry analysis, the decomposition temperature for all stages has shifted to a lower temperature after doping with TiF₃. The activation energy has greatly reduced by 63.6 and 21.9 kJ/mol for CaAlH₅ and NaBH₄ stages, respectively, as compared with the undoped 2NaAlH₄ + Ca(BH₄)₂ composite. During the dehydrogenation process, the formation of new active species of Al₃Ti together with CaF₂ played a vital role in accelerating the reactions in 5 wt% TiF₃ doped to the studied composite system.     

Direct synthesis of sodium alanate using mischmetal nanocatalyst

This study reports the synthesis of NaAlH₄ by ball milling of NaH and Al mixture along with 3 mol % Mischmetal (Mm) nanocatalyst under hydrogen atmosphere. It is observed that synthesis of the intermediate phase Na₃AlH₆ can be achieved by ball milling even under 1 atm hydrogen at room temperature. Ball milling of the NaH + Al with 3 mol % Mm with 3 atm hydrogen in excess of 40 h time did not lead to the formation of NaAlH₄ but charging of the milled material at 100 atm hydrogen pressure at 120 °C lead to formation of NaAlH₄ phase. Direct synthesis of NaAlH₄ was achieved by milling of NaH + Al with 3 mol % Mm under 100 atm hydrogen pressure. Direct synthesis is possible even without any catalyst by high pressure milling. However catalyst is required to improve the hydrogen sorption characteristics of the synthesized material. The as-prepared Mm catalyzed NaAlH₄ is also found to reversibly store hydrogen up to 4.2 wt% hydrogen. Catalytic activity is attributed to defects promoted by ball milling and catalysts.     

Al–Li3AlH6: A novel composite with high activity for hydrogen generation

A novel material for hydrogen generation with high capacity of H₂ generation has been successfully prepared by ball milling the mixture of Al and home-made fresh Li₃AlH₆ powder. Its theoretical capacity of hydrogen released is higher than that of pure Al. Results obtained have shown conversion efficiency of Al–Li₃AlH₆ composite can be close to 100% by increasing the content of Li₃AlH₆. When the content of Li₃AlH₆ is 20 wt%, the maximum hydrogen generation rate and hydrogen yield are 2737.6 mL g⁻¹ min⁻¹ and 1513.1 mL g⁻¹, respectively, at room temperature. By XRD, SEM analyses and reaction heat measurements, it demonstrates that the additive Li₃AlH₆ can provide an additional source of H₂ and an alkaline environment (LiOH) as well as additional heat to promote the Al/H₂O reaction. Therefore, the Al–Li₃AlH₆ composite has a very high activity and high capacity of hydrogen released.     

Hydrogen storage properties and mechanisms of the Mg(BH4)2–NaAlH4 system

Hydrogen storage properties and mechanisms of the combined Mg(BH₄)₂–NaAlH₄ system were investigated systematically. It was found that during ball milling, the Mg(BH₄)₂–xNaAlH₄ combination converted readily to the mixture of NaBH₄ and Mg(AlH₄)₂ with a metathesis reaction. The post-milled samples exhibited an apparent discrepancy in the hydrogen desorption behavior with respect to the pristine Mg(BH₄)₂ and NaAlH₄. Approximately 9.1 wt% of hydrogen was released from the Mg(BH₄)₂–2NaAlH₄ composite milled for 24 h with an onset temperature of 101 °C, which is lowered by 105 and 139 °C than that of NaAlH₄ and Mg(BH₄)₂, respectively. At initial heating stage, Mg(AlH₄)₂ decomposed first to produce MgH₂ and Al with hydrogen release. Further elevating operation temperatures gave rise to the reaction between MgH₂ and Al and the self-decomposition of MgH₂ to release more hydrogen and form the Al_0.9Mg_0.1 solid solution and Mg. Finally, NaBH₄ reacted with Mg and partial Al_0.9Mg_0.1 to liberate all of hydrogen and yield the resultant products of MgAlB₄, Al₃Mg₂ and Na. The dehydrogenated sample could take up ∼6.5 wt% of hydrogen at 400 °C and 100 atm of hydrogen pressure through a more complicated reaction process. The hydrogenated products consisted of NaBH₄, MgH₂ and Al, indicating that the presence of Mg(AlH₄)₂ is significantly favorable for reversible hydrogen storage in NaBH₄ at moderate temperature and hydrogen pressure.     

Excellent catalytic effect of LaNi5 on hydrogen storage properties for aluminium hydride at mild temperature

The catalytic effect of rare-earth hydrogen storage alloy is investigated for dehydrogenation of alane, which shows a significantly reduced onset dehydrogenation temperature (86 °C) with a high-purity hydrogen storage capacity of 8.6 wt% and an improved dehydrogenation kinetics property (6.3 wt% of dehydrogenation at 100 °C within 60 min). The related mechanism is that the catalytic sites on the surface of the hydrogen storage alloy and the hydrogen storage sites of the entire bulk phase of the hydrogen storage reduce the dehydrogenation temperature of AlH₃ and improve the dehydrogenation kinetic performance of AlH₃. This facile and effective method significantly improves the dehydrogenation of AlH₃ and provides a promising strategy for metal hydride modification.     

Dehydrogenation and rehydrogenation of a 0.62LiBH4-0.38NaBH4 mixture with nano-sized Ni

The dehydrogenation reaction pathway of a 0.91 (0.62LiBH₄-0.38NaBH₄)-0.09Ni mixture in the temperature range of 25–650 °C in flowing Ar and the cycling stability in H₂ are presented. No H₂ is released immediately after melting at 225 °C. The major dehydrogenation occurs above 350 °C. Adding nano-sized Ni reduces the dehydrogenation peak temperatures by 20–25 °C, leading to three decomposition steps where Ni₄B₃ and Li_1.2Ni_2.5B₂ are found in the major dehydrogenation products for the 1^st and the 3^rd step; whilst the Ni-free mixture decomposes through a two-step decomposition pathway. A total of 8.1 wt% of hydrogen release from the 0.91 (0.62LiBH₄-0.38NaBH₄)-0.09Ni mixture is achieved at 650 °C in Ar. This mixture has a poor hydrogen cycling stability as its reversible hydrogen content decreases from 5.1 wt% to 1.1 wt% and 0.6 wt% during three complete desorption-absorption-cycles. However, the addition of nano-sized Ni facilitates the reformation of LiBH₄.     

Decomposition of lithium magnesium aluminum hydride

The quaternary aluminum hydride LiMg(AlH₄)₃ contains 9.7 wt% hydrogen, of which 7.2 wt% can be released in a two-step decomposition reaction via first formation of LiMgAlH₆ and then the binary hydrides MgH₂ and LiH. In-situ synchrotron radiation powder X-ray diffraction and thermal desorption spectroscopy measurements were performed to analyze the product distributions formed during the thermal decomposition of LiMg(AlD₄)₃. The first decomposition step occurs at about 120 °C and the second at about 160 °C for the as-milled sample, while for a purified sample of LiMg(AlD₄)₃, the decomposition temperatures involving release of hydrogen increase to 140 and 190 °C, respectively, suggesting that pure samples of LiMg(AlD₄)₃ are kinetically stabilized. Studies of the purified LiMg(AlD₄)₃ also showed that the second decomposition step can be divided into two reactions: 3LiMgAlD₆ → Li₃AlD₆ + 3MgD₂ + 2Al + 3D₂ and Li₃AlD₆ → 3LiD + Al + 3/2D₂. Addition of TiCl₃ to LiMg(AlD₄)₃ under a variety of ball milling conditions consistently led to decomposition of LiMg(AlD₄)₃ during milling. Correspondingly, all attempts to rehydrogenate the (completely or partially) decomposed samples at up to 200 bar hydrogen pressure failed. Decomposition of MgD₂ was observed at relatively low temperatures. This is ascribed to thermodynamic destabilization due to the formation of different Al_xMg_y phases, and to kinetic destabilization by addition of TiCl₃. A thermodynamic assessment was established for the calculation of phase stability and decomposition reaction relationships within the Li-Mg-Al−H system. The calculations confirmed the metastability of the LiMg(AlH₄)₃ phase and the irreversibility of the Li-Mg alanate phase decomposition reactions. The Li-Mg alanate decomposition pathways followed experimentally could be explained by the endothermicity of the calculated decomposition enthalpies, in that an impure or catalyzed LiMgAlH₆ intermediate phase could more directly access an endothermic decomposition reaction at lower temperatures, while a kinetically-hindered, purified LiMgAlH₆ would require higher temperatures to initiate the two-step decomposition through an exothermic reaction.     

From the can to the tank: NaAlH4 from recycled aluminum

The recycling of Al-cans (from soft beverages cans) by a ball milling process and its use as a main component of a hydrogen storage material is presented. The recycled Al, together with NaH, TiF₃ as the catalyst, and C-nanotubes as milling agent were milled together as precursors of NaAlH₄. The material presented a reversible hydrogen storage capacity of 3.7 wt% at 150 °C and up to 100 bar hydrogen pressure. Characterization of the as-milled and hydrogenated materials indicates the feasibility of using Al recycled for producing NaAlH₄.     

Reversible hydrogen storage in a 3NaBH4/YF3 composite

A 3NaBH₄/YF₃ hydrogen storage composite was prepared through ball milling and its hydrogen sorption properties were investigated. It is shown that NaBH₄ does not react with YF₃ during ball milling. The dehydrogenation of the composite starts at 423 °C, which is about 100 °C lower than the dehydrogenation temperature of pure NaBH₄, with a mass loss of 4.12 wt%. Pressure–Composition–Temperature tests reveal that the composite has reversible hydrogen sorption performance in the temperature range from 350 °C to 413 °C and under quite low hydrogenation plateau pressures (<1 MPa). Its maximum hydrogen storage capacity can reach up to 3.52 wt%. The dehydrogenated composite can absorb 3.2 wt% of hydrogen within 5 min at 400 °C. Based on the Pressure–Composition–Temperature analyses, the hydrogenation enthalpy of the composite is determined to be −46.05 kJ/mol H₂, while the dehydrogenation enthalpy is 176.76 kJ/mol H₂. The mechanism of reversible hydrogen sorption in the composite involves the decomposition and regeneration of NaBH₄ through the reaction with YF₃. Therefore, the addition of the YF₃ to NaBH₄ as a reagent forms a reversible hydrogen storage composite.     

Synergistic enhancement of hydrogen storage properties in MgH2 using LiNbO3 catalyst

Extensive researches are being conducted to improve the high dehydrogenation temperature and sluggish hydrogen release rate of magnesium hydride (MgH₂) for better industrial application. In this study, LiNbO₃, a catalyst composed of alkali metal Li and transition metal Nb, was prepared through a direct one-step hydrothermal synthesis, which remarkably improved the hydrogen storage performance of MgH₂. With the addition of 6 wt% LiNbO₃ in MgH₂, the initial dehydrogenation temperature decreases from 300 °C to 228 °C, representing a drop of almost 72 °C compared to milled MgH₂. Additionally, the MgH₂-6 wt.% LiNbO₃ composite can quickly release 5.45 wt% of H₂ within 13 min at 250 °C, and absorbed about 3.5 wt% of H₂ within 30 min at 100 °C. It is also note that LiNbO₃ shows better catalytic effect compared to solely adding Li₂O or Nb₂O₅. Furthermore, the activation energy of MgH₂-6 wt.% LiNbO₃ decreased by 44.37% compared to milled MgH₂. The enhanced hydrogen storage performance of MgH₂ is attributed to the in situ formation of Nb-based oxides in the presence of LiNbO₃, which creates a multielement and multivalent chemical environment.     

Auto-ignited hydrogen combustor using NaBH4 thermal decomposition for ignition of aluminum powders

Auto-ignited hydrogen combustor using NaBH₄ thermal decomposition for ignition of aluminum powders was described. The NaBH₄ was thermally decomposed at 500 °C to generate hydrogen, and immediately the hydrogen was ignited because its auto-ignition temperature was 500 °C. The solid grain of NaBH₄ was prepared in a hollow shape and the air was supplied as an oxidizer for hydrogen auto-ignition. The effect of the air supply rate on the characteristics of the NaBH₄ thermal decomposition was evaluated. As a result, the decomposition efficiency was 95% and hydrogen flame was retained for 110 s with 30 g of NaBH₄. When the hydrogen flame was stabilized, aluminum powders was injected into the combustion zone with 1.268 g/min using the powder injector. The ignition of aluminum powders was successfully performed by the hydrogen combustor using the NaBH₄ thermal decomposition. The combustion of aluminum powders was validated by a photodetector equipped with a 486 nm filter for AlO radical detection.     

Enhancing hydrogen storage performance of MgH2 through the addition of BaMnO3 synthesized via solid-state method

Currently, magnesium hydride (MgH₂) as a solid-state hydrogen storage material has become the subject of major research owing to its good reversibility, large hydrogen storage capacity (7.6 wt%) and affordability. However, MgH₂ has a high decomposition temperature (>400 °C) and slow desorption and absorption kinetics. In this work, BaMnO₃ was synthesized using the solid-state method and was used as an additive to overcome the drawbacks of MgH₂. Interestingly, after adding 10 wt% of BaMnO₃, the initial desorption temperature of MgH₂ decreased to 282 °C, which was 138 °C lower than that of pure MgH₂ and 61 °C lower than that of milled MgH₂. For absorption kinetics, at 250 °C in 2 min, 10 wt% of BaMnO₃-doped MgH₂ absorbed 5.22 wt% of H₂ compared to milled MgH₂ (3.48 wt%). Conversely, the desorption kinetics also demonstrated that 10 wt% of BaMnO₃-doped MgH₂ samples desorbed 5.36 wt% of H₂ at 300 °C within 1 h whereas milled MgH₂ only released less than 0.32 wt% of H₂. The activation energy was lowered by 45 kJ/mol compared to that of MgH₂ after the addition of 10 wt% of BaMnO₃. Further analyzed by using XRD revealed that the formation of Mg_0·9Mn_0·1O, Mn₃O₄ and Ba or Ba-containing enhanced the performance of MgH₂.     

Mechanochemical synthesis and dehydrogenation properties of Yb(AlH4)3

The facile synthesis of ytterbium tetrahydroaluminate Yb(AlH₄)₃ is conducted by a mechanochemical procedure under hydrogen atmosphere for the first time. Results show that the synthesized Yb(AlH₄)₃ remains as an amorphous state. The thermal decomposition of Yb(AlH₄)₃ goes through a four-stage pathway with several amorphous intermediate phases during the process. The first dehydrogenation step of Yb(AlH₄)₃ presents a relatively low apparent activation energy of 99.6 kJ mol^?1, and ninety percent of the hydrogen from this stage can be liberated within 20 min at 160 ^°C. Rehydrogenation tests above 160 ^°C and 14 MPa hydrogen pressure demonstrate the unsuccessful rehydrogenations of the first decomposition step due to the formation of a thermodynamically more stable compound YbHCl.     

Catalytic effect of MgFe2O4 on the hydrogen storage properties of Na3AlH6–LiBH4 composite system

The effect of MgFe₂O₄ on the hydrogen storage properties of the composite Na₃AlH₆4LiBH₄ was studied for the first time, where it was found that MgFe₂O₄ addition decreased the onset desorption temperature of Na₃AlH₆4LiBH₄. Hydrogen (～9.5 wt%) was released in three stages and the dehydrogenation temperatures were reduced to 80 °C, 350 °C, and 430 °C for the first, second, and third stage, respectively. The absorption kinetics of Na₃AlH₆4LiBH₄ was also significantly improved due to the catalytic effect of MgFe₂O₄. Using Kissinger analysis, the apparent activation energies of decomposition of the Li₃AlH₆ and NaBH₄ stages in Na₃AlH₆4LiBH₄-10 wt% MgFe₂O₄ were calculated to be 72 and 141 kJ/mol, respectively. These values were considerably lower than the corresponding values for the undoped composite. X-ray diffraction analysis revealed the formation of new products such as MgO and Fe during the heating process. Our results suggest that MgFe₂O₄ enhanced the hydrogen storage properties of Na₃AlH₆4LiBH₄ through the formation of active species, such as MgO and Fe.     

Catalytic effects of MgFe2O4 addition on the dehydrogenation properties of LiAlH4

Study on the catalytic roles of MgFe₂O₄ on the dehydrogenation performance of LiAlH₄ was carried out for the first time. Notable improvement on the dehydrogenation of LiAlH₄–MgFe₂O₄ compound was observed. The initial decomposition temperatures for the catalyzed LiAlH₄ 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 LiAlH₄. As for the desorption kinetics performance, the MgFe₂O₄ doped-LiAlH₄ sample was able to desorb faster with a value of 3.5 wt% of hydrogen in 30 min (90 °C) while the undoped LiAlH₄ 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 LiAlH₄. The X-ray diffraction result suggested that the MgFe₂O₄ had promoted significant improvements by reducing the LiAlH₄ decomposition temperature and faster desorption kinetics through the formation of active species of Fe, LiFeO₂ and MgO that were formed during the heating process.     

Phase-structural and morphological features,dehydrogenation/re-hydrogenation performance and hydrolysis of nanocomposites prepared by ball milling of MgH2 with germanium

Ball milling of magnesium hydride with germanium additives in argon for up to 10 h was shown to result in the formation of nanocomposites of α- and γ-modifications of MgH₂ together with individual Ge phase. When the as milled samples are heated-up, Ge interacts with MgH₂ to form Mg₂Ge at T = 350–400 °C; the phase transformation overlaps with MgH₂ decomposition and Mg₂Ge phase remains in the material after its re-hydrogenation at T = 300 °C and P(H₂)∼15 bar.The ball milled Ge-MgH₂ nanocomposites were found to be characterised by an improved hydrogen release via hydrolysis in organic acid solutions as compared to pure MgH₂ prepared and tested at the same conditions. It was found that the composite containing 5 wt% of Ge and ball milled for 5 h showed the best hydrogen generation performance, with total hydrogen release exceeding 1.55 NL/g (yield close to 100%) in one minute.