Hydrogen Storage Properties Of MgH2 Research Articles

Effects of heteroatom-doped hierarchical porous carbon on hydrogen storage properties of MgH2

In this paper, the nitrogen doped (N-HPC), nitrogen and phosphorus co-doped hierarchical porous carbon (NP-HPC) are prepared by cross-linking phytic acid and poly pyrrole/aniline precursor, respectively. They are mixed with MgH2 by high-energy ball milling, and then their effects and mechanisms on the hydrogen absorption and desorption properties of MgH2 are investigated. Meanwhile, the hydrogen storage properties of MgH2 added with graphite (G) are also compared. The results show that the additions of NP-HPC, N-HPC, and G all exhibit the catalytic effect on the hydrogen absorption and desorption of MgH2. As for the hydrogen desorption, the catalytic effect is enhanced in the order of N-HPC, G and NP-HPC. Compared with pure MgH2, the hydrogen desorption temperature is reduced by 65.3 °C, 79.6 °C and 91.1 °C, respectively. Among them, the MgH2 + NP-HPC system can release 5.17 wt% hydrogen at 300 °C within 30 min. First-principles calculations reveal that the P-doped and vacancy-containing carbon materials significantly reduce the H2 recombination barrier from the surface of MgH2 and distort the atomic structure of near-surface layer of MgH2, which in turn weakens the Mg-H bond strength. This may be the intrinsic reason for the excellent catalytic effect of NP-HPC and vacancy-containing G on the hydrogen desorption performance of MgH2.

Catalytic modification of MgH2 hydrogen storage properties by La–Ni catalysts

In this paper, it is experimentally demonstrated that the La–Ni catalyst contributes to the hydrogen storage performance of MgH2. Firstly, La–Ni (La: Ni = 1: 5.7) catalysts are prepared by CaH2 reduction method, and then MgH2+x wt.% La–Ni (x = 0, 3, 5, 7) composite alloys were prepared by ball milling method. The present work focuses on the structural and hydrogen ab/desorption properties of the composite alloys, and analysis the modulatory effect and influence mechanism of different La–Ni catalyst additions on the hydrogen storage properties of MgH2. The findings show that the composite alloys have the same diffraction peaks and that the main phase of the composite alloys is the MgH2 phase, with the addition of the LaNi5 phase, the Mg2Ni phase and a small amount of Mg phase. The mutual reversible transformations of LaH3 and Mg2Ni and Mg2NiH4 play a catalytic role in the hydrogen ab/desorption process. Moreover, the addition of La–Ni catalyst plays a dramatic improvement effect on the kinetic performance of MgH2 ab/desorption. When the addition of La–Ni catalyst is 5 wt.%, the composite alloy exhibits the most excellent hydrogen uptake and release kinetics. The MgH2+5 wt.% La–Ni composite alloy absorbs 4.2 wt.% H2 within 2 min at 473 K and releases 3.43 wt.% H2 within 150 min at 503 K. Fitting the hydrogen release activation energy of the composite alloys shows that the hydrogen release activation energy of the composite alloys decreases first and then increases, and there is a minimum hydrogen release activation energy of 101.81 kJ/mol H2 when the addition amount x = 5 wt.%.

In-situ formation of V and Mg2Co/Mg2CoH5 for boosting the hydrogen storage properties of MgH2

Among the potential candidates for solid-state hydrogen storage, magnesium hydride (MgH2) exhibits high storage capacity of 7.6 wt%. However, its commercial application is hindered by the unsatisfactory kinetics properties and stable thermodynamics. In this study, we synthesized porous spherical CoV₂O₆ and incorporated it into MgH2, reducing the initial dehydrogenation temperature of MgH2 to 190 °C. Additionally, rapid hydrogen uptake was also observed, approaching 6.5 wt% H2 within 1000 s at 190 °C. A notable decrease of 45.78 kJ/mol in the apparent activation energy (Ea) for dehydrogenation signifies an improved dehydrogenation kinetic. The formation of Mg2Co/Mg2CoH5, along with the presence of single-valence and multi-valence vanadium, facilitated multiple electron transfer pathways. In particular, vanadium elongated the Mg–H bond is responsible for the high catalytic activity in boosting the hydrogen storage performance of MgH2. These findings provide new intuitions for further research to enhance the kinetic properties of hydrogen adsorption and desorption in magnesium hydride.

Enhancing hydrogen storage properties of MgH2 via reaction-induced construction of Ti/Co/Mn-based multiphase catalytic system

The inherent kinetic limitations and high operating temperatures of magnesium hydride (MgH2) hinder its practical applications. Herein, we report the successful synthesis of a TiO2@MnCo2O4.5 composite transition metal oxide catalyst and investigate its effect on the hydrogen storage performance of MgH2. TiO2@MnCo2O4.5 exhibits exceptional catalytic activity in the hydrogen dissociation and recombination reactions of during absorption and desorption processes, reducing the dehydrogenation activation energy of MgH2 to 75.54 kJ/mol. Notably, the MgH2-6 wt% TiO2@MnCo2O4.5 system releases 6.04 wt% H2 within 30 min at 250 °C, and 4.98 wt% H2 within 120 min at 225 °C. Furthermore, it can absorb 5.08 wt% H2 within 3 min at 150 °C and achieve a hydrogen absorption capacity of 2.02 wt% within 30 min even at 30 °C. The reaction-induced decomposition and phase transformation of TiO2@MnCo2O4.5 create a multiphase, multi-site catalytic environment. The hydrogen storage system based on the coexistence of Mg6MnO8, Mn, Ti2O3, and CoO features abundant diffusion pathways and nucleation sites, playing a critical role in suppressing the energy barriers for MgH2 hydrogen absorption and desorption reactions. These findings provide a meaningful theoretical foundation for the microstructural optimization and performance regulation of Mg-based hydrogen storage materials.

Introducing 2D layered WS2 and MoS2 as an active catalyst to enhance the hydrogen storage properties of MgH2

The current work describes how 2D layered materials, such as MoS2 and WS2, might improve the de/re-hydrogenation kinetics of MgH2. In the presence of WS2 catalyst, desorption of MgH2 begins at 277 °C, with a hydrogen storage capacity of 5.95 wt%, while the onset desorption temperature of MgH2 catalyzed by MoS2 is 330 °C. In just 1.3 min at 300 °C under 13 atm hydrogen pressure, the MgH2-WS2 absorbed approximately 3.72 wt% of hydrogen, and in 20 min at 300 °C under 1 atm hydrogen pressure, it desorbed around ∼5.57 wt% of hydrogen. To ensure the cyclic stability up to 25 cycles of de/re-hydrogenation of the catalyzed MgH2, a continuously 25 cycles of dehydrogenation (under 1 atm hydrogen pressure at 300 °C) and rehydrogenation (under 13 atm hydrogen pressure at 300 °C) were carried out. As a result, MgH2-WS2 exhibits superior cyclic stability than MgH2–MoS2. In addition, with the de/re-hydrogenation kinetics, MgH2-WS2 has a lower reaction activation energy (∼117 kJ/mol) than to other catalyzed and pristine samples. Conversely, the thermodynamical parameters, specifically the change in enthalpy of MgH2, are unaffected by addition of these layered WS2 and MoS2 catalysts.

Facilitated hydrogen storage properties of MgH2 by Ni nanoparticles anchored on Mo2C@C nanosheets

Magnesium hydride (MgH2) holds promise as a hydrogen storage material, but its practical application is impeded by high desorption temperatures and slow kinetics, presenting substantial challenges. Herein, an efficient approach is proposed to synthesize Mo2C@C nanosheets-supported Ni nanoparticles (Ni/Mo2C@C-2) materials, which can operate as a highly efficient catalyst to enhance hydrogen desorption of MgH2. The ball-milled MgH2–7.5 wt% Ni/Mo2C@C-2 demonstrates prominent hydrogen desorption kinetics with an activation energy (Ea) of 97.22 kJ mol−1, alongside remarkable cycling stability, maintaining a capacity retention of 97.8% after 20 cycles. Consequently, the results reveal that the improvement of hydrogen storage properties for MgH2 can be attributed to the synergistic effect of the in-situ generated Mg2NiH4 with highly dispersion, the sustained Mo2C nanosheets, and highly graphitized carbon. This work provides a reliable strategy for constructing polyoxometalates derivatives to facilitate the hydrogen desorption and cycling of MgH2.

Effect of Ce0.6Zr0.4O2 nanocrystals on boosting hydrogen storage performance of MgH2

Magnesium hydride (MgH2) has been widely recognized as a highly promising solid-state media for hydrogen storage. However, the high operating temperature and the intrinsic sluggish kinetics hinder the practical application as a portable solid storage carrier. To address this issue, we have successfully fabricated a novel rare earth-containing bimetallic oxide additive, namely Ce0.6Zr0.4O2 nanocrystals, which exhibits a significant catalytic effect in enhancing the hydrogen storage properties of MgH2. By incorporating 7 wt% Ce0.6Zr0.4O2 into MgH2, the modified composite releases hydrogen as low as 201 °C. Furthermore, in an isothermal dehydrogenation test conducted at 270 °C for 8 min, approximately 6.15 wt% of H2 was desorbed. The composites can rapidly recharge hydrogen at a low temperature of 50 °C and 6.02 wt% H2 being absorbed within 3 min at 150 °C under 50.0 bar. Comparatively, the dehydrogenation activation energy of the Ce0.6Zr0.4O2-modified MgH2 significantly decreased compared to MgH2 by ball milling. In addition to its improved hydrogen storage properties, the composite also exhibits excellent cycling stability. Through cyclic de-/rehydrogenation experiments conducted at 270 °C, a capacity retention of 98.9 % was achieved over 20 cycles. This exceptional performance can be attributed to the in-situ formation of the CeH2.73/CeO2-x and ZrO2, which originated from the Ce0.6Zr0.4O2 additive following the first de-/rehydrogenation cycle. The uniform dispersion of the multiphase component nano-sized active species within the MgH2 matrix facilitates charge transfer and accelerates hydrogen diffusion. Density functional theory calculations revealed the dissociation energy barrier and dissociation energy of H2 were alleviated by integrating Zr into CeO2. This work provides valuable insights for further rational designs of novel catalysts by transition metals and rare earths in promoting the commercialization of MgH2.

Hydrogen storage properties of MgH2 + Mg2NiH4–Co/C ternary nanocomposite

The application of ternary nanocomposite synergetic catalysis has proven to be an effective modification strategy for enhancing MgH2 hydrogen storage performance. The ternary magnesium-based hydrogen storage alloy, composed of MgH2+Mg2NiH4–Co/C, is successfully prepared and characterized. Through the optimized preparation process and the optimal ratio, it is observed that the catalyst Mg2NiH4–Co/C significantly reduces the reaction activation energy, resulting in a the initial hydrogen desorption temperature is approximately 60 °C lower than that of pure MgH2. The enhanced hydrogen storage properties are attributed to the synergistic catalytic effect of carbon (C) combined with the formation of Mg2Ni and Mg2Co facilitated by Ni and Co elements. Furthermore, the reversible phase transitions of Mg2Co/Mg2CoH5 and Mg2Ni/Mg2NiH4 serve as "hydrogen pumps" further aiding in hydrogen storage. This study extends the investigation of the synergistic catalytic effect of ternary nanocomposites to enhance the hydrogen storage performance of alloys.

Improved in hydrogen storage properties of MgH2 catalyzed by as-prepared Graphene oxide-supported SnO2 nanoparticles

Improved in hydrogen storage properties of MgH2 catalyzed by as-prepared Graphene oxide-supported SnO2 nanoparticles

Introducing Ni-N-C ternary nanocomposite as an active material to enhance the hydrogen storage properties of MgH2

The use of Mg-based materials as solid-state hydrogen storage materials can provide a viable solution to the bottleneck hindering the development of hydrogen energy. However, it is necessary to address their excessively stable thermodynamic properties and sluggish kinetic performances. In this study, we prepared a Ni-N-C ternary nanocomposite (designated as Ni@NC) catalyst using Ni-based metal-organic frameworks (Ni-MOFs) as a precursor for catalytic MgH2 hydrogen storage properties. The Ni@NC catalyst exhibited excellent promotion effects on the hydrogen absorption and desorption kinetics and the cycling stability of the Mg-based materials. Notably, the composite exhibited room-temperature hydrogen absorption initiation and an onset dehydrogenation temperature of 188 °C, with complete hydrogenation achieved after holding at 100 °C for 60 min. After undergoing 100 cycles of absorption/dehydrogenation, the capacity retention rate was 99.5 %. The differential scanning calorimetry (DSC) test results indicated that the re-hydrogenated MgH2-Ni@NC composites consist of Mg2NiH4 and MgH2, with corresponding dehydrogenation activation energies of 75.2 and 82.9 kJ mol−1 respectively. The mechanism analysis revealed that Ni@NC was uniformly distributed on the MgH2 surface. During dehydrogenation/rehydrogenation, Mg2NiH4/Mg2Ni “hydrogen pumping” by Ni and MgH2/Mg occurred in situ, the presence of N-C effectively inhibited the expansion of MgH2/Mg, and the enhanced charge transfer effect was facilitated by N in the Ni@NC composite, synergistically enhancing the kinetic performance and cycling stability of MgH2.

Effect of MOF-derived nanoparticle-cumulated flower-like CoFe@C coated composites on hydrogenation/dehydrogenation performance of MgH2

Magnesium hydride (MgH2) has garnered substantial consideration mainly due to its high gravimetric density and reliable resource, whereas its poor thermodynamics and kinetics for absorbing/releasing hydrogen restricts the largescale application. Certain catalysts have demonstrated remarkable activity in enhancing the hydrogen storage capabilities of MgH2. In this work, the nanoparticle-cumulated flower-like CoFe@C coated catalysts (denoted as CoFe@C) are controllably synthesized as expected by the MOF (Metal-Organic Farmwork) in-suit decomposition method at 800 °C, which exhibits an average pore size of 18.63 nm. Meanwhile, the particle size for the as-prepared CoFe alloy coated in carbon layer are approximately 10–20 nm, and the as-prepared samples are introduced to promote the de/rehydrogenation properties of MgH2 at relatively lower temperatures. Due to the synergistic interaction of CoFe alloy nanoparticles serving as active sites and agglomeration resistance of carbon layers, the MgH2 composites doped with CoFe@C-800 could initialize its decomposition process at 175.9 °C, and may desorb 6.0 wt% H2 at 300 °C in 400 s. Additionally, the peak temperature and apparent activation energy during dehydrogenation decline significantly (with 35 % and 38 %, respectively). Furthermore, theoretical analysis results indicate a higher catalytic activity for the carbon-coated CoFe alloy owing to the synergetic effect between CoFe nanocomposite & carbon layer, which can facilitate the bond extension and strength decrease of Mg-H bonding. In brief, using MOF may derive transition metal and carbon layer, which could be a promising approach to stimulating the hydrogen storage properties of MgH2.

Hydrogen storage properties of MgH2 modified by efficient Co3V2O8 catalyst

Developing medium temperature hydrogen storage materials is important for the practical application of the Studies have demonstrated that V-based catalysts exhibit exceptional catalytic activity in the dehydrogenation of MgH2 at medium levels. However, the V-base catalysts primarily concentrates on hydrogen desorption, and there is a necessity for further enhancement of hydrogen absorption properties. To solve this problem, herein we prepared a bimetallic oxide. Co can enhance the hydrogen absorption and desorption properties of MgH2 as the catalyst and it influences the performance of hydrogen absorption more obviously than the hydrogen desorption performance. It is found that MgH2 catalyzed by Co3V2O8 can absorb 1.31 wt% hydrogen within 30 min even under room temperature and can release 3.41 wt% hydrogen within 120 min at temperatures as low as 225 °C. The activation energy of MgH2-6 wt.%Co3V2O8 is determined to 68.5 kJ/mol, which is 50.2 % lower than that of Ball-MgH2. XRD combined with TEM measurements revealed that the in-situ formed Co and V2O3 can weaken the HH and MgH bonds respectively to improve the hydrogen storage properties of MgH2. These discoveries provide guideline of the further design of high efficiency catalysts for Mg-based hydrogen storage materials.

Improvement in the Hydrogen Storage Properties of MgH2 by Adding NaAlH4

Milled MgH2, MgH2-10NaAlH4, MgH2-30NaAlH4, MgH2-50NaAlH4, and MgH2-2Ni-10NaAlH4 samples were prepared by milling in a planetary ball mill in hydrogen atmosphere (reactive mechanical milling, RMM). Decomposition temperatures of milled MgH2, NaAlH4, MgH2-10NaAlH4, and MgH2-30NaAlH4 were examined in a Sieverts-type hydrogen absorption and release apparatus, in which the hydrogen pressures were kept nearly constant during hydrogen absorption or release. As the content of NaAlH4 in the sample increased, the temperature at the highest peak in the ratio of increase in released hydrogen quantity to increase in temperature versus temperature curve decreased. Hydriding in 12 bar hydrogen and dehydriding in 1.0 bar hydrogen at 593 K of MgH2-30NaAlH4 are performed by the reversible reactions MgH2 ⇔ Mg + H2 and 17MgH2 + 12Al ⇔ Mg17Al12 + 17H2. MgH2-30NaAlH4 was the best Mg-based composite among Mg-based alloys in which an oxide, a halide, a fluoride, or a complex hydride was added, with a high hydrogen absorption rate for 2.5 min (2.20 wt% H/min) and a large effective hydrogen storage capacity (7.42 wt% H).

Fabrication of amorphous TiO2 hydrogen channels and graphene wrappers to enhance the hydrogen storage properties of MgH2 with extremely high cycle stability

Amorphous TiO2 hydrogen channels and graphene wrappers to enhance the hydrogen storage performance.

Effect of Ti0.9Zr0.1Mn1.5V0.3 alloy catalyst on hydrogen storage kinetics and cycling stability of magnesium hydride

As a high-capacity hydrogen storage material, MgH2 still has the problem of high operating temperature and slow reaction kinetics. In this work, an TiMn2-based Laves phase alloy (Ti0.9Zr0.1Mn1.5V0.3, denoted as Ti–Mn) was first synthesized by arc melting and then employed to regulate the hydrogen storage properties of MgH2, with the carbon nanotubes (CNTs) as an aid agent to facilitate the hydrogen diffusion and heat transfer. It was shown that the introduction of Ti–Mn/CNTs can remarkably improve the hydrogen storage properties of MgH2. The MgH2 + 10 wt% Ti–Mn + 1 wt% CNTs composite has an initial dehydrogenation temperature of 195 °C and can absorb hydrogen at room temperature. As for the kinetics, it can release 6.1 wt% H2 in 5 min at 300 °C, and absorb 4.8 wt% H2 in 10 min at 150 °C. It still has a reversible capacity of 6.2 wt% after 100 cycles. Combination of Ti–Mn alloy and CNTs is more effective than Ti–Mn alloy or CNTs alone for regulating MgH2. Ti–Mn/CNTs does not alter the overall thermodynamics of MgH2. However, local destabilization of Mg–H bonds induced by the MgH2/Ti–Mn interfaces was observed experimentally and confirmed theoretically, which partially contributes to the enhanced hydrogen storage of MgH2. In addition, the active transition metals contained in the alloy was believed to accelerate the hydrogen dissociation and delivery during the hydrogen storage process. This work not only achieves the synergistic improvement of hydrogen storage of MgH2 by combination of Ti–Mn alloy and CNTs, but also presents the local destabilization mechanism to explain the improved hydrogen storage of MgH2 by Ti–Mn alloy experimentally and theoretically.

Layered double hydroxide-derived Mg2Ni/TiH1.5 composite catalysts for enhancing hydrogen storage performance of MgH2

Developing efficient catalysts is of great significance in improving the sluggish kinetics and high desorption temperature of MgH2 hydrogen storage material. Here, ultrathin NiTi-layered double hydroxide (NiTi-LDH) nanosheets are used as precursors to prepare Mg2Ni/TiH1.5 composite catalysts to improve the hydrogen storage properties of MgH2. The variation of Ni/Ti ratio in LDH plays an important role in regulating the composition, morphology and distribution of Mg2Ni/TiH1.5 catalysts, which significantly affect their synergistic catalytic effect. Mg2Ni/TiH1.5 composite catalyst exhibits significantly improved catalytic performance compared with conventional Ni-, Ti- and Ni/Ti-based catalysts. The optimal MgH2/Mg2Ni/TiH1.5 system shows a significantly reduced desorption temperature of 212 °C which is 133 °C lower than that of pure MgH2 (345 °C), and can release 5.97 wt% hydrogen within 300s at 300 °C. Further mechanism analysis reveals that the unique flaky morphology and suitable composition of Ni/Ti LDH can significantly enhance the synergistic effect of Mg2Ni and TiH1.5, which promotes the fracture of the HH and Mg-H bonds.

Catalytic effect of double transition metal sulfide NiCo2S4 on hydrogen storage properties of MgH2

The limited practicality of magnesium hydride (MgH2) is due to its remarkable thermodynamic steadiness and sluggish hydrogen (H2) storage rate. In this study, NiCo2S4, a double transition metal sulfide, was synthesized and used to promote the kinetic properties of MgH2. Starting release temperature of MgH2- 10 NiCo2S4 composite is 203 °C. MgH2-10 NiCo2S4 composite releases 6.11 wt% H2 in 5 min at 325 °C, and absorbs 5.54 wt% H2 in 1 min at 150 °C. Besides, the Arrhenius equation yields the activation energy (Ea) of MgH2-10 NiCo2S4 composite to be 86.50 ± 2.00 kJ/mol. It is noteworthy that the MgH2-10 NiCo2S4 composite generated MgS, Mg2Ni and Mg2Co in situ active species during the first dehydrogenation process. The synergistic effect between the MgS, Mg2Ni/Mg2NiH4 and Mg2Co/Mg2CoH5 multiphase catalytic systems was generated in the cycle, which observably boosted the kinetics of Mg/MgH2.

(TiVZrNb)83Cr17 high-entropy alloy as catalyst for hydrogen storage in MgH2

High-entropy alloys (HEAs) hold the promise as excellent catalysts to improve the hydrogen storage properties of MgH2 due to their distinctive compositional and structural characteristics and superior room-temperature hydrogen storage performance. In this work, the (TiVZrNb)83Cr17 HEA was successfully designed and synthesized. Moreover, different amounts of the (TiVZrNb)83Cr17 HEA were introduced into MgH2 as catalysts by ball milling to prepare MgH2-x wt% (TiVZrNb)83Cr17 (x = 3, 6, 10) composites. MgH2-6 wt% (TiVZrNb)83Cr17 composite showed excellent hydrogen absorption and desorption properties. At 573 K, the composite can rapidly absorb 5.3 wt% H2 within 5 min, and even at 523 K, it can still absorb 4.0 wt% H2 within 60 min. Also, it can rapidly desorb 6.0 wt% and 4.1 wt% H2 within 60 min at 623 K and 573 K, respectively. In addition, the MgH2-6 wt% (TiVZrNb)83Cr17 composite possessed relatively low activation energy for hydrogen absorption (70.6 kJ/mol H2) and desorption (90.5 kJ/mol H2). Moreover, the capacity retention was as high as 98.5 % after 10 hydrogen de/absorption cycles at 573 K. Interestingly, (TiVZrNb)83Cr17 HEA transformed from the as-prepared biphasic structure (FCC + BCC) to the hydrogenated single-phase structure (FCC) in the hydrogenation process and returned to the initially biphasic structure (FCC + BCC) in the desorption process, which provided more diffusion pathways for H and more nucleation sites for Mg/MgH2. The multi-element (TiVZrNb)83Cr17 HEA catalyst realized the synergistic catalysis of the hydrogen ab/de-sorption of Mg/MgH2. Our findings provide useful insights into the design and development of HEAs catalysts for improving the hydrogen storage properties of MgH2.

Enhanced hydrogen storage properties of MgH2 with the co-addition of LiBH4 and YNi5 alloy

MgH2, as one of the typical solid-state hydrogen storage materials, has attracted extensive attention. However, the slow kinetics and poor cycle stability limit its application. In this work, LiBH4 and YNi5 alloy were co-added as additives to MgH2 via ball milling, thereby realizing an excellent dehydrogenation performance and good cycle stability at 300 °C. The MgH2-0.04LiBH4-0.01YNi5 composite can release 7 wt.% of hydrogen in around 10 min at 300 °C and still have a reversible hydrogen storage capacity of 6.42 wt.% after 110 cycles, with a capacity retention rate as high as 90.3 % based on the second dehydrogenation capacity. The FTIR results show that LiBH4 can reversibly absorb and desorb hydrogen throughout the hydrogen ab/desorption process, which contributes a portion of the reversible hydrogen storage capacity to the MgH2-0.04LiBH4-0.01YNi5 composite. Due to the small amount of LiBH4 and YNi5, the dehydrogenation activation energy of MgH2 did not decrease significantly, nor did the dehydrogenation enthalpy (∆H) change. However, the MgNi3B2 and in-situ formed YH3 during the hydrogen absorption/desorption cycles is not only beneficial to the improvement of the kinetics performance for MgH2 but also improves its cycle stability. This work provides a straightforward method for developing high reversible hydrogen capacity on Mg-based hydrogen storage materials with moderate kinetic performance.

Improved hydrogen storage properties of MgH2 by Mxene (Ti3C2) supported MnO2

MgH2 is a promising high-capacity solid hydrogen storage material. In this work, MnO2-doped Ti3C2 (Ti3C2@MnO2) was synthesized and used as a catalyst to improve the hydrogen storage performance of MgH2. We found that the dehydrogenated 10 wt% Ti3C2@MnO2-doped MgH2 sample exhibited good hydrogen adsorption ability even at room temperature (30 °C), and could absorb 5.13 wt% of hydrogen in 400 s at 75 °C. The re‑hydrogenated Ti3C2@MnO2-doped MgH2 sample started to release hydrogen at 182 °C and required 484 s to completely release hydrogen at 275 °C with a dehydrogenation capacity of 6.4 wt%. The Ti3C2@MnO2 composite did not change the thermodynamic properties of MgH2. In the MgH2 + Ti3C2@MnO2 sample, Ti3C2, TiO2, MnO2, MnO, and Mn combined with MgH2 to form Ti3C2/MgH2, TiO2/MgH2, MnO2/MgH2, MnO/MgH2, and Mn/MgH2 multiphase interfaces, which improved the hydrogen storage performance of MgH2. The findings of this work may provide a new strategy for preparing novel and efficient catalysts for hydrogen storage applications.