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Magnesium hydride (MgH 2) is the most prominent carrier for storing hydrogen in solid-state mode. However, their slow kinetics and high thermodynamics become an obstacle in hydrogen storage. The present study elaborates on the catalytic effect of graphene (Gr) and vanadium disulfide (VS 2) on MgH 2 to enhance its hydrogen sorption kinetic. The temperature-programmed desorption study shows that the onset desorption temperature of MgH 2 catalyzed by VS 2 and MgH 2 catalyzed by Gr is 289 °C and 300 °C, respectively. These desorption temperatures are 87 °C and 76 °C lower than the desorption temperature of pristine MgH 2. The rapid rehydrogenation kinetics for the MgH 2 catalyzed by VS 2 have been found at a temperature of 300 °C under 15 atm H 2 pressure by absorbing ∼4.04 wt% of hydrogen within 1 min, whereas the MgH 2 catalyzed by Gr takes ∼3 min for absorbing the same amount of hydrogen under the similar temperature and pressure conditions. The faster release of hydrogen was also observed in MgH 2 catalyzed by VS 2 than MgH 2 catalyzed by Gr and pristine MgH 2. MgH 2 catalyzed by VS 2 releases ∼2.54 wt% of hydrogen within 10 min, while MgH 2 catalyzed by Gr takes ∼30 min to release the same amount of hydrogen. Furthermore, MgH 2 catalyzed by VS 2 also persists in the excellent cyclic stability and reversibility up to 25 cycles. • Synthesis of MgH 2 catalyzed by 2-D materials (graphene and VS 2). • Enhanced hydrogen sorption kinetics of MgH 2 in the presence of VS 2 catalyst. • Highly cyclic stable during de/re-hydrogenation up to 25 cycles. [ABSTRACT FROM AUTHOR]

The complex hydride NaAlH 4 remains the archetype hydrogen storage system. In this paper, we have explored the catalytic action of Al 65 Cu 20 Fe 15 quasicrystal (QC) on the de/re-hydrogenation study of NaAlH 4. The leached ball-milled Al 65 Cu 20 Fe 15 (LBMACF) catalyzed NaAlH 4 sample has shown a lower hydrogen desorption temperature (140 °C) than other catalyzed and uncatalyzed NaAlH 4 samples. NaAlH 4 -LBMACF rapidly absorbed ∼3.20 wt% of hydrogen within 1 min and absorbed maximum capacity (∼4.68 wt%) in 15 min, while NaAlH 4 -LACF, NaAlH 4 -BMACF, NaAlH 4 -ACF, and pristine NaAlH 4 absorbed only 0.50 wt%, 1.38 wt%, 1.10 wt%, and 0.70 wt% in 1 min at 130 °C under 100 atm hydrogen pressure. NaAlH 4 -LBMACF has desorbed ∼4.22 wt% of hydrogen within 15 min, while the same amount of hydrogen desorbed by NaAlH 4 -LACF takes 45 min at 130 °C under 1 atm hydrogen pressure. NaAlH 4 -LBMACF shows reversibility up to 25 cycles with minimum degradation of hydrogen storage capacity of ∼0.06 wt% during de/re-hydrogenation. The catalytic mechanism and catalytic effect of Al–Cu–Fe on the NaAlH4 have been discussed using structural, microstructural analysis, in-situ nuclear magnetic resonance (NMR) spectroscopy, in-situ Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). • Al–Cu–Fe quasicrystal and its modified versions have explored as catalyst. • Mechanistic understanding of catalytic behavior of Al 65 Cu 20 Fe 15 quasicrystal. • NaAlH 4 -LBMACF absorbed ∼3.20 wt% of hydrogen within 1 min and desorbed ∼4.22 wt% of hydrogen within 15 min. • Excellent reversibility and cyclic stability of NaAlH 4 -LBMACF sample up to 25 cycles. [ABSTRACT FROM AUTHOR]

Summary: Magnesium hydride (MgH2) has received much attention as a solid‐state hydrogen storage material worldwide due to its high hydrogen storage capacity, good reversibility, and low cost. However, its practical application has been limited due to its high thermodynamic stability and slow kinetics. In the present work, we have employed a new type of catalyst, Titanium‐tetra‐isopropoxide (TTIP) (Ti(OC3H7)4), to catalyze MgH2. To disperse the catalyst evenly over the MgH2, the milling operation was conducted using tetrahydrofuran (THF) as a process control agent. Here, using THF as the process control agent during the wet ball milling along with TTIP of MgH2 itself used to improve the de/re‐hydrogenation behavior of MgH2. A de/re‐hydrogenation investigation demonstrates that MgH2 catalyzed by TTIP has better hydrogen storage properties (onset dehydrogenation temperature 210°C) than as‐cast MgH2 (onset dehydrogenation temperature ~400°C). Furthermore, a remarkable catalytic behavior of TTIP on MgH2 was observed during de‐/re‐hydrogenation kinetics (absorb the hydrogen ~4.6 wt% within the 1.5 minutes at a temperature of 300°C under a hydrogen pressure of 20 atm and release the hydrogen of ∼4.98 wt% within 5 minutes at ∼300°C) due to formation of intermediate compound Mg1−xTixO, and it retains nearly constant hydrogen storage capacity (from 5.25 to 5.20 wt% in rehydrogenation and from 4.95 wt % to 4.95 wt% in dehydrogenation) up to 60 cycles of de/re‐hydrogenation. The estimated desorption activation energy for MgH2‐TTIP using Arrhenius equation is 77.67 kJ/mol. The reason for de/re‐hydrogenation kinetics improvement of MgH2‐TTIP can be seen in the mechanism. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the efficacy of multiple combined procedure (Pentagon approach) as single-step secondary repair in cases of extensive keratolenticular trauma in paediatric age group. Methods: Retrospective evaluation of 18 patients of penetrating injuries with sclero-keratolenticular trauma, who underwent multiple procedure as single-step secondary repair by a single team of two surgeons during a 4 year period. Surgical procedure included reconstruction of anterior segment, synechiolysis, excision of membrane, lensectomy, open sky vitrectomy, PC IOL implantation over frill and penetrating keratoplasty. Meticulous antiamblyopia measures were applied in all cases. Results: Extensive vasoproliferative membrane, complicated cataract and anterior vitreous condensation were significant intra-operative hurdles. Moderate uveitis, secondary glaucoma, persistent epithelial defects were problems noted. Eleven (61.22%) patients attained good visual outcome. Regrafting was required in remaining cases due to delayed graft failure. Conclusion: Despite being a highly complex technique, Pentagon approach provides effective management profile in terms of graft success and functional outcome, especially in keratolenticular trauma, in children.