Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH₂. Herein, the sulfur doped Ti₃C₂ (S-Ti₃C₂) was successfully prepared by heat treatment of Ti₃C₂ MXene under Ar/H₂S atmosphere to facilitate the hydrogen release and uptake from MgH₂. The S-Ti₃C₂ exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH₂. The addition of 5 wt% S-Ti₃C₂ into MgH₂ resulted in a reduction of 114 ℃ in the starting dehydriding temperature compared to pure MgH₂. MgH₂ + 5 wt% S-Ti₃C₂ sample could quickly release 6.6 wt% hydrogen in 17 min at 220 ℃, and 6.8 wt% H₂ was absorbed in 25 min at 200 ℃. Cyclic testing revealed that MgH₂ + 5 wt% S-Ti₃C₂ system achieved a reversible hydrogen capacity of 6.5 wt%. Characterization analysis demonstrated that Ti-species (Ti⁰, Ti²⁺, Ti–S, and Ti³⁺) as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH₂, and sulfur doping can effectively improve the stability of Ti⁰ and Ti³⁺, contributing to the improvement of cyclic stability of MgH₂. This study provides strategy for the construction of catalysts for hydrogen storage materials.

Magnesium hydride (MgH₂) is considered as an ideal hydrogen storage material with excellent hydrogen capacity, but the slow kinetics impedes its application. Herein, an efficient additive of V₂C MXene-anchored PrF₃ nanoparticles (PrF₃/V₂C) was synthesized, which presents excellent catalytic effect in improving the reversibility and stability of hydrogen storage in MgH₂. The initial dehydrogenation temperature of the 5 wt.% PrF₃/V₂C-containing MgH₂ (182 °C) is 105 °C lower than that of pure MgH₂, and 6.5 wt.% hydrogen is rapidly released from 5 wt.% PrF₃/V₂C-added MgH₂ sample in 6 min at 240 °C. In addition, 5 wt.% PrF₃/V₂C-containing MgH₂ sample possesses outstanding reversible hydrogen storage capability of 6.5 wt.% after 10 cycles of dehydrogenation and hydrogenation. Microstructure analysis shows that the introduction of Pr improves the stability of V-species (V⁰ and V²⁺) and O-species (lattice oxygen (O_L) and vacancy oxygen (O_V)) formed during ball milling, promotes the interaction between V-species and O-species, and enhances their reversibility, which contributes to the significant improvement in re/dehydrogenation reversibility and cycling stability of MgH₂. This study provides effective ideas and strategies for the purpose of designing and fabricating high-efficient catalysts for solid-state hydrogen storage materials.

Boron hydrides release an abundant amount of hydrogen in the presence of a suitable catalyst. Accelerating bimolecular activation kinetics is the key to designing cost-effective catalysts for borohydride hydrolysis. In this study, the bimolecular activation of a polar O–Co–P site demonstrated superior hydrogen-generation kinetics (turnover frequency, TOF = 37 min⁻¹, 298 K) and low activation energy (41.0 kJ mol⁻¹) close to that of noble-metal-based catalysts. Through a combination of experiments and theoretical calculations, it was revealed that the activated dangling oxygen atom in the Co–O precursor effectively replaced via surface-phosphorization because of strong electronic interactions between the dangling oxygen and P atoms. This substitution modulated the local coordination environment and electronegativity around the surface Co sites and formed a new polar O–Co–P active site for optimizing the activation kinetics of ammonia borane and water. This strategy based on bimolecular activation may create new avenues in the field of catalysis.