Synergistic nanoconfinement-catalytic effect in Mg(BH4)2–TiNbNiCuO@GR high-entropy system: Boosted dehydrogenation kinetics and reversibility

Developing a strategy for efficiently synthesizing borohydrides with high capacity and favorable reversibility is significant for promoting the development of next-generation energy materials. This work proposes a novel Mg(BH 4 ) 2 –TiNbNiCuO@graphene (Mg(BH 4 ) 2 –TiNbNiCuO@GR) high-entropy system, integrating nanoconfinement and catalytic strategies to significantly enhance the dehydrogenation kinetics and cycling stability of Mg(BH 4 ) 2 . TiNbNiCuO medium-entropy oxide (MEO) were synthesized in situ on a graphene carbon skeleton as catalyst (TiNbNiCuO@GR). Subsequently, Mg(BH 4 ) 2 was slowly infiltrated into the TiNbNiCuO@GR framework, which served as a carrier for nanoconfined Mg(BH 4 ) 2 , forming the Mg(BH 4 ) 2 –TiNbNiCuO@GR. It is demonstrated that the close contact between nanoconfined TiNbNiCuO MEO and Mg(BH 4 ) 2 creates abundant active sites, which facilitates electron transfer to improve dehydrogenation kinetics (dehydrogenation onset temperature at 63.5 °C) with a high capacity of 9.8 wt% H 2 . Notably, high-entropy effect and nanoconfinement boost the structure stability of TiNbNiCuO and prevent the agglomeration of Mg(BH 4 ) 2 , respectively, thereby jointly achieving an enhanced reversibility of the dehydrogenation kinetics, enabling a capacity retention of 81.5% after 10 cycles. The synergistic nanoconfinement-catalytic effect within the Mg(BH 4 ) 2 –TiNbNiCuO@GR offers new insights into the efficient dehydrogenation pathway of Mg-based borohydride systems. • A novel Mg(BH 4 ) 2 –TiNbNiCuO@GR high-entropy system was proposed. • Excellent hydrogen storage with low-temperature and fast dehydrogenation. • Outstanding reversibility and structural stability during hydrogen cycling. • Synergistic nanoconfinement and catalysis effect.