In this work, we report the remarkable catalytic effects of a novel Ti3C2 MXene-based catalyst (Ni@Ti-MX), which was prepared via self-assembling of Ni nanoparticles onto the surface of exfoliated Ti3C2 nanosheets. The resultant Ni@Ti-MX catalyst, characterized by ultradispersed Ni nanoparticles being anchored on the monolayer Ti3C2 flakes, was introduced into MgH2 through ball milling. In situ transmission electron microscopy (TEM) analysis revealed that a synergetic catalytic effect of multiphase components (Mg2Ni, TiO2, metallic Ti, etc.) derived in the MgH2 + Ni@Ti-MX composite exhibits remarkable improvements in the hydrogen sorption kinetics of MgH2. In particular, the MgH2 + Ni@Ti-MX composite can absorb 5.4 wt % H2 in 25 s at 125 °C and release 5.2 wt % H2 in 15 min at 250 °C. Interestingly, it can uptake 4 wt % H2 in 5 h even at room temperature. Furthermore, the dehydrogenation peak temperature of the MgH2 + Ni@Ti-MX composite is about 221 °C, which is 50 and 122 °C lower than that of MgH2 + Ti-MX and MgH2, respectively. The excellent hydrogen sorption properties of the MgH2 + Ni@Ti-MX composite are primarily attributed to the peculiar core–shell nanostructured MgH2@Mg2NiH4 hybrid materials and the interfacial coupling effects from different catalyst–matrix interfaces. The results obtained in this study demonstrate that using self-assembling of transition-metal elements on two-dimensional (2D) materials as a catalyst is a promising approach to enhance the hydrogen storage properties of MgH2.

Developing high capacity, rechargeable magnesium batteries is highly desired to meet increasing energy demands while targeting viable replacements for lithium batteries.

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