Enhancing hydrogen storage performance of magnesium hydride with Ni cluster‐loaded MXene‐Nb ₂ CT _<i>x</i> (T _<i>x</i>  = F, O)

Abstract

Abstract The robust Mg‐H bonds present in magnesium hydride (MgH 2 ) hinder the dissociation of hydrogen molecules on MgH 2 , leading to suboptimal thermo dynamic and kinetic properties. Transition metals such as nickel (Ni) and Nb exhibit superior hydrogen absorption energies as compared to Mg. By integrating two‐dimensional Nb n C n‐ 1 T x ‐MXene (with a large specific surface area and strong hydrogen absorption capacity provided by Nb) with Ni clusters, we developed an effective catalyst for hydrogen adsorption in MgH 2 . This study focused on the synthesis of an efficient MXene‐Nb 2 CT x composite containing nano Ni cluster to enhance the hydrogenation and dehydrogenation processes of the Mg/MgH 2 system. The T x end groups (–F, –O) were found to interact with Ni to create Ni‐F or Ni–O bonds, which subsequently engage with adjacent Ni atoms to form Ni–Ni bonds. This interaction facilitates the loading of Ni clusters onto Nb 2 CT x and mitigates the inhibitory effects of –F or –O on hydrogen adsorption and desorption in the Mg‐based system. Consequently, Nb 2 C and Ni operate synergistically to enhance hydrogen dissociation and weaken Mg‐H bonds. Theoretical simulations revealed that the inclusion of the Nb 2 C/Ni catalyst in an elongation of Mg‐H bonds enhance hydrogen dissociation and weaken Mg‐H bonds. Theoretical simulations revealed that the inclusion of the Nb 2 C/Ni catalyst in an elongation of Mg‐H bonds facilitate hydrogen molecule dissociation on the Nb 2 C/Ni composite. Hydrogen storage performance assesments demonstrated that the Nb 2 C/Ni catalyst efficiently catalyzed hydrogen absorption and desorption; specifically, the hydrogenation/dehydrogenation capacity of Nb 2 C/Ni@MgH 2 reachedca. 5.0 wt% at 100 °C, while at 200 °C, the capacities for hydrogenation and dehydrogenation reached 7.0 wt% and 6.0 wt%, respectively, within 6 min.

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