Promising prospects of transition metal (Ti, Ni, Zr and Nb)-modified V₂C MXenes for improving the hydrogen storage performance of magnesium hydride

The effect of modifying V₂C using transition metals (TMs) (Ti, Ni, Zr, and Nb) on the MgH₂ dehydrogenation properties was investigated using the density functional theory (DFT). The adsorption energy, dehydrogenation energy, and electronic structure of MgH₂ on TM (Ti, Ni, Zr, and Nb)@V₂C were calculated. The results showed that TM atoms tended to occupy the face-centered cubic sites of V₂C. MgH₂ adsorption on V₂C was improved by adding a TM and the order of the adsorption energy was as follows: Ni@V₂C > Ti@V₂C > Zr@V₂C > Nb@V₂C > V₂C. An orbital hybridization peak between H and TM atoms was observed in the electronic structure of MgH₂ on TM (Ti, Ni, Zr, and Nb)@V₂C. The addition of a TM supported on V₂C substantially improved the dehydrogenation energy of (MgH₂)₄ clusters, and the order of improvement was Ni@V₂C > Ti@V₂C > Nb@V₂C > Zr@V₂C. The dehydrogenation energy of (MgH₂)₄ clusters on Ni@V₂C was lower than that of pure (MgH₂)₄ clusters and (MgH₂)₄ clusters on V₂C, by 1.60 and 1.11 eV, respectively. TM@V₂C combinations had significantly enhanced MgH₂ dehydrogenation, providing theoretical justification for conducting experiments to develop novel high-performance catalysts.