Single-Atom Cu Supported on Ti₃C₂Tx for Catalyzing Hydrogen Storage in MgH₂

Magnesium hydride (MgH 2 ) has been considered a promising hydrogen storage material, but its commercial application is severely limited by high operating temperature and slow de/hydrogenation kinetics. Herein, an efficient catalyst, Cu SA /Ti 3 C 2 T x, is successfully synthesized by introducing a Cu single-atom into Ti 3 C 2 T x MXene nanosheets and applied to MgH 2 . The synthesized MgH 2 + 5 wt %Cu SA /Ti 3 C 2 T x (Cu SA /Ti 3 C 2 T x /MgH 2 ) composite exhibits low initial dehydrogenation temperature ( T = 241.73 °C) and rapidly dehydrogenation kinetics ( E a = 76.38 kJ/mol H 2 ). Impressively, the Cu SA /Ti 3 C 2 T x /MgH 2 composite desorbs 3.3 wt % of hydrogen within 240 min at 180 °C after 20 cycles, as well as an initial dehydrogenation temperature of 164.29 °C. The superior catalytic effect of Cu SA /Ti 3 C 2 T x catalyst is ascribed to the numerous catalytic active area, in-situ-formed active metallic Ti, and multivalent Ti species, accelerating the electron transfer and weakening the strength of Mg–H bonds. In particular, the Cu single-atom improved the stability of Ti 4+ in Ti 3 C 2 T x, thereby enhancing its catalytic ability. This work provides a new perspective for ameliorating the catalytic ability of MXene.