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

Magnesium hydride (MgH2) 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, CuSA/Ti3C2Tx, is successfully synthesized by introducing a Cu single-atom into Ti3C2Tx MXene nanosheets and applied to MgH2. The synthesized MgH2 + 5 wt %CuSA/Ti3C2Tx (CuSA/Ti3C2Tx/MgH2) composite exhibits low initial dehydrogenation temperature (T = 241.73 °C) and rapidly dehydrogenation kinetics (Ea = 76.38 kJ/mol H2). Impressively, the CuSA/Ti3C2Tx/MgH2 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 CuSA/Ti3C2Tx 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 Ti4+ in Ti3C2Tx, thereby enhancing its catalytic ability. This work provides a new perspective for ameliorating the catalytic ability of MXene.