Simultaneously Nanoconfining Mg and Loading Multiple Metal Single Atoms Catalysts with N-Doped Carbon to Achieve Room-Temperature Dehydrogenation.

Abstract

Nanoconfinement and single-atom catalysis are effective strategies for improving the hydrogen storage performance of Mg. However, achieving high loading nanoconfinement Mg and introducing multiple metal single atoms catalysts simultaneously is extremely challenging. This work developed a novel metal cation doping - thermal decomposition strategy to successfully prepare Mg-SAs@C nanocomposites with multiple metal single atoms (SAs) embedded in a MOF-derived-nitrogen-doped carbon scaffold. The Mg-(NiCoFeTi-SAs)@C nanocomposite has fine Mg nanoparticles of 7.4 nm and a high loading rate of 72.4%. Surprisingly, Mg-(NiCoFeTi-SAs)@C begins to dehydrogenate at room-temperature with a saturation capacity of 5.3 wt.%. In particular, the hydrogen release kinetics and thermodynamic performance are significantly improved (Ea(des) = 48.5 kJ mol-1 H2, ΔHdes = 59.6 kJ mol-1 H2). Attributed to the synergistic effect between multiple single atoms and N, as well as the carbon scaffold, the electron transfer efficiency is increased, resulting in a significantly higher charge transfer amount for Mg-(NiCoFeTi-SAs)@C (1.88 eV) compared to Mg-(Ni-SAs)@C (0.06 eV) with only one single-atom added. This work has opened a new path for introducing multiple single-atom catalysts into Mg-based materials, and also provided new insights into exploring the catalytic mechanism of multiple metal single-atom catalysts.