MnO Interface-Induced Ni Electronic Reconfiguration for Hydrogen-Activated Heterolysis and Enhanced Catalytic Hydrogenation of N-Ethylcarbazole

The facile catalytic hydrogenation of a liquid organic hydrogen storage carrier using a highly active, selective, and stable catalyst holds excellent potential for large-scale hydrogen energy applications. Herein, we design and synthesize a noble-metal free Ni4–MnO/Al2O3 catalyst with ultrasmall (3.04 nm) and stable Ni nanoparticles, which enables a highly efficient catalytic hydrogenation of N-ethylcarbazole (NEC). Notably, the Ni4–MnO/Al2O3 catalyst exhibits superior catalytic performance compared to those of the pure Ni catalyst and some state-of-the-art noble metal catalysts. Especially, its H2 uptake efficiency is over 52 times and 16 times higher than the previously reported LaNi5.5 and Raney Ni. The outstanding catalytic performance of the Ni4–MnO/Al2O3 catalyst is due to the optimal electronic structure and the expose of more electron-deficient Niδ+ active sites induced by the strong electronic coupling interaction between the electron-deficient Niδ+ and MnO species, which allows rapid interfacial electron transfer, leading to the optimal adsorption energy, reaction energy, and kinetics data. The probable mechanism of MnO-induced Ni-catalyzed NEC hydrogenation was thoroughly investigated and discussed by experimental analyses and density functional theory calculations.