Efficient Ammonia Synthesis on Electride-Supported Single-Atom Sc Catalysts through Electron-Buffered N2 Activation and Subsurface-Hydrogen-Assisted Hydrogenation.

Ammonia synthesis is a crucial industrial process for sustainable human development. Electrides, with their unique electron-donating capability, have shown great promise in overcoming the fundamental challenge of activating the inert NN bond. To harness this potential, we propose a single-Sc-atom-anchored LaNiSi electride as a stable, sinter-resistant, and highly active catalyst for ammonia synthesis. Computational simulations reveal that substantial electron transfer from the electride support, exclusively effective at the Sc site, drives efficient N2 activation and dissociation. Unlike conventional electride catalysts, the Sc site not only cleaves N2 but also mediates all subsequent hydrogenation steps, exhibiting a distinctive "one-stop" catalytic mechanism. We further identify the coexistence of surface and subsurface hydrogen species, with hydrogenation dominated by the latter through a previously overlooked pathway that is both thermodynamically and kinetically favorable. Energy span analysis confirms that the overall catalytic efficiency of this route is comparable to that of benchmark Ru catalysts. This work not only presents a stable and highly active single-atom catalyst but also elucidates a unique reaction mechanism on electride surfaces, offering a novel design strategy for advanced ammonia synthesis catalysts.