Ru-Loaded C12A7:e– Electride as a Catalyst for Ammonia Synthesis

The artificial mass production of ammonia has supported the increase in human population and modern civilization for over 100 years. However, more efficient ammonia production is now a significant concern for society. Here we show that Ru-loaded C12A7:e– electride derived from 12CaO·7Al2O3 (C12A7:O2–) acts as an efficient and stable catalyst for ammonia synthesis. Ammonia synthesis over Ru nanoparticles-loaded C12A7:e– (Ru/C12A7:e–) is distinct from other conventional catalysts in both mechanism and properties. The dissociative adsorption of N2 molecules, which is the largest energy barrier in ammonia synthesis for conventional catalysts, is no longer the rate-limiting step for the Ru/C12A7:e– catalyst. In addition, Ru on the electride prevents the inhibition of ammonia synthesis by hydrogen adatoms, known as hydrogen poisoning, which is a common and serious drawback of Ru catalysts. This characteristic results in the highly efficient formation of ammonia over the Ru/C12A7:e– catalyst.