Ternary intermetallic LaCoSi as a catalyst for N₂ activation

Activating high-energy multiple bonds using earth-abundant metals is one of the most significant challenges in catalysis. Here, we show that LaCoSi - a ternary intermetallic compound - is an efficient and stable catalyst for N₂ activation to produce NH₃. The ammonia synthesis is significantly promoted by shifting the reaction bottleneck from the sluggish N₂ dissociation to NH _x formation, which few catalysts have achieved. Theoretical calculations reveal that the negatively charged cobalt mediates electron transfer from lanthanum to the adsorbed N₂, which further reduces the activation barrier of N₂ dissociation. Most importantly, the specific LaCoSi geometric configuration stabilizes the N₂ adsorption with a strong exothermic effect, which dramatically decreases the apparent energy barrier of N₂ activation. Consequently, LaCoSi shows a superior activity (1,250 μmol g^-1 h^-1), with a 60-fold increase over the activity of supported cobalt catalysts under mild reaction conditions (400 °C, 0.1 MPa).