A High-Performance Bimetallic Ru₁Mo₆ Active Site for Thermal Ammonia Synthesis under Mild Conditions

Ammonia (NH₃) synthesis is among the greatest discoveries in human history. While dinitrogen (N₂) is converted in nature under ambient conditions to NH₃ through an associative mechanism at the FeMoco active site of nitrogenase, the industrialized Haber-Bosch process involves an N₂ dissociative mechanism on the C₇ site of iron or the B₅ site of ruthenium, which requires harsh conditions of high temperatures (430-500 °C) and high pressures (10-30 MPa). Here, we report a new active site of Ru₁Mo₆ bimetallic single-cluster anchored on Mo₂CT_x MXene for efficient NH₃ synthesis. This highly stable catalyst can achieve N₂-to-NH₃ thermal synthesis under mild conditions (T = 50 °C and P = 0.1 MPa). An exceptionally high NH₃ production rate of 3230 mmol g_Ru^-1 h^-1 with >1000 h of long-term stability has been achieved at 400 °C and 1 MPa, which is roughly three times higher than those of highly dispersed Ru catalysts ever reported. This new catalyst featuring an atomically precise single-cluster active site holds promise for designing robust catalytic systems for N₂-to-NH₃ thermal conversion under mild conditions.