Modulating Co–Re Pairs in CoRe Alloy for Efficient NH₃ Synthesis under Mild Conditions

The development of advanced nonprecious-metal catalysts for efficient ammonia (NH 3 ) synthesis under mild conditions represents significant importance. However, the incompatibility between facile N 2 activation and NH 3 desorption in monometallic catalysts limits their catalytic activity for NH 3 synthesis. Herein, we systematically fabricated CoRe x alloy ( x = 0.25, 0.5, 0.75, 1, 1.5, and 2) catalysts by modulating the Co/Re ratio to achieve efficient NH 3 synthesis. Our studies reveal that the Co/Re ratio in CoRe x catalysts critically governs the formation of Co–Re paired sites, with the quantity of these pairs demonstrating a strong positive correlation with the NH 3 synthesis rates. Excess Co (CoRe 0.5 ) or Re (CoRe 2 ) leads to either insufficient N 2 activation or excessively strong NH 3 adsorption, both detrimental to catalytic efficiency. In contrast, the CoRe 1 alloy featuring abundant Co–Re pairs simultaneously realizes the facile N 2 activation and NH 3 desorption through a synergistic effect of Co–Re orbital hybridization. Consequently, the optimized CoRe 1 delivers a remarkable NH 3 synthesis rate of 12.0 mmol g cat –1 h –1 at 400 °C and 1 MPa, surpassing those of most reported NPM catalysts to date.