Multi-site intermetallic Ni3Mo effectively boosts selective ammonia synthesis

Abstract

Carbon-free electrocatalytic nitrogen reduction reaction (NRR) offers an environmentally sustainable alternative to the current Haber-Bosch process in the industry. However, this process is still limited by the scaling relations and the competitive hydrogen evolution reaction (HER). Using the density functional theory, we theoretically present a strategy for separating the active sites of the N2 activation and the hydrogenation of NHz (z = 1, 2) intermediates on the Ni3Mo surface, which subtly optimized the adsorption of intermediates and bypasses the scaling relations, achieving efficient NRR with an ultralow limiting potential of − 0.19 V. Besides, the Ni3Mo greatly protects the active centers of NRR from competitive H adsorption and retard the undesired HER, enabling highly selective NH3 synthesis. The above theoretical designs are supported by proof-of-concept experimental results, where Ni3Mo exhibits excellent NRR performance with the NH3 yield rate of 17.35 ± 0.3 μg h−1 cm−2 at − 0.35 V.