Ni-Activated Atomic Fe/Fe–Ni Heterosites for Decoupled C–N Coupling in Urea Electrosynthesis

The electrocatalytic co-reduction of nitrate (NO 3 − ) and carbon dioxide (CO 2 ) into urea represents a potential avenue for achieving efficient urea production. However, this process involves intricate C–N coupling reactions and faces a severe kinetic mismatch between the reduction pathways. This disparity typically leads to a disproportionate coverage of key C- and N-containing intermediates on the catalyst surface, resulting in dominant competitive side reactions. Herein, we report the design of a heterogeneous FeNi@AC catalyst that integrates isolated Fe single atoms and Fe–Ni dual-atom sites at the atomic scale, enabling the efficient conversion of NO 3 − and CO 2 into urea. Combined experimental and theoretical investigations reveal that the isolated Fe single-atom sites retain high nitrate reduction capability. Crucially, the introduction of Ni induces an electronic reconfiguration of the Fe center, which significantly lowers the energy barrier for CO 2 activation (from 0.7 eV to 0.1 eV). This activation effectively bridges the kinetic gap between C- and N-species. Consequently, the FeNi@AC catalyst achieves a urea yield rate of 13.6 mmol g –1 h –1 and a Faradaic efficiency of 51.7% at –0.8 V (vs RHE). This work not only presents an active catalyst for urea synthesis but also provides a site-specific regulation strategy for designing multifunctional atomic-site catalysts tailored for complex tandem reactions.