Traditional urea synthesis is energy-intensive and has a high carbon footprint, making the direct electrocatalytic synthesis from CO2 and NO3− under mild conditions highly attractive. However, designing efficient bimetallic catalysts that promote C–N coupling while suppressing side reactions remains a key challenge. This study reports a metal ionic liquid-mediated pyrolysis strategy for constructing carbon nanofibers embedded with highly dispersed Ru–Cu bimetallic nanoparticles (Ru/Cu@CF). A self-synthesized salicylic acid-imidazole metal ionic liquid served as a trifunctional precursor, enabling 10 nm level dispersion and stable anchoring of the metals within the carbon matrix after programmed carbonization. The resulting Ru/Cu@CF features a 3D porous fibrous structure, high surface area, abundant defects, and amorphous/highly dispersed Ru–Cu species. For electrocatalytic co-reduction of CO2 and NO3− to urea, Ru/Cu@CF achieved a high urea yield of 57.8 mmol g−1 h−1 and a Faradaic efficiency of 25.4% at a mild potential of −0.5 V vs. RHE, along with good stability. Comparative studies confirmed the crucial role of Ru–Cu synergy in enhancing activity and selectivity.
Chang et al. (2026) studied this question.