Kinetically matched C–N coupling toward efficient urea electrosynthesis enabled on copper single-atom alloy

Abstract

Chemical C–N coupling from CO 2 and NO 3–, driven by renewable electricity, toward urea synthesis is an appealing alternative for Bosch–Meiser urea production. However, the unmatched kinetics in CO 2 and NO 3– reduction reactions and the complexity of C- and N-species involved in the co-reduction render the challenge of C–N coupling, leading to the low urea yield rate and Faradaic efficiency. Here, we report a single-atom copper-alloyed Pd catalyst (Pd 4 Cu 1) that can achieve highly efficient C–N coupling toward urea electrosynthesis. The reduction kinetics of CO 2 and NO 3– is regulated and matched by steering Cu doping level and Pd 4 Cu 1/FeNi(OH)2 interface. Charge-polarized Pd δ–-Cu δ+ dual-sites stabilize the key *CO and *NH 2 intermediates to promote C–N coupling. The synthesized Pd 4 Cu 1-FeNi(OH)2 composite catalyst achieves a urea yield rate of 436.9 mmol g cat.–1 h–1 and Faradaic efficiency of 66.4%, as well as a long cycling stability of 1000 h. In-situ spectroscopic results and theoretical calculation reveal that atomically dispersed Cu in Pd lattice promotes the deep reduction of NO 3– to *NH 2, and the Pd-Cu dual-sites lower the energy barrier of the pivotal C–N coupling between *NH 2 and *CO.