Promoting the Intermediates Hydrogenation for Urea Electrosynthesis Over an "Active Hydrogen Pump" Catalyst

Electrocatalytic coupling of CO₂ and NO₃ ^- offers a sustainable approach for urea production. However, the limited supply of active hydrogen (*H) hinders the formation of the key carbon- and nitrogen-containing intermediates, thus impeding the selective C─N coupling. Herein, we developed copper molybdate (Cu₃Mo₂O₉) nanorods, which could serve as "active hydrogen pump" catalysts by regulating the water dissociation and hydrogen adsorption. Such electrocatalyst would guarantee a steady *H supply for intermediates hydrogenation, hence boosting the generation of *CO and *NH₂ intermediates for selective C‒N coupling and urea production. In a CO₂-saturated 0.1 M KNO₃ solution, Cu₃Mo₂O₉ achieved a maximum urea yield rate of 177 mmol h^-1 g^-1 with a urea-producing FE of 40% in a flow cell configuration, outperforming most reported electrocatalysts. This study underscores the crucial role of *H, which may guide the exploration of advanced catalysts for expediting the sustainable synthesis of indispensable chemicals requiring rapid intermediates hydrogenation.