Electrochemical Co-reduction of N₂ and CO₂ to Urea Using Bi₂S₃ Nanorods Anchored to N-Doped Reduced Graphene Oxide

Producing “green urea” using renewable energy, N 2, and CO 2 is a long-considered challenge. Herein, an electrocatalyst, Bi 2 S 3 /N-reduced graphene oxide (RGO), was synthesized by loading the Bi 2 S 3 nanorods onto the N-RGO via a hydrothermal method. The Bi 2 S 3 /N-RGO composites exhibit the highest yield of urea (4.4 mmol g –1 h –1 ), which is 12.6 and 3.1 times higher than that of Bi 2 S 3 (0.35 mmol g –1 h –1 ) and that of N-RGO (1.4 mmol g –1 h –1 ), respectively. N-RGO, because of its porous and open-layer structure, improves the mass transfer efficiency and stability, while the basic groups (-OH and -NH 2 ) promote the adsorption and activation of CO 2 . Bi 2 S 3 promotes the absorption and activation of inert N 2 . Finally, the defect sites and the synergistic effect on the Bi 2 S 3 /N-RGO composites work simultaneously to form urea from N 2 and CO 2 . This study provides new insights into urea synthesis under ambient conditions and a strategy for the design and development of a new material for green urea synthesis.