Producing "green urea" using renewable energy, N2, and CO2 is a long-considered challenge. Herein, an electrocatalyst, Bi2S3/N-reduced graphene oxide (RGO), was synthesized by loading the Bi2S3 nanorods onto the N-RGO via a hydrothermal method. The Bi2S3/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 Bi2S3 (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 -NH2) promote the adsorption and activation of CO2. Bi2S3 promotes the absorption and activation of inert N2. Finally, the defect sites and the synergistic effect on the Bi2S3/N-RGO composites work simultaneously to form urea from N2 and CO2. 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.
Keywords: Bi2S3 nanorods; N-doped reduced graphene oxide; N2 and CO2 adsorption and activation; couple C−N bond; electrocatalytic synthesis of urea.