Polymetallic Oxide Catalysts for Electrocatalytic Synthesis of Urea from N2 and CO2 at Ultralow Applied Voltage

Due to operation at ambient temperature and pressure, the electrocatalytic synthesis of urea from N 2 and CO 2 is promising. However, the high consumption of electrical energy reduces the interest of the industrial sector. Reducing the applied voltage for the electrocatalytic synthesis of urea is an urgent issue to be solved. Herein the polymetallic oxide FeCoNiCuMO x ( M = Ce, Mg, In, Zn) catalysts have been fabricated, and their catalytic performance for electrocatalytic urea synthesis has been investigated. Among those catalysts, the FeCoNiCuCeO x catalyst shows the highest activity and selectivity toward urea. At an ultralow applied voltage of −0.2 V (vs RHE), the formation rate of urea reaches 6.37 mmol g cat –1 h –1, with a corresponding Faradaic efficiency of 26.7%. The oxygen vacancy in FeCoNiCuCeO x plays a crucial role in enhancing the catalytic performance by facilitating the adsorption/activation of CO 2 and N 2 . The higher adsorption capacity and binding energy of CO 2 and N 2 lead to a higher electrocatalytic performance of FeCoNiCuCeO x . Higher C–N coupling efficiency originates from higher coverage of *CO and optimal binding strength between *CO and the catalyst surface. The synergy of CuFe 2 O 4 /CoNiO 2 and CeO 2 with an oxygen vacancy enhances the electrocatalytic performance of FeCoNiCuCeO x .