Boosting Up Electrosynthesis of Urea with Nitrate and Carbon Dioxide via Synergistic Effect of Metallic Iron Cluster and Single-Atom

Abstract

Electrocatalytic conversion of nitrates and carbon dioxide to urea under ambient conditions shows promise as a potential substitute for traditional urea synthesis processes characterized by high consumption and pollution. In this study, a straightforward one-pot method is employed to prepare a highly efficient FeNC-Fe₁N₄ electrocatalyst, consisting of atomically dispersed Fe₁N₄ sites and metallic Fe clusters (FeNC) with particle size of 4–7 nm. The FeNC-Fe₁N₄ catalyst exhibits remarkable electrocatalytic activity for urea synthesis from nitrate anion (NO₃⁻) and carbon dioxide (CO₂), achieving a urea production rate of 38.2 mmol g_cat⁻¹ h⁻¹ at −0.9 V (vs RHE) and a Faradaic efficiency of 66.5% at −0.6 V (vs RHE). Both experimental and theoretical results conclusively demonstrate that metallic Fe clusters and Fe₁N₄ species provide active sites for the adsorption and activation of NO₃⁻ and CO₂, respectively, and the synergistic effect between Fe₁N₄ and metallic Fe clusters significantly enhances the electrochemical efficiency of urea synthesis. In all, this work contributes to the rational design and comprehensive synthesis of a dual-active site iron-based electrocatalyst, facilitating efficient and sustainable urea synthesis.