Phosphorus-Doped Cu/Fe₂O₃ Electrocatalysts with Optimized Synergy between the Different Sites for Efficient Urea Electrosynthesis

Urea electrosynthesis from the coelectrolysis of CO₂ and NO₃^- (UECN) has emerged as a promising sustainable alternative to traditional energy-intensive methods; however, the rational design of advanced electrocatalysts capable of achieving concurrent optimization of Faradaic efficiency (FE) and urea yield rates continues to pose a fundamental challenge in this field. Herein, we developed a phosphorus-doped Cu/Fe₂O₃ electrocatalyst (denoted as P-Cu/Fe₂O₃), where phosphorus atoms partially substitute for oxygen atoms within the Cu/Fe₂O₃ heterostructure. This engineered electrocatalyst achieves exceptional urea electrosynthesis performance, delivering a very high Faradaic efficiency of 73.81% with a corresponding yield rate of 62.74 mmol h^-1 g^-1_cat. at -0.68 V vs RHE, which are superior to most UECN electrocatalysts reported to date. Notably, the urea yield rate can be further boosted to 97.11 mmol h^-1 g^-1_cat. at -0.88 V vs RHE. Operando spectroscopic characterization and density functional theory (DFT) simulations indicated that P doping modulates the electronic structure of the electrocatalyst surface, which promotes the formation of *CO and *NO, lowers the energy barrier for the coupling of *CO and *NO, and increases *H coverage to facilitate the hydrogenation process during UECN. This multisite cooperative mechanism establishes a new paradigm for designing high-performance electrocatalysts, demonstrating substantial potential for industrial-scale urea production.