Synergistic coupling of carbon dioxide and nitrate for efficient electrosynthesis of urea using Cu-doped CeO2 nanorods

The electrocatalytic co-reduction of carbon dioxide (CO₂) and nitrate (NO₃⁻) to urea represents a sustainable alternative to energy-intensive industrial synthesis processes. Herein, we report copper-doped cerium oxide nanorods (Cu-CeO₂) as an efficient catalyst for this reaction, achieving a urea yield of 358.5 mg·h⁻¹·g⁻¹ at −0.7 V vs. reversible hydrogen electrode with 21.1% Faradaic efficiency. In situ Fourier transform infrared spectroscopy analysis reveals that during electrocatalytic urea synthesis, CO₂ activation at the catalyst surface generates carbonyl-containing intermediates (*CO), which couple with nitrogenous species (NH_x) derived from NO₃⁻ reduction. The key coupling reaction intermediate *NHCO was detected, and the *NHCO intermediate played a crucial role in promoting C–N bond formation. The stability of this intermediate directly facilitated the successful formation of urea. These findings elucidate the reaction pathway mediated by the Cu-CeO₂ catalyst, establishing a theoretical foundation for subsequent catalyst design optimization.