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

Abstract

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.

Graphical abstract

Keywords

CeO₂ / Cu doping / C–N coupling / electrosynthesis / urea

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Higher Education Press