Tuning intermediates' adsorption for efficient electrosynthesis of urea from carbon dioxide and nitrate via doping Au into Cu

Abstract

The electrochemical co-reduction of carbon dioxide (CO₂) and nitrate (NO₃⁻) to urea presents a sustainable strategy to alleviate the ecological and food crisis. However, the current urea electrosynthesis faces low selectivity issues due to the high energy barrier of C–N coupling, as well as the unbalanced supply of key intermediates. Herein, we report that a Au-doped Cu bimetallic catalyst effectively balances the supply of C-containing and N-containing intermediates, thereby enhancing urea selectivity. In situ Raman spectroscopy and density functional theory calculations demonstrate that doping Au into Cu enhances the surface coverage of the *CO intermediate and optimizes the adsorption energy of *NO, thereby lowering the energy barrier of C–N coupling from 0.44 eV on the Cu surface to 0.15 eV on the Cu–Au surface. Meanwhile, this doping engineering also suppresses the reactions competing with urea electrosynthesis. As a result, the Cu–Au catalyst achieves a urea faradaic efficiency of 67.81% and a yield rate of 49.34 μmol cm⁻² h⁻¹ at −0.4 V versus the reversible hydrogen electrode.