Porous core–shell CuAu@Cu2O catalyst for acidic C–N coupling toward urea electrosynthesis from CO2 and nitrate

Abstract

Traditional neutral/alkaline systems face limitations due to incompatibility with acidic industrial wastewater and spontaneous carbonate byproduct formation, causing reactant depletion and low efficiency. While acidic conditions enhance industrial applicability, challenges persist: insufficient adsorption energy for key intermediates, hydrogen evolution reaction (HER) competition, and catalyst corrosion. This study developed a porous core–shell CuAu@Cu₂O catalyst, achieving 55.4% faradaic efficiency and 1824.8 μg h⁻¹ mg⁻¹ urea yield at −0.5 V vs. RHE in acidic media, with 100-hour stability. Mechanistic insights reveal that Cu/Au dual sites synergistically activate CO₂ and NO₃⁻, lowering *COOH/*NOH intermediate adsorption energies; the Cu₂O shell regulates proton supply via Au-mediated electronic effects, promoting C–N coupling while suppressing the HER; and charge redistribution from Cu to Au at the porous interface stabilizes the catalyst structure. This work not only provides an efficient catalyst for urea electrosynthesis under acidic conditions, but also pioneers a novel ‘waste-treating-waste’ green synthesis paradigm, offering new insights for electrochemical manufacturing in the context of carbon neutrality goals.