Tuning Intermediates Adsorption and C─N Coupling for Efficient Urea Electrosynthesis Via Doping Ni into Cu

Abstract

Simultaneous electrochemical reduction of nitrite and carbon dioxide (CO₂ ) under mild reaction conditions offers a new sustainable and low-cost approach for urea synthesis. However, the development of urea electrosynthesis thus far still suffers from low selectivity due to the high energy barrier of ^* CO formation and the subsequent C─N coupling. In this work, a highly active dendritic Cu₉₉ Ni₁ catalyst is developed to enable the highly selective electrosynthesis of urea from co-reduction of nitrite and CO₂ , reaching a urea Faradaic efficiency (FE) and production rate of 39.8% and 655.4 µg h^-1 cm^-2 , respectively, at -0.7 V versus reversible hydrogen electrode (RHE). In situ Fourier-transform infrared spectroscopy (FT-IR) measurements together with density functional theory (DFT) calculations demonstrate that Ni doping into Cu can significantly enhance the adsorption energetics of the key reaction intermediates and facilitate the C─N coupling. This work not only provides a new strategy to design efficient electrocatalysts for urea synthesis but also offers deep insights into the mechanism of C─N coupling during the co-reduction of nitrite and CO₂ .

Keywords: CO2 reduction; C─N coupling; Ni doping; nitrite reduction; urea synthesis.