Lattice Oxygen-Driven Co-Adsorption of Carbon Dioxide and Nitrate on Copper: A Pathway to Efficient Urea Electrosynthesis
Xiaoxiao Wei, Shaoqing Liu, Hengjie Liu, Yutian Ding, Peng‐Xia Lei, Shuwen Wu, Li Song, Xian‐Zhu Fu, Jing‐Li Luo
Abstract
The electrochemical coupling of CO 2 and NO 3 – on copper-based catalysts presents a sustainable strategy for urea production while simultaneously addressing wastewater denitrification. However, the inefficient random adsorption of CO 2 and NO 3 – on the copper surface limits the interaction of the key carbon and nitrogen intermediates, thereby impeding efficient C–N coupling. In this study, we demonstrate that the residual lattice oxygen in oxide-derived copper nanosheets (O L -Cu) can effectively tune the electron distribution, thus activating neighboring copper atoms and generating electron-deficient copper (Cu δ+ ) sites. These Cu δ+ sites enhance CO 2 adsorption and stabilize *CO intermediates, which enables the directional NO 3 – adsorption at adjacent Cu δ+ sites. This mechanism shortens the C–N coupling pathway and achieves a urea yield of up to 298.67 mmol h –1 g –1 at −0.7 V versus RHE, with an average Faradaic efficiency of 31.71% at a high current density of ∼95 mA cm –2 . In situ spectroscopic measurements confirmed the formation of Cu δ+ sites and tracked the evolution of the key intermediates (i.e., *CO, *NO, *OCNO, and *NOCONO) during urea synthesis. Density functional theory calculations revealed that Cu δ+ sites promote adjacent coadsorption of *CO and *NO 3, as well as *OCNO and *NO 3, significantly improving C–N coupling kinetics. This study underscores the critical role of lattice oxygen in facilitating adjacent coadsorption and improving C–N coupling selectivity.