In-Situ Electrochemical Reconstruction of Copper Single-Sites to Dual-Sites for Ambient Urea Synthesis

Abstract

Understanding and uncovering really catalytic active-sites during electrocatalysis is vital for carbon–nitrogen coupling reaction to synthesize urea. Here, we report a Copper (Cu) single-atom catalyst (Cu-N₃ SAs) with a Cu–N₃ coordination structure for the electrochemical coreduction of CO₂ and NO₃⁻ into urea. The in situ X-ray absorption spectroscopy (XAS) reveals that the Cu–N₃ configured single-sites undergo electrochemically structural reconstruction to form N₂–Cu–Cu–N₂ dual-sites in Cu–N₃ SAs, exhibiting efficient urea synthesis performance. The in-situ spectroscopy combined with mass spectrometry confirms that the initial C–N coupling reaction involves the formation of *CONH from *CO and *NH intermediates generated via the coreduction of CO₂ and NO₃⁻ on the N₂–Cu–Cu–N₂ dual-sites. The in-situ electrochemical formed Cu dual-sites not only enhance the adsorption of *CO, but also facilitates the multi-electron transfer processes with lowered energy barrier for the formation of *CONH intermediates.