Realizing efficient C-N coupling via electrochemical co-reduction of CO2 and NO3- on AuPd nanoalloy to form urea: Key C-N coupling intermediates

Abstract

Electrochemical C-N coupling of carbon dioxide and oxynitride under ambient environment is an emerging approach which promisingly enables sustainable production of valuable industrial chemicals, such as amines and their derivatives. However, the understanding of the C-N coupling is still in its infancy. Herein, we reported highly efficient electrochemical co-reduction of carbon dioxide and nitrate to form urea catalyzed by AuPd nanoalloy. Faradic efficiency and urea formation rate achieved 15.6% and 204.2 μg·mg−1·h−1, respectively, in a gas-tight H-type cell under ambient environment. The DFT studies on the C-N coupling mechanism showed that hydroxylamine was the most likely C-N coupling N-intermediate among many nitrogen-containing intermediates and that *NH2OH and *CO, rather than *NH2 and *CO, were confirmed to realize the C-N coupling to form urea through a one-step synergistic coupling which is a thermodynamically spontaneous process with a low activation barrier. This work not only provides new insights into the C-N coupling of oxynitride and carbon dioxide under ambient environment, but also may pave a way for promoting sustainable production of C-N coupling products.