Promoting Electroreduction of CO<sub>2</sub> and NO<sub>3</sub><sup>−</sup> to Urea via Tandem Catalysis of Zn Single Atoms and In<sub>2</sub>O<sub>3‐x</sub>
Ying Zhang, Zhuohang Li, Kai Chen, Xing Yang, Hu Zhang, Xijun Liu, Ke Chu
Abstract
Abstract Urea electrosynthesis from co‐electrolysis of CO 2 and NO 3 − (UECN) offers an innovative route for converting waste CO 2 /NO 3 − into valuable urea. Herein, Zn single atoms anchored on oxygen vacancy (OV)‐rich In 2 O 3‐x (Zn 1 /In 2 O 3‐x ) are developed as a highly active and selective UECN catalyst, delivering the highest urea yield rate of 41.6 mmol h −1 g −1 and urea‐Faradaic efficiency of 55.8% at −0.7 V in flow cell, superior to most previously reported UECN catalysts. In situ spectroscopic measurements and theoretical calculations unveil the synergy of In/Zn 1 sites and OVs in promoting the UECN process via a tandem catalysis mechanism, where Zn 1 ‐OV site activates NO 3 − to form * NH 2 while In‐OV site activates CO 2 to form * CO. The formed * CO spontaneously migrates from the In‐OV site to the nearby Zn 1 ‐OV site and then couples with * NH 2 to generate * CONH 2 which is ultimately converted into urea.