Promoting Electroreduction of CO2 and NO3− to Urea via Tandem Catalysis of Zn Single Atoms and In2O3‐x

Abstract

AbstractUrea electrosynthesis from co‐electrolysis of CO2 and NO3− (UECN) offers an innovative route for converting waste CO2/NO3− into valuable urea. Herein, Zn single atoms anchored on oxygen vacancy (OV)‐rich In2O3‐x (Zn1/In2O3‐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/Zn1 sites and OVs in promoting the UECN process via a tandem catalysis mechanism, where Zn1‐OV site activates NO3− to form *NH2 while In‐OV site activates CO2 to form *CO. The formed *CO spontaneously migrates from the In‐OV site to the nearby Zn1‐OV site and then couples with *NH2 to generate *CONH2 which is ultimately converted into urea.