Electrochemical urea synthesis from CO2 and NO on p-block Bi isolated sites via *CO-mediated C-N coupling

Abstract

Electrochemical urea synthesis from CO2 and NO (EUCN) offers a promising route for sustainable urea production, whereas it still suffers from low C-N coupling efficiency and poor selectivity. Herein, atomically dispersed p-block Bi catalyst is explored for highly active and selective EUCN. Theoretical calculations and in situ spectroscopic analyses reveal a unique *CO-mediated C-N coupling mechanism, where isolated Bi sites facilitate CO2 reduction for *CO formation and enrichment, while *CO-enriched microenvironment boosts subsequent C-N coupling of *CO and *NO to *CONO, a critical C-N intermediate for urea generation, while simultaneously suppressing the competing side reactions. Notably, by pairing cathodic EUCN with anodic glycerol oxidation in a membrane electrode assembly electrolyzer, we achieve a record-high performance with urea yield rate of 86.5 mmol·h–1·g–1 and Faradaic efficiency of 52.1%, as well as the outstanding stability for over 200 h electrolysis.