Relay Catalysis of Isolated Rhodium-Alloyed Copper Boosts Urea Electrosynthesis from Nitrate and CO₂.

Abstract

Urea electrosynthesis from the coelectrolysis of NO₃^- and CO₂ (UENC) presents a fascinating approach for simultaneously migrating NO₃^- pollutants and producing valuable urea. In this study, isolated Rh-alloyed copper (Rh₁Cu) is explored as a highly active and selective catalyst toward the UENC. Combined in situ spectroscopic analysis and theoretical calculations reveal the relay catalysis of the Rh₁ site and Cu site to promote the UENC energetics, in which the Rh₁ site activates NO₃^- to form *NH₂ while the Cu site activates CO₂ to form *CO. The formed *CO is then migrated from the Cu substrate to the nearby Rh₁ site, which promotes the C-N coupling of *NH₂ and *CO toward the urea formation. Prominently, Rh₁Cu achieves an exceptional UENC performance in the flow cell, exhibiting the highest urea-Faradaic efficiency of 67.10% and urea yield rate of 50.36 mmol h^-1 g^-1 at -0.6 V versus RHE.