Sub-2 nm Cu and Co Codoping SnO2 Ultrathin Nanosheet with Mesoporous Structure for Efficient Electrocatalytic Urea Synthesis

The production of urea through C-N coupling via the electrochemical coreduction of CO₂ and NO₃^- represents an environmentally friendly and promising approach. However, the C-N coupling reaction encompasses multiple reactants and complex pathways, necessitating a catalyst that exhibits a high efficiency in both CO₂ and NO₃^- reduction. Herein, the sub-2 nm Cu and Co codoped SnO₂ ultrathin nanosheet (SnO₂CuCo) with mesoporous structure is synthesized for the electrochemical coreduction of CO₂ and NO₃^- for urea synthesis, and the thickness of SnO₂CuCo is only 1.8 nm, and the mesoporous size in the ultrathin nanosheet is 2 nm. The as-synthesized SnO₂CuCo achieved a remarkable urea Faraday efficiency (FE) of 50 ± 1% with a production rate as high as 2701.2 ± 99.1 μmol h^-1 g_cat^-1. Additionally, the SnO₂CuCo catalyst demonstrated exceptional stability after 10 catalytic cycles. Through in situ spectroscopic analysis combined with density functional theory computations, it has been revealed that Cu doping facilitates the reduction of CO₂ to CO and enhances CO adsorption, favoring the creation of the essential *CO intermediate species. Meanwhile, Co doping effectively reduces the activation energy required for the C-N coupling reaction, thereby promoting the catalytic performance, specifically the activity and selectivity, of the SnO₂CuCo catalyst in the process of urea synthesis. This finding provides a whole new catalytic strategy for the electrochemical production of urea.