Boosting Electrochemical Urea Synthesis via Cooperative Electroreduction Through the Parallel Reduction

Abstract

Despite recent achievements in the co-reduction electrosynthesis of urea from nitrogen wastes and CO₂, the selectivity and yield of the products remain fairly average because of the competition of the NITRR, CO₂RR, and HER. Here, a strategy involving FeNC catalysts disperse with oxygen-vacancy-rich CeO₂ (FeNC-Ce) is illustrated, in which the reversible hydrogenation of defects, and bimetallic catalytic centers enable spontaneous switching between the reduction paths of NO₃⁻ and CO₂. The FeNC-Ce electrocatalyst exhibits an extremely high urea yield and Faraday efficiency (FE) of 20969.2 µg mg⁻¹ h⁻¹ and 89.3%, respectively, which is highly superior to most reported values (maximum urea yield of 200–2300 µg mg⁻¹ h⁻¹, FE_max of 11.5%–83.4%). The study findings, rationalize by in situ spectroscopy and theoretical calculations, are rooted in the evolution of dynamic NITRR and CO₂RR co-reduction involving protons, alleviating the overwhelming single-system reduction of reactants and thereby minimizing the formation of by-products.