A high-energy hydrogen radical initiates efficient electrosynthesis of urea from CO₂ and N₂

The electrochemical co-reduction of CO₂ and N₂ to urea presents a sustainable alternative to conventional synthesis but faces substantial challenges. Here we design a catalyst by anchoring the ionic liquid (IL) 1-ethyl-2,3-dimethylimidazolium bromide onto a CuBi surface. The IL@CuBi catalyst delivers an exceptional Faradaic efficiency toward urea (FE_urea) of 73.0% and a current density of 27.4 mA cm^-2 in an H-type cell, with a production rate of 124.7 μmol cm^-2 h^-1. Detailed study indicates that during the co-reduction process, Emmim⁺ cations on IL@CuBi are first reduced to Emmim^· radicals, which transfer electrons to H⁺ to generate H^· radicals. This relayed electron-transfer pathway for H^· radical generation bypasses the conventional formation from surface-adsorbed *H intermediates, thereby effectively suppressing the hydrogen evolution reaction. The generated H^· radicals, acting as high-energy bullets, directly participate in subsequent hydrogenation steps, thereby substantially reducing the free energy barrier and enhancing reaction kinetics.