Stabilizing Cu+ species and enriching reaction intermediates via histidine interface engineering for urea electrocatalysis

Histidine-functionalized Cu 2 O effectively stabilizes Cu + species under cathodic conditions. • The histidine functionalization enhances the co-adsorption of *CO and *NO x intermediates. • The formation of an interfacial hydrogen-bond network on the catalyst surface accelerates proton transfer kinetics. • The histidine-functionalized Cu 2 O catalyst achieves a high urea Faradaic efficiency alongside a notably high yield rate. Electrocatalytic C-N coupling for urea synthesis from CO 2 and nitrate (NO 3 - ) offers a sustainable alternative to the energy-intensive industrial process. Copper (Cu)-based catalysts are uniquely capable of activating both CO 2 and NO 3 - ; however, the catalytically active Cu + species is prone to over-reduction to Cu 0 under cathodic conditions, leading to poor selectivity and instability. Herein, we report a histidine-functionalized Cu 2 O nanospheres (His-Cu 2 O NSs) that stabilize Cu + under operating conditions. The preserved Cu + electronic structure promotes synchronized adsorption of *CO and *NO x intermediates, while protonated amino groups construct a hydrogen-bonded interfacial water network that accelerates proton transfer. As a result, the optimized catalyst achieves a urea Faradaic efficiency of 42.3% and a yield rate of 41.9 mmol h −1 g −1 at −1.1 V potential, with exceptional stability over 100 h in both H-type and flow cells. In situ spectroscopy and density functional theory calculations reveal that histidine coordination not only enhances *CO adsorption but also lowers the energy barrier for C-N coupling, thereby accelerating C-N bond formation. Meanwhile, the in-situ EXAFS results indicate that Cu + species can effectively be retained after histidine modification. This work establishes a molecular-level design principle for regulating complex multi-reactant electrocatalysis and provides a versatile strategy for promoting efficient C-N coupling reactions. Download: Download high-res image (156KB) Download: Download full-size image Functionalizing Cu 2 O nanospheres establishes a generalizable stabilization-via-delocalization principle providing a blueprint for designing durable organic-inorganic interfaces for electrocatalytic urea synthesis.