Pd─O─Cu Bridging Promotes Co-Adsorption of CO and NH₂ Intermediates for Efficient Electrocatalytic Urea Synthesis Over Pd-La_1.6CuO₄

Electrocatalytic urea synthesis from CO₂ and nitrate (NO₃⁻) represents a promising route for carbon mitigation and sustainable chemical production. However, the efficiency of this process remains limited, largely due to the high energy barrier of C─N coupling step, resulting in low Faradaic efficiency (FE) and yield rate. Herein, Pd nanoclusters anchored on La_1.6CuO₄ nanofibers (Pd-La_1.6CuO₄) were constructed to promote the interfacial interaction via Pd─O─Cu bridging for electrocatalytic urea synthesis. Such a configuration facilitates the electron transfer from Cu to Pd and promotes the co-adsorption of C/N-containing intermediates (^*CO and ^*NH₂), thereby boosting the urea synthesis with a high FE of 56.25% and promising yield rate of 241.75 µg·h⁻¹·mg cat⁻¹. Operando electrochemical spectroscopy confirms the formation of key intermediates (^*NH₂ and ^*CONH₂), suggesting that ^*CO couples with ^*NH₂ to form ^*CONH₂, which then converts to CO(NH₂)₂ at the Pd─O─Cu sites. Theoretical calculations reveal that Pd_4d-O_2p-Cu_3d orbital hybridization creates a continuous electronic structure near the Fermi level, which lowers the C─N coupling energy barrier for the rate-determining step from ^*CONH₂ to CO(NH₂)₂. This work presents a strategy based on the co-adsorption of C/N-containing intermediates for highly efficient urea synthesis and advances the research on Cu-based perovskite oxide electrocatalysts.