Ultralow Coordination Copper Sites Compartmentalized within Ordered Pores for Highly Efficient Electrosynthesis of n-Propanol from CO2

Coordinatively unsaturated copper (Cu) has been demonstrated to be effective for electrifying CO₂ reduction into C₃ products by adjusting the coupling of C₁-C₂ intermediates. Nevertheless, the intuitive impacts of ultralow coordination Cu sites on C₃ products are scarcely elucidated due to the lack of synthetic recipes for Cu with low coordination numbers and its vulnerability to aggregation under reductive potentials. Herein, computational predictions revealed that Cu sites with higher levels of coordinative unsaturation favored the adsorption of C₁ and C₂ intermediates. Building upon the correlations, we constructed an ultralow coordination Cu catalyst from the in situ reduction of copper oxide nanoparticles (CuO NPs) compartmentalized within an ordered porous matrix, achieving a remarkable Faradaic efficiency (FE) for n-propanol (n-PrOH) from CO₂ electroreduction, reaching up to 27.4% in the H-cell at -0.8 V_RHE and 11.8% at 300 mA cm^-2 in the flow cell. The presence and maintenance of ultralow coordination Cu sites during the rigorous electrolysis process contributed to the outstanding performances, as verified by the combination of in situ spectroscopy techniques, disclosing that the formed ultralow coordination Cu sites featured strong adsorption for *C₁ and *C₂ intermediates that lead to n-PrOH.