Imidazolium ligand-modified Cu₂O catalysts for enhancing C₂₊ selectivity in CO₂ electroreduction via local *CO enrichment

Electrochemical CO₂ reduction (CO₂RR) to synthesize multicarbon products is a critical route for sustainable CO₂ utilization, yet achieving high selectivity and current density simultaneously remains challenging. While enhancing *CO coverage on catalysts is pivotal for promoting C–C coupling, the dynamic competition between intermediate enrichment and microenvironment regulation necessitates innovative strategies. Here, we employ surface ligand engineering to construct a tunable hydrophobic microenvironment on Cu₂O catalysts, using imidazolium-based ionic liquids with alkyl side chains of varying lengths. The optimized OMIm-Cu₂O catalyst achieves a C₂₊ selectivity of 63.3% in alkaline media and 30.7% in acidic media. Mechanistic studies reveal that hydrophobic long-chain ligands elevate local *CO concentration, facilitating efficient C–C coupling. This work highlights microenvironment modulation as a viable pathway to bridge the gap between high efficiency and industria–current–density performance in CO₂RR.