Imidazolium ligand-modified Cu 2 O catalysts for enhancing C 2+ selectivity in CO 2 electroreduction via local *CO enrichment

Abstract

Hydrophobic microenvironment engineering on Cu 2 O via alkyl-imidazolium ionic liquids boosts electrochemical CO 2 reduction (CO 2 RR), achieving 63.3% (alkaline) and 30.7% (acidic) C 2 selectivity. Electrochemical CO 2 reduction (CO 2 RR) to synthesize multicarbon products is a critical route for sustainable CO 2 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 Cu 2 O catalysts, using imidazolium-based ionic liquids with alkyl side chains of varying lengths. The optimized OMIm-Cu 2 O catalyst achieves a C 2+ 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 CO 2 RR.