Hydrophobically modified <scp>Cu₂O</scp> nanocube for selective <scp>CO₂</scp> electroreduction to <scp>C₂</scp>₊ products

Abstract The electrochemical conversion of CO 2 into carbonaceous fuels and chemicals emerges as a promising sustainable strategy toward energy‐rich chemical feedstocks. However, CO 2 reduction reaction (CO 2 RR) in aqueous environments is highly intricate, as protons may be directly reduced to H 2 . Here, we propose a “dual‐functional oleic acid (OA) coordination” strategy that simultaneously stabilizes Cu + /Cu 0 interface via covalent OCu chelating bonds and tailors hydrophobic gas–liquid–solid interfaces. The OA ligands form a bidentate configuration, anchoring Cu + sites while exposing hydrophobic alkyl chains to enrich local CO 2 concentration. As a result, the OA‐Cu 2 O nanocube exhibits an impressive C 2+ Faradaic efficiency (FE) of 74.7% at −0.92 V vs. RHE under a current density of 400 mA cm −2 , along with stable operation for 40 h at 189.8 mA cm −2 in a membrane electrode assembly (MEA). Notably, the competing hydrogen evolution reaction (HER) is effectively suppressed to a low FE of 8.1%. Operando Raman and attenuated total reflection surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) reveals the improved the *CO coverage, blocking the sites for competing *H adsorption. The theoretical study further demonstrates that OA‐induced electron‐deficient regions strengthen *CO adsorption while repelling H 2 O, synergistically promoting CC coupling and inhibiting proton access.