biostudies-literatureHe XMinistry of Science and Technology of the People's Republic of China (Chinese Ministry of Science and Technology)National Natural Science Foundation of China (National Science Foundation of China)9923https://www.ebi.ac.uk/biostudies/studies/S-EPMC11568296biostudies-literatureUnknown15(1)The membrane electrode assembly (MEA) is promising for practical applications of the electrocatalytic CO₂ reduction reaction (CO₂RR) to multi-carbon (C₂₊) compounds. Water management is crucial in the MEA electrolyser without catholyte, but few studies have clarified whether the co-feeding water in cathode can enhance C₂₊ formation. Here, we report our discovery of pivotal roles of a suitable nanocomposite electrocatalyst with abundant Cu₂O-Cu⁰ interfaces in accomplishing water-promoting effect on C₂₊ formation, achieving a current density of 1.0 A cm^-2 and a 19% single-pass C₂₊ yield at 80% C₂₊ Faradaic efficiency in MEA. The operando characterizations confirm the co-existence of Nature communicationsRoles of copper(I) in water-promoted CO<sub>2</sub> electrolysis to multi-carbon compounds.PMC11568296221210012022YAF1504603Li XZhu MJiang ZHe XSun FWang YLin LZhang QXie SMei BCheng JfalseRoles of copper(I) in water-promoted CO<sub>2</sub> electrolysis to multi-carbon compounds.The membrane electrode assembly (MEA) is promising for practical applications of the electrocatalytic CO₂ reduction reaction (CO₂RR) to multi-carbon (C₂₊) compounds. Water management is crucial in the MEA electrolyser without catholyte, but few studies have clarified whether the co-feeding water in cathode can enhance C₂₊ formation. Here, we report our discovery of pivotal roles of a suitable nanocomposite electrocatalyst with abundant Cu₂O-Cu⁰ interfaces in accomplishing water-promoting effect on C₂₊ formation, achieving a current density of 1.0 A cm^-2 and a 19% single-pass C₂₊ yield at 80% C₂₊ Faradaic efficiency in MEA. The operando characterizations confirm the co-existence of 2024-01-01T00:00:00Z2024 Nov2025-04-03T23:23:51.876Z2025-04-03T23:23:51.876ZS-EPMC115682963954811010.1038/s41467-024-54282-2