Microdomain tandem catalysis for efficient CO₂-to-C₂₊ conversion at industrial current densities

Electrocatalytic CO₂ reduction (eCO₂RR) to multi‑carbon (C₂₊) products offers a promising pathway for sustainable energy storage and carbon neutrality. However, the strong reliance on precisely engineered catalyst structures and complex synthesis protocols poses significant challenges for the scalability and practical implementation of eCO₂RR technologies. Herein, we introduced a microdomain tandem catalysis strategy to construct a facile yet efficient Cu₂O/Nafion/Ag catalyst that enhances C₂₊ selectivity. In situ characterizations and theoretical calculations reveal that Nafion-coated Ag nanoclusters serve as active sites for CO₂-to-CO conversion, whereas adjacent grain-boundary-rich Cu₂O domains facilitate CC coupling of locally accumulated CO intermediates. The effectiveness of this microdomain tandem catalysis relies on an optimized structural configuration, as both excessive and insufficient Ag loading can lead to inadequate CO enrichment or hinder CO transport. Consequently, the optimized catalyst achieves over 70 % Faradaic efficiency (FE) for C₂₊ products at industrially relevant current densities (200-250 mA cm^-2) using a 5 cm² membrane electrode assembly (MEA) electrolyzer. This work provides a new strategy for designing low-cost, efficient catalysts and significantly advances the commercialization potential of eCO₂RR.