Solar-driven CO 2 -to-ethanol conversion enabled by continuous CO 2 transport via a superhydrophobic Cu 2 O nano fence.

The overall photocatalytic CO 2 reduction reaction presents an eco-friendly approach for generating high-value products, specifically ethanol. However, ethanol production still faces efficiency issues (typically formation rates <605 μmol g -1 h -1 ). One significant challenge arises from the difficulty of continuously transporting CO 2 to the catalyst surface, leading to inadequate gas reactant concentration at reactive sites. Here, we develop a mesoporous superhydrophobic Cu 2 O hollow structure (O-CHS) for efficient gas transport. O-CHS is designed to float on an aqueous solution and act as a nano fence, effectively impeding water infiltration into its inner space and enabling CO 2 accumulation within. As CO 2 is consumed at reactive sites, O-CHS serves as a gas transport channel and diffuser, continuously and promptly conveying CO 2 from the gas phase to the reactive sites. This ensures a stable high CO 2 concentration at reactive sites. Consequently, O-CHS achieves the highest recorded ethanol formation rate (996.18 μmol g -1 h -1 ) to the best of our knowledge. This strategy combines surface engineering with geometric modulation, providing a promising pathway for multi-carbon production.