Hollow Copper Nanocubes Promoting CO₂ Electroreduction to Multicarbon Products

Electrochemical carbon dioxide reduction reaction (CO2RR) to multicarbon (C2+) compounds holds great potential for achieving carbon neutrality and storing intermittent renewable energy. The formation of carbon–carbon (C–C) bonds, affected by the concentration of *CO intermediates on the surface of catalysts, is critical to facilitate the production of C2 species. Here, a novel method to prepare uniform hollow oxide-derived copper crystals is reported, reducing CO2 to C2 products (ethylene and ethanol) with an outstanding Faradaic efficiency of 71.1% in 0.1 M KHCO3. The degree of hollowness shows a positive tendency to C2 selectivity but negative to H2 and C1 selectivity. In situ surface-enhanced infrared absorption spectroscopy indicates that hollow structures enhance localized *CO concentration, boosting C–C coupling for producing C2 products. This provides a feasible strategy to enrich important intermediates to deeper reduction products through catalyst structure engineering