Cascade Dual Sites Modulate Local CO Coverage and Hydrogen-Binding Strength to Boost CO₂ Electroreduction to Ethylene

Rationally modulating the binding strength of reaction intermediates on surface sites of copper-based catalysts could facilitate C-C coupling to generate multicarbon products in an electrochemical CO₂ reduction reaction. Herein, theoretical calculations reveal that cascade Ag-Cu dual sites could synergistically increase local CO coverage and lower the kinetic barrier for CO protonation, leading to enhanced asymmetric C-C coupling to generate C₂H₄. As a proof of concept, the Cu₃N-Ag nanocubes (NCs) with Ag located in partial Cu sites and a Cu₃N unit center are successfully synthesized. The Faraday efficiency and partial current density of C₂H₄ over Cu₃N-Ag NCs are 7.8 and 9.0 times those of Cu₃N NCs, respectively. In situ spectroscopies combined with theoretical calculations confirm that Ag sites produce CO and Cu sites promote asymmetric C-C coupling to *COCHO, significantly enhancing the generation of C₂H₄. Our work provides new insights into the cascade catalysis strategy at the atomic scale for boosting CO₂ to multicarbon products.