Selective CO₂ electroreduction to C₂₊ products, especially ethanol, is regarded as a potential technology for CO₂ utilization but is still a formidable challenge. Herein, we report the highly dispersive trace Ag decorated copper/copper oxide composite (Cu/Cu₂O-Ag-x) for efficient electrochemical CO₂ reduction to C₂₊ products, mainly containing ethylene and ethanol. Physical measurements confirm that the Ag decoration is an effective strategy to tune the surface electronic structure but without changing the valence and morphology of Cu. The performance evaluation of electrochemical CO₂ reduction in a flow cell demonstrates that the activity and selectivity for ethanol production on Cu/Cu₂O can be promoted by the trace Ag modification. The best catalyst, Cu/Cu₂O with merely 0.6 at.% silver decoration, exhibits a significant enhancement in C₂₊ selectivity (60.9 %) as compared to the Ag-free Cu/Cu₂O catalyst (50.4 %). Originated from the formed Cu-Ag sites and thus enhanced affinity with oxygen-adsorbed intermediates on Cu/Cu₂O-Ag-x catalysts, the ethanol formation is favored with a greatly improved Faradaic efficiency (19.2 %) as well as partial current density (305 mA cm⁻²), which are superior to those of Ag-free counterpart (9.1 %, 105 mA cm⁻²). Moreover, the products selectivity remains stable even electrolysis at 900 mA cm⁻² over 8 h, demonstrating the preeminent electrocatalytic stability.

选择性 CO ₂电还原为 C ₂₊产品，尤其是乙醇，被认为是 CO ₂的潜在利用技术，但仍是一项艰巨的挑战。在此，我们报告了高度分散的痕量 Ag 装饰的铜/氧化铜复合材料 (Cu/Cu ₂ O- Ag - x )，用于高效电化学 CO ₂还原为 C ₂₊产品，主要包含乙烯和乙醇。物理测量证实，Ag 装饰是调整表面电子结构的有效策略，但不会改变 Cu 的价态和形态。电化学CO ₂的性能评价流动池中的还原表明，痕量 Ag 修饰可以提高对 Cu/Cu ₂ O 的乙醇生产的活性和选择性。与不含银的 Cu/Cu ₂ O 催化剂 (50.4%)相比，最好的催化剂 Cu/Cu ₂ O 仅具有 0.6 at.% 的银装饰，其 C ₂₊选择性 (60.9%)显着提高。源于形成的 Cu-Ag 位点，从而增强了与 Cu/Cu ₂ O- Ag - x催化剂上的氧吸附中间体的亲和力，乙醇的形成有利于法拉第效率（19.2%）和部分电流密度的极大提高(305 mA cm ^-2)，优于无银对应物 (9.1 %, 105 mA cm ^-2 )。此外，即使在 900 mA cm ^-2电解8 小时内，产物选择性也保持稳定，证明了卓越的电催化稳定性。