Renewable electricity-powered CO₂ reduction to multi-carbon (C₂₊) products offers a promising route to realization of low-carbon-footprint fuels and chemicals. However, a major fraction of input CO₂ (>85%) is consumed by the electrolyte through reactions with hydroxide to form carbonate/bicarbonate in both alkaline and neutral reactors. Acidic conditions offer a solution to overcoming this limitation, but also promote the hydrogen evolution reaction. Here we report a design strategy that suppresses hydrogen evolution reaction activity by maximizing the co-adsorption of CO and CO₂ on Cu-based catalysts to weaken H* binding. Using density functional theory studies, we found Pd–Cu promising for selective C₂₊ production over C₁, with the lowest ∆G_OCCOH* and ∆G_OCCOH* - ∆G_CHO*. We synthesized Pd–Cu catalysts and report a crossover-free system (liquid product crossover <0.05%) with a Faradaic efficiency of 89 ± 4% for CO₂ to C₂₊ at 500 mA cm⁻², simultaneous with single-pass CO₂ utilization of 60 ± 2% to C₂₊.

可再生电力 CO ₂减少为多碳 (C ₂₊ ) 产品为实现低碳燃料和化学品提供了一条有希望的途径。然而，输入 CO ₂ (>85%) 的主要部分通过与氢氧化物反应在碱性和中性反应器中形成碳酸盐/碳酸氢盐而被电解质消耗。酸性条件提供了克服这一限制的解决方案，但也促进了析氢反应。_{在这里，我们报告了一种设计策略，该策略通过最大化 CO 和 CO 2}在 Cu 基催化剂上的共吸附以削弱 H* 结合来抑制析氢反应活性。使用密度泛函理论研究，我们发现 Pd-Cu 有望用于选择性 C ₂₊C ₁上的生产，具有最低的 ∆ G _OCCOH*和 ∆ G _OCCOH* - ∆ G _CHO*。我们合成了 Pd-Cu 催化剂并报告了一种无交叉系统（液体产物交叉 <0.05%），在 500 mA cm ^-2下，CO ₂到 C ₂₊的法拉第效率为 89 ± 4% ，同时与单程 CO _{2对 C 2+}的利用率为 60 ± 2% 。