Electrochemical CO₂ or CO reduction to high-value C₂₊ liquid fuels is desirable, but its practical application is challenged by impurities from cogenerated liquid products and solutes in liquid electrolytes, which necessitates cost- and energy-intensive downstream separation processes. By coupling rational designs in a Cu catalyst and porous solid electrolyte (PSE) reactor, here we demonstrate a direct and continuous generation of pure acetic acid solutions via electrochemical CO reduction. With optimized edge-to-surface ratio, the Cu nanocube catalyst presents an unprecedented acetate performance in neutral pH with other liquid products greatly suppressed, delivering a maximal acetate Faradaic efficiency of 43%, partial current of 200 mA⋅cm⁻², ultrahigh relative purity of up to 98 wt%, and excellent stability of over 150 h continuous operation. Density functional theory simulations reveal the role of stepped sites along the cube edge in promoting the acetate pathway. Additionally, a PSE layer, other than a conventional liquid electrolyte, was designed to separate cathode and anode for efficient ion conductions, while not introducing any impurity ions into generated liquid fuels. Pure acetic acid solutions, with concentrations up to 2 wt% (0.33 M), can be continuously produced by employing the acetate-selective Cu catalyst in our PSE reactor.

电化学CO ₂或CO 还原成高价值C ₂₊液体燃料是可取的，但其实际应用受到来自液体电解质中联产液体产物和溶质的杂质的挑战，这需要成本和能源密集型的下游分离过程。通过将铜催化剂和多孔固体电解质 (PSE) 反应器中的合理设计相结合，我们展示了通过电化学 CO 还原直接和连续生成纯乙酸溶液。凭借优化的边-面比，Cu 纳米立方体催化剂在中性 pH 条件下呈现出前所未有的醋酸盐性能，而其他液体产品则受到极大抑制，最大醋酸法拉第效率为 43%，分流电流为 200 mA·cm ^-2，高达 98 wt% 的超高相对纯度，以及超过 150 小时连续运行的出色稳定性。密度泛函理论模拟揭示了沿着立方体边缘的阶梯位点在促进醋酸盐途径中的作用。此外，除了传统的液体电解质之外，PSE 层被设计用于分离阴极和阳极以实现有效的离子传导，同时不会将任何杂质离子引入生成的液体燃料中。通过在我们的 PSE 反应器中使用乙酸选择性铜催化剂，可以连续生产浓度高达 2 wt% (0.33 M) 的纯乙酸溶液。