Electrochemical carbon monoxide (CO) reduction to high-energy-density fuels provides a potential way for chemical production and intermittent energy storage. As a valuable C₃ species, n-propanol still suffers from a relatively low Faradaic efficiency (FE), sluggish conversion rate and poor stability. Herein, we introduce an “atomic size misfit” strategy to modulate active sites, and report a facile synthesis of a Pb-doped Cu catalyst with numerous atomic Pb-concentrated grain boundaries. Operando spectroscopy studies demonstrate that these Pb-rich Cu-grain boundary sites exhibit stable low coordination and can achieve a stronger CO adsorption for a higher surface CO coverage. Using this Pb-Cu catalyst, we achieve a CO-to-n-propanol FE (FE_propanol) of 47 ± 3% and a half-cell energy conversion efficiency (EE) of 25% in a flow cell. When applied in a membrane electrode assembly (MEA) device, a stable FE_propanol above 30% and the corresponding full-cell EE of over 16% are maintained for over 100 h with the n-propanol partial current above 300 mA (5 cm² electrode). Furthermore, operando X-ray absorption spectroscopy and theoretical studies reveal that the structurally-flexible Pb-Cu surface can adaptively stabilize the key intermediates, which strengthens the *CO binding while maintaining the C–C coupling ability, thus promoting the CO-to-n-propanol conversion.

电化学一氧化碳（CO）还原为高能量密度燃料为化学生产和间歇性能量存储提供了潜在的途径。正丙醇作为一种有价值的C _{3物种，仍然存在法拉第效率(FE)较低、转化率慢和稳定性差的问题。}在此，我们引入了一种“原子尺寸失配”策略来调节活性位点，并报告了一种具有大量原子 Pb 浓集晶界的 Pb 掺杂 Cu 催化剂的简便合成方法。原位光谱研究表明，这些富含 Pb 的 Cu 晶界位点表现出稳定的低配位，并且可以实现更强的 CO 吸附，从而获得更高的表面 CO 覆盖率。使用这种 Pb-Cu 催化剂，我们在流通池中实现了 47 ± 3% 的 CO 转化为正丙醇 FE (FE_丙醇) 和 25% 的半电池能量转换效率 (EE)。当应用于膜电极组件（MEA）装置时，在正丙醇_分流电流高于300 mA（5 cm ²电极）。此外，原位X射线吸收光谱和理论研究表明，结构灵活的Pb-Cu表面可以自适应地稳定关键中间体，从而在保持C-C偶联能力的同时增强*CO结合，从而促进CO到-正丙醇转化率。