Electrochemical reduction of CO₂ (CO₂RR) holds the potential to battle the greenhouse effect through the synthesis of carbon-neutral fuels. The high efficiency of noble metal catalysts for CO₂RR is, therefore, highly desirable to reduce the quantities of noble metals. We herein synthesized 5-fold twinned Ag nanowires (NWs) with diameters less than 25 (D-25) and 100 nm (D-100) through a facile bromide-mediated polyol method and subsequently, investigated their structure-driven enhanced catalytic activity for CO₂RR. Compared with D-100 Ag NWs and Ag nanoparticles (NPs), D-25 Ag NWs possess remarkably enhanced current density $(j)$, together with significantly increased Faraday efficiencies (FEs) and energy efficiencies (EEs) over a broad potential range and achieve their maximum values of 99.3% and 61.3%, respectively. More importantly, a quite low onset overpotential (η) to initiate CO₂RR and a stability with negligible degradation of over 24 h were obtained, further verifying the superior performance of D-25 Ag NWs for CO₂RR. Density functional theory (DFT) calculations reveal that the improved catalytic activity over the ultrathin 5-fold twinned Ag NWs originates from the increased ratio of the catalytically active sites contributed by both diameter and length effects, and the special 5-fold twinned nanostructure completely enclosed by energetically favorable facets for CO₂RR.

CO _2的电化学还原（CO ₂ RR）具有通过碳中和燃料的合成来对抗温室效应的潜力。因此，非常需要用于减少CO ₂ RR的贵金属催化剂，以减少贵金属的量。我们在这里通过一种简便的溴化物介导的多元醇方法合成了直径小于25（D-25）和100 nm（D-100）的5倍孪晶Ag纳米线（NWs），随后研究了它们的结构驱动的增强催化活性CO ₂ RR。与D-100 Ag纳米线和Ag纳米粒子（NP）相比，D-25 Ag纳米线具有显着增强的电流密度$（Ĵ）$，以及在很宽的潜力范围内显着提高的法拉第效率（FE）和能源效率（EE），并分别达到99.3％和61.3％的最大值。更重要的是，获得了非常低的启动CO ₂ RR的起始电势（η），以及在24小时内可忽略不计的降解的稳定性，进一步证明了D-25 Ag NW在CO ₂ RR方面的优越性能。密度泛函理论（DFT）计算表明，与超薄5倍孪晶Ag纳米线相比，改进的催化活性源自直径和长度效应共同作用的催化活性位点比例的增加，以及特殊的5倍孪晶纳米结构被完全封闭通过在能源方面有利于CO ₂ RR方面。