Ultrathin 5-fold twinned sub-25 nm silver nanowires enable highly selective electroreduction of CO2 to CO

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.