Tuning Structural and Compositional Effects in Pd-Au Nanowires for Highly Selective and Active CO2 Electrochemical Reduction Reaction

CO2 electrochemical reduction is a promising technology to control the concentration of atmospheric CO2 and store renewable energy. However, it is extremely challenging to selectively produce important chemicals such as CO with reasonable low overpotentials and high reaction rates. In this study, twisted Pd-Au nanowires with a unique core-shell and grain boundary-rich structure are developed. Compared with Pd nanoparticles, the synthesized nanowires have a significantly improved CO selectivity. A maximum CO faradaic efficiency (FE) of 94.3% (at -0.6 V), and an extremely low overpotential of 90 mV for CO formation with an FE of 8.5% can be achieved on Pd0.8Au nanowires. The Pd0.8Au nanowires also show superior specific and mass activities especially at low overpotentials. The low overpotential and high selectivity for CO2-to-CO electrocatalytic conversion are achieved simultaneously for the first time on Pd-based nanocatalysts. Combined in situ infrared spectroscopic studies with an attenuated total reflection configuration and density function theory calculations reveal that surface CO could be more facilely generated at much lower overpotentials on nanowires as compared with that on particles. Additionally, the Au atoms in Pd-Au nanowires promote the formation of linearly bonded CO, which is easier to desorb, resulting in a fast reaction rate.